Hey guys, I'm looking at possibly rebuilding the 2.5 Iron Duke in my daughter's Pontiac Fiero. The motor is pretty solid right now, and runs fairly well, at least as much as I can tell. I haven't done a compression test or anything, but if I can get a rebuild kit, I may consider just rebuilding it. Does anyone know if there is a company that sells a "kit" or do I need to source all the parts separately?
Basically looking for a complete bearing kit, and if the sidewall has any perceivable wear, I might have it machined to take an overbore piston, etc. Also, is there a decent cam that provides just a little bit more snappiness that still works totally fine with the existing ECM? I'm not trying to build a race car, I just want something that has a little bit more get up and go. I think stock is 92hp, I don't know what motor my 85 has (whether it has the roller lifters or not), but if it does not, I'll probably try to buy an 86 car and swap that in. Would like to get it to run a little bit more smoothly, and perhaps about ~100-110hp without a loud exhaust or any crazy stuff.
I used to have one of those Holley TBI upgrade units, but for the life of me I cannot find it anymore (must have given it away... they are like gold now for the LU5 V8 guys).
Anyway, just looking for someone who did a mild upgrade when they rebuilt their relatively stock 2.5. Again, not looking to build an SD-4... just want something that looks stock but just feels a little bit smoother and snappier.
Thanks!
EDIT: I guess a lot has changed. I used to be able to find rebuilt Fiero or crate engines at all the major suppliers... can't seem to find a single company that has a crate motor anymore?
[This message has been edited by 82-T/A [At Work] (edited 04-17-2023).]
Is likely doesn't need a rebuild but will need Timing Gears. Duke Fiber Timing Gear Does wears out. Way faster if has problems w/ Distributor and/or oil pump that runs off the cam.
Very Likely You're Not going to find a Roller Cam in OE or aftermarket grind off the shelf. Maybe hard to find a total custom unless paying $$$$$.
No-one stocks motors for most 25-30+ year old cars. Only "Popular" units like maybe Ford 302 V8 used by Millions of cars.
Can Find Rebuild Kits but many don't have the best parts in them like Felpro Valve Cover Gasket Kit w/ Silicone gasket and extra hardware to stop leak there. Or Felpro Intake Casket prevent leak that #4 cylinder sucking coolant.
There was a "Sealed Power" cam and lifter kit for the 2.5L but it was flat tappet. I had one on my 84 but 85+ are supposed to be rollers. I don't know if an aftermarket cam was ever made for the roller engines. I don't know if GM switched engines precisely at the model year boundary - seems to me there could be some overlap, so especially if this is an early 85 then try to figure out what you really have. My timing gear failed at 122K, no idea how common and predictable that is though. That's when the cam got replaced (from the side, engine stayed in the car).
A long time ago there were some long threads on here about upgrades for the 2.5L (once you get past all the "boat anchor"/swapit comments). I don't have the links anymore, but it generally amounted to integrating improvements from later generations of the engine (which extended into the early 90s). The 1987 TBI is supposed to be better, and I think maybe it's possible to use a further improved TBI from ~1990 or whatever. It's all vague to me now, you'd have to find the old threads.
Back when I drove my 84 I always wanted that Holley TBI, but I didn't have the money for it and then it disappeared from Fiero Store. Then right after I gave up on the car, eBay started teasing me with cheap auctions for both the Holley TBI and the Holley intake manifold that's supposed to work with it. If the frame had not been rotted by salt, I always wished I'd been able to rebuild the engine and add those upgrades. I never had that engine at it's best, it was a tired old thing with blowby and a performance cam slapped in without the engine ever getting the overhaul that it needed.
I remember seeing a comment somewhere that claimed an old carburetor intake performed better on the 2.5L than the factory TBI. I have no idea if that's true. In any case for an 85+ roller engine it probably makes more sense to upgrade to later-gen parts instead of old "hotrod" parts that got made for late 70s/early 80s engines.
AMS Racing has kits. looks quite reasonable. sleek
Thanks Sleek, they have some good stuff there, but their kit seems to have parts that are for non-Fiero specific engines... but I can definitely buy some of the parts separately.
quote
Originally posted by theogre:
Is likely doesn't need a rebuild but will need Timing Gears. Duke Fiber Timing Gear Does wears out. Way faster if has problems w/ Distributor and/or oil pump that runs off the cam.
Very Likely You're Not going to find a Roller Cam in OE or aftermarket grind off the shelf. Maybe hard to find a total custom unless paying $$$$$.
No-one stocks motors for most 25-30+ year old cars. Only "Popular" units like maybe Ford 302 V8 used by Millions of cars.
Can Find Rebuild Kits but many don't have the best parts in them like Felpro Valve Cover Gasket Kit w/ Silicone gasket and extra hardware to stop leak there. Or Felpro Intake Casket prevent leak that #4 cylinder sucking coolant.
Thanks Ogre, your page actually states that 1986 2.5s had the rollers. I've had a few Fieros, but the other 1985 that I owned many years ago, also had flat-tappets. Ideally, the roller-cam does make a perceivable difference... so I do hope that that's what I have. I guess my question though is, what exactly, if anything, is different about the non-roller lifter block, and the roller lifter block? I don't think the casing is different, it just means that if I wanted the roller lifters, that I would simply need to replace the pushrods and the cam as well. The lifters should still fit and everything, correct? I suppose that other than the distributor gear on the cam, the cam generally doesn't take any wear... and if I wanted to upgrade that cam (so to speak), I could really just replace the rocker arms with slightly higher ratio ones, right?
If I remember correctly, the plate that allows me to see what type of lifters I have is directly under the intake manifold... like, held in place by 3 bolts or something. So I'll try to figure that out this weekend. Here's hoping...
quote
Originally posted by armos:
There was a "Sealed Power" cam and lifter kit for the 2.5L but it was flat tappet. I had one on my 84 but 85+ are supposed to be rollers. I don't know if an aftermarket cam was ever made for the roller engines. I don't know if GM switched engines precisely at the model year boundary - seems to me there could be some overlap, so especially if this is an early 85 then try to figure out what you really have. My timing gear failed at 122K, no idea how common and predictable that is though. That's when the cam got replaced (from the side, engine stayed in the car).
A long time ago there were some long threads on here about upgrades for the 2.5L (once you get past all the "boat anchor"/swapit comments). I don't have the links anymore, but it generally amounted to integrating improvements from later generations of the engine (which extended into the early 90s). The 1987 TBI is supposed to be better, and I think maybe it's possible to use a further improved TBI from ~1990 or whatever. It's all vague to me now, you'd have to find the old threads.
Back when I drove my 84 I always wanted that Holley TBI, but I didn't have the money for it and then it disappeared from Fiero Store. Then right after I gave up on the car, eBay started teasing me with cheap auctions for both the Holley TBI and the Holley intake manifold that's supposed to work with it. If the frame had not been rotted by salt, I always wished I'd been able to rebuild the engine and add those upgrades. I never had that engine at it's best, it was a tired old thing with blowby and a performance cam slapped in without the engine ever getting the overhaul that it needed.
I remember seeing a comment somewhere that claimed an old carburetor intake performed better on the 2.5L than the factory TBI. I have no idea if that's true. In any case for an 85+ roller engine it probably makes more sense to upgrade to later-gen parts instead of old "hotrod" parts that got made for late 70s/early 80s engines.
Yeah, I remember that TBI unit. I bought one way back in the day. Unfortunately, they were super popular for Corvette and TransAm/Camaro owners that had the LU5 305 V8 with the "Cross-Fire Injection" engine. It uses the exact same TBI unit as the Fiero, except that it uses two of them. So the Corvette / F-body owners were snapping them up. I did get one, but after I sold my 84 Fiero, I ended up just giving it away to someone else. Really wish I still had it because it was a fantastic TBI unit. The stock intake was already made to support a larger TBI unit if I remember correctly, and it came with the larger mounting gasket/plate. But yeah, I remember seeing that intake manifold as well, and never was able to find it.
There are actually quite a few Holley TBI units that have similar bolt patterns and will fit, but finding them is the problem.
I mean, I realize the 2.5 is half a Pontiac 302, but I should be able to get it to the point where it's running somewhat smooth. I like the originality and simplicity of that motor for my daughter's car... so that anything that might go wrong with it, is super-simple to fix. So that's why I'm sticking with it for her car.
Yeah, I'll have to check compression and everything, but I think that's probably the next thing I'm going to do... pull the engine. All the other things are so much easier to do when the engine and transmission are out of the car.
I've been told OE lifters and oil holes in the block are different and can't switch flat to roller or other way around. I'm not sure what else is different because Rollers are a lot Taller and connects to anti-twist parts to keep the roller straight.
84 and 85 you need to check cam/lifter type just because many are rollers because engine swap under warranty recall etc. If "DIY" or 3rd parties did a swap, may use whatever available and switch roller to flat cam that includes 86 car w/ older engine bought used or from "Jasper" type companies.
Some "swaps" are likely Trim Level for them too. Example: All 84 Indy may had roller cam. SE 4cyl may had same but 85 SE may had V6 option so maybe that had flat cam L4. While Base and other Trim Levels had Flat cam setup until most or all 86 and later had rollers.
If engine is still in car... Many say 4cyl and even V6 "sucks" never check the gas pedal and cable actually open the TBI/TB to WOT. Just Have someone "floor" the pedal w/o doing anything special and look at TBI butterfly. Or use ECM scanner and read % throttle etc.
Many GM and other cars have this problem but Fiero is worse because of pedal arm design and Very Long cable. See cave Throttle Cable
I've been told OE lifters and oil holes in the block are different and can't switch flat to roller or other way around. I'm not sure what else is different because Rollers are a lot Taller and connects to anti-twist parts to keep the roller straight.
84 and 85 you need to check cam/lifter type just because many are rollers because engine swap under warranty recall etc. If "DIY" or 3rd parties did a swap, may use whatever available and switch roller to flat cam that includes 86 car w/ older engine bought used or from "Jasper" type companies.
Some "swaps" are likely Trim Level for them too. Example: All 84 Indy may had roller cam. SE 4cyl may had same but 85 SE may had V6 option so maybe that had flat cam L4. While Base and other Trim Levels had Flat cam setup until most or all 86 and later had rollers.
If engine is still in car... Many say 4cyl and even V6 "sucks" never check the gas pedal and cable actually open the TBI/TB to WOT. Just Have someone "floor" the pedal w/o doing anything special and look at TBI butterfly. Or use ECM scanner and read % throttle etc.
Many GM and other cars have this problem but Fiero is worse because of pedal arm design and Very Long cable. See cave Throttle Cable
Thanks Ogre, we're going through the entire car to make sure everything is in top shape. My daughter just finished installing the new fuel pump, stainless pickup assembly, and pressure-washing, sanding, priming, and painting the fuel tank. We replaced all the rubber lines, including the fuel fill connectors, and will replace the hard lines next. But this is kind of what got me to this post. I realized... if I pull the engine, doing all of these things will be infinitely easier with the motor out. We also need to replace the battery tray, and it's easier when you're literally standing in the engine bay.
My daughter showing that the tank is ready to go!
But yeah, that's a really good point. I really do hope I have rollers... that would be a big plus for me. I'll check this weekend.
Originally posted by 82-T/A [At Work]: Yeah, I remember that TBI unit. I bought one way back in the day. Unfortunately, they were super popular for Corvette and TransAm/Camaro owners that had the LU5 305 V8 with the "Cross-Fire Injection" engine. It uses the exact same TBI unit as the Fiero, except that it uses two of them. So the Corvette / F-body owners were snapping them up.
Interesting. I never knew those "crossfire" TBIs were the same as the 2.5L, but it makes sense. I guess that's the real reason the aftermarket version got made.
"crossfire" TBI? Whatever BS marketing... GM 220 series TBI is basically EFI to replace any 2 barrel carb for V8. 84-86 Fiero etc 4cyl has 300 series TBI a 1 barrel carb replacement. Can even use on many carb intakes w/ adapter plates.
While shares same design and manufacturing, almost no parts interchange. Maybe the injector(s) and some small parts depending on exact numbers on the 220 and 300. Neither shares anything w/ 700 Series TBI in 87 & later.
"crossfire" TBI? Whatever BS marketing... GM 220 series TBI is basically EFI to replace any 2 barrel carb for V8. 84-86 Fiero etc 4cyl has 300 series TBI a 1 barrel carb replacement. Can even use on many carb intakes w/ adapter plates.
While shares same design and manufacturing, almost no parts interchange. Maybe the injector(s) and some small parts depending on exact numbers on the 220 and 300.
Hi Ogre, GM's Cross-Fire Injection isn't that 2-bbl TBI unit, it's a special intake with alternately placed ECM-controlled TBI units that are designed to create a "whirlwind" effect in the intake. It's actually a really good design, but of course, throttle body injection will never be as good as port-injection. Here is an aftermarket version of the Cross-Fire Injection intake plenum:
It's basically the same as stock, but the aftermarket one is a bit more polished with a bowl opening for the runners. The factory one was less fancy, but basically the same (dirty):
The throttle bodies mount to the two holes on the top of the plenum lid like so:
As you can see, the TBI units are identical to the ones on the 84-86 Fiero (same exact part numbers):
Fully assembled, the CFI looks like this (Corvette):
And on the Camaro/TransAm:
The hole on the top would mate with a rubber isolator on the hood that connected it to fresh-air ducts either at the Cowl (TransAm) or in a center-vent configuration (Camaro).
The Holley TBI units were extremely popular among the CFI crowd because it was a simple plug and play. It required no modification, and the bore opening on the intake mated perfectly with the Holley TBI replacement bore. Kind of unfortunate... because it meant everyone was buying the Holley TBI units for the CFI motors... but I suspect that had the CFI engines not also had these, perhaps Holley never would have bothered making them just for the Fiero (or other Duke cars) anyway.
But yeah, we're not talking about the 2-bbl TBI units that were found in the TBI GM Chevy trucks.
Ok, I never seen that. What a nightmare to have 2 300 series... Only seen 220 Series on some GM "low grade" V8 and a few wanted EFI w/o a lot of work.
It doesn't get a lot of love, most people don't even know about it because it was only really used for... I think like ~4 years? It was first used in the 1981 Corvette, and was last used in the 1984 Corvette (with the newer body style). For the F-body, I think it was only used from 1982-1983... not sure it even made it in the 84 model year.
It really is a pretty cool system, but it was still super-smogged out, so in order to get any real power from it, you needed to hog out the intake ports. GM was forced to intentionally block the ports by almost 30%. They designed them though in a way that any weekend warrior could open them up for full potential. Like... literally, they built up a metal "ramp" at the opening of the port to close it off. So if you just ground 1/4" to 1/2" into the area that was stained by EGR in the intake, it would open it up to the full amount and instant ~20hp.
They offered a 350 version in the Corvette, and a 305 version in the F-body as the LU5.
I think it put out 165hp, and 245lbs of torque in the 305 variety.
With a good cam, no smog stuff, Holley units, you could easily get 250hp with a 305 from it. It really, really woke up on the highway, that's where it was more successful... poor off-the-line power though.
EDIT: Only reason I knew about it is because I had an 82 TransAm... haha...
EDIT 2: Yeah, check this out... I find a picture of one that was hogged out (and cleaned) aftermarket one and an original one with the "ramp" in the intake ports to the cyl head. They block about 2/3rds of it... GM had to do this with the casting last minute in order to make it pass emissions. You remove this, and it immediately gains like 20hp and better fuel economy. Totally ridiculous, but it was the time...
[This message has been edited by 82-T/A [At Work] (edited 04-19-2023).]
Can anyone tell me, is the cyl head from the 1987 different from the 1984-1986 models? Specifically... are the exhaust manifolds different? Or... even more specifically, can I easily use an exhaust manifold from a 1987 in a 1985 Fiero?
87 & up is another motor and Most parts won't work w/ 86 & down.
E-manifold is 1 of very few does work "across the wall" in cave page but OE 87 ones don't have heat stove for Thermac because 700 TBI doesn't need hot air.
Mr Ogre sorry I sound so negative to you .I must sound like an ass but I just post to help owners with less experience. I know you have been around since 99 doing the same thing and I have found out you have been having some health issues. I hope you are doing better .I have tried numerous times to sign into the Ogre's cave but the page seems unavailable Anyway sorry 82-T/A I didn't mean to cut into your thread.
87 & up is another motor and Most parts won't work w/ 86 & down.
E-manifold is 1 of very few does work "across the wall" in cave page but OE 87 ones don't have heat stove for Thermac because 700 TBI doesn't need hot air.
Thanks Ogre, that's exactly what I was looking for. The new aftermarket exhuast manifolds that they're selling for the 1987 model, actually have a newer heat shielding on it, which I think will work better. Because it shares the same motor with like the Grand Am and Oldsmobile (whatever it was at the time), I figure they're just making them all look sort of the same. I want to re-use the Thermac (is that a word or an acronym?) on the newer style manifolds, and get rid of the older style one that goes over the cross-over pipe above the catalytic converter.
This car also has the older-style catalytic converter too... which is enormous, so I'm going to replace it with the newer honeycomb style to get rid of the old charcoal style. The piping is decent, but the cat is looking a little ragged, and I'm sure I can pick up a little horsepower and driveability by going with the newer-style cat.
quote
Originally posted by sleek fiero:
Mr Ogre sorry I sound so negative to you .I must sound like an ass but I just post to help owners with less experience. I know you have been around since 99 doing the same thing and I have found out you have been having some health issues. I hope you are doing better .I have tried numerous times to sign into the Ogre's cave but the page seems unavailable Anyway sorry 82-T/A I didn't mean to cut into your thread.
No problem, I appreciate all the help you've given me, as well as Ogre.
Ogre, do you need help with the website? I'm happy to host it for you for free. How large is it?
[This message has been edited by 82-T/A [At Work] (edited 04-21-2023).]
Thermac is used to prevent Carburetor Icing. Not sure name came from, maybe just a name for TM to register w/ USPTO many decades ago. Name is now "Generic" for all hot air setups. 300 series TBI can see Icing problem too. "Fiero" V6 just route heater loop of cooling system thru TB for same thing.
"Carb" Icing does not need freezing air. Just a "Right" mix of air temp & moisture in that and air flowing thru the Carb/TB/TBI can have ice buildup and engine does weird things to can't run until ice melts.
Some remove or parts fail for whatever anti-icing used and just got lucky never had problems. Is not a good idea to have engine w/o this because can drive for months, ever years, because most icing happens at Random and without Warning. Say you live in hot dry place so "dead" Thermac likely won't mater there but drive to somewhere else and car now stalls or other problems because now TBI is iced. Good luck actually see the problem because can melt and dry out before can stop somewhere and open the hood.
Side Note: Icing may not be in the Carb etc. Ice Maybe before or after them. Just where air flow change going around/thru different parts can mater. Example: Icing maybe happen in "Fiero" V6 weird shape upper intake with the "neck down" section that some modify in other threads. Close to TB and heat pipe to prevent problems even there.
I've seen Carb Icing only on a few vehicles. 1 was first gen Chrysler mini van. Tube between Air Cleaner and Stove fell off and then random stall in slow heavy traffic. Since tube was gone, temp disconnect factory cold air pipe from air cleaner so get some engine bay warm air and stopped stalling. Then got replacement tube. These Tubes need to be rated for high heat. Otherwise When Thermac shuts off, the tube can burn melt or worse.
This car also has the older-style catalytic converter too... which is enormous, so I'm going to replace it with the newer honeycomb style to get rid of the old charcoal style. The piping is decent, but the cat is looking a little ragged, and I'm sure I can pick up a little horsepower and driveability by going with the newer-style cat.
OE cat is Not charcoal. Just different version of new cat for most outside of CA and likely still working. You will not get more power or "driveability" w/ new cat.
Thermac is used to prevent Carburetor Icing. Not sure name came from, maybe just a name for TM to register w/ USPTO many decades ago. Name is now "Generic" for all hot air setups. 300 series TBI can see Icing problem too. "Fiero" V6 just route heater loop of cooling system thru TB for same thing.
"Carb" Icing does not need freezing air. Just a "Right" mix of air temp & moisture in that and air flowing thru the Carb/TB/TBI can have ice buildup and engine does weird things to can't run until ice melts.
Some remove or parts fail for whatever anti-icing used and just got lucky never had problems. Is not a good idea to have engine w/o this because can drive for months, ever years, because most icing happens at Random and without Warning. Say you live in hot dry place so "dead" Thermac likely won't mater there but drive to somewhere else and car now stalls or other problems because now TBI is iced. Good luck actually see the problem because can melt and dry out before can stop somewhere and open the hood.
Side Note: Icing may not be in the Carb etc. Ice Maybe before or after them. Just where air flow change going around/thru different parts can mater. Example: Icing maybe happen in "Fiero" V6 weird shape upper intake with the "neck down" section that some modify in other threads. Close to TB and heat pipe to prevent problems even there.
I've seen Carb Icing only on a few vehicles. 1 was first gen Chrysler mini van. Tube between Air Cleaner and Stove fell off and then random stall in slow heavy traffic. Since tube was gone, temp disconnect factory cold air pipe from air cleaner so get some engine bay warm air and stopped stalling. Then got replacement tube. These Tubes need to be rated for high heat. Otherwise When Thermac shuts off, the tube can burn melt or worse.
Wanted to make sure you knew that my intent was to fix the THERMAC and make use of the newer (better) thermac shielding on the replacement exhaust manifold, rather than try to make use of the older (deteriorated) thermac tins that are on the piping just before the catalytic converter. I don't really think it'll ever be a problem in Florida, but for me... the goal is for the car to warm up faster, so I intend to find new flexible tubing and hook it back up to the air cleaner and the new thermac shielding on the replacement manifold. Right now the vent piping is missing.
I think I know the answer to this... but would I have any issues if I took a 1990 Pontiac GrandAm 151 L4 and put it in my Fiero? Would everything from my daughter's 85 bolt up? Really want a roller block, and just looking at possible options (I may not even need it, but I'll know this weekend). If I remember, the oil pump and some other things were different, right? (88+?)
New E-man comes w/ stove for thermac. Just use that.
Some 4cyl have stoves on E-pipe farther down often does 2 jobs... Stove and heat shield. Heat shield can protect the starter and solenoid. If you lose that for any reason then starter can cook.
later 4cyl heads won't work on 86 & older. That assume all are VIN R version. Other Duke cars use VIN U and can't use whole or parts of that. 87+ heads are made different on intake side only take intake man that's made for 700 TBI.
New E-man comes w/ stove for thermac. Just use that.
Some 4cyl have stoves on E-pipe farther down often does 2 jobs... Stove and heat shield. Heat shield can protect the starter and solenoid. If you lose that for any reason then starter can cook.
later 4cyl heads won't work on 86 & older. That assume all are VIN R version. Other Duke cars use VIN U and can't use whole or parts of that. 87+ heads are made different on intake side only take intake man that's made for 700 TBI.
Thanks Ogre, appreciate it. Sounds like that motor I'm looking at is not an option for me.
Hey guys, I'm looking at possibly rebuilding the 2.5 Iron Duke in my daughter's Pontiac Fiero. The motor is pretty solid right now, and runs fairly well, at least as much as I can tell. I
After many years of experience in industry and hobby, "if it ain't broke don't fix it"
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
After many years of experience in industry and hobby, "if it ain't broke don't fix it"
Yeah, I agree, but in this case it's a learning experience for my daughter (she's rebuilding her first car)
So honestly... I think regardless of what I get, I plan to rebuild the engine with her. But if I'm going to pay the machine shop fees, I'd want to do it with a roller block.
Hey guys... I'm resurrecting this thread because I'm quickly getting to the point where this will become something I want to address sooner.
So, my daughter ran a compression test on the engine last weekend, and essentially, from drivers side to passenger side, the compression was as such:
160 / 60 / 110 / 90
Cyl 1 (whatever it actually is... #4 I think?) had FANTASTIC compression. Second cyl was just attrocious, third was barely adequate, and the last one was also quite bad.
So it's clear that I will need to rebuild it.
I've started collecting parts, and I just bought a Felpro head gasket set... basically, everything from head-gasket up. So that's great.
But now I'm needing to figure out how / what I want to do rebuilding the engine. Truth is, I've never rebuilt an engine before. I assumed everything was a standard size (or maybe), so I could just order basic replacement parts, but I'm realizing that's not the case.
At the end of the day, I recognize that the Iron Duke is very much NOT a performance motor (this one at least isn't), and the operating range probably doesn't even exceed 5,500 rpms... probably doesn't even produce much additional power above 4,800. All of this is to say that I don't need a super specialized machine shop to rebuild this engine ... so, I want my daughter and I to do this together. I've always told myself that if someone else can do it, then I can do it too. I won't go through the list of all the things I can do, but suffice it to say, this isn't above my ability or intelligence. I've just never done it before.
I'd want to do a BASIC rebuild... but looking for some advice on not only what tools I need, but in what order I need to do these things. I assume I need a micrometer, a feeler gauge, and that thing that attaches to my power drill with the stones so I can hone the cyls. I know that I'm also supposed to be using an oil for when I do that... what kind of oil do I use? Also... how do I know what bearings I use? Do I measure the old ones and just order whatever matches up? How do I prep the crank to go back into the block? Do I use some kind of sand paper or leather strap to "polish" the journals? What about the pin that allows me to connect the connecting rod into the piston? What kind of piston does the Duke have... is it one of those ones that go in super easy and it uses a circlip to keep it in, or is it one of those ones that I have to press in. And if it's one of the ones that I press in... how do I make it so the pin goes into the connecting rod and the piston properly... as in, equally spaced? No bearings on that pin, so no idea what I do there.
Is there a step-by-step book (my service manual?) or are there good videos? I have no clue...
Bonus (for me) question... I seem to really have a hard time with cyl heads and torque wrenches. I had a "clicking" torque wrench, that didn't do **** . Both times I used it, it never clicked, and I busted the threads on two engines when I was re-installing a cyl head. In one case, I had to ask a shop to helicoil my motor and re-install the heads for me, and in another... I just said F-it and tightened the other bolts (another Iron Duke I had) and drove it like that (with no leaks.... haha). But I'm not 19 anymore, and want to do it right. What the hell was I doing wrong? Why did it not click? I stopped using one of those and now only use the needle ones, which suck. Any advice?
So, my daughter ran a compression test on the engine last weekend, and essentially, from drivers side to passenger side, the compression was as such:
160 / 60 / 110 / 90
Cyl 1 (whatever it actually is... #4 I think?) had FANTASTIC compression. Second cyl was just attrocious, third was barely adequate, and the last one was also quite bad.
So it's clear that I will need to rebuild it.
It's clear to me that the valves need attention. Unless the engine is burning oil (worn rings), or the rods are knocking (worn bearings), I wouldn't bother rebuilding it.
Having said that, if you pull the head and discover (using a cylinder bore gauge) that the cylinders are badly worn, then you might consider the effort and expense of a total engine rebuild.
Cyl 1 (whatever it actually is... #4 I think?) had FANTASTIC compression. Second cyl was just attrocious, third was barely adequate, and the last one was also quite bad.
So it's clear that I will need to rebuild it.
#1 is Battery end. #4 next to trans.
Is likely test is wrong for many reason because likely won't start, burning a lot oil, and other problems to get those very low numbers.
Let's assume you did the test right and is a Dry test.... Still May not = to rebuild.
More so if car has been parked for months or years.
Rings and Valves get "stuck" in crap and can leak until have run @ highway speeds for an hour or more. More so if fools don't change the oil.
1. Get a bore scope and look into the spark plug hole w/ piston at bottom. Look for damage cyl walls. If true, you need a machine shop or get another engine. look in 1 4 then 2 3. If #4 piston is clean(er) then likely bad intake gasket sucking coolant. 2. If parked, Run the engine then wait to cool/cold and test again. Valve Lifters and more need to run to get oil flowing and if not screw up the meter reading. 3. Then Do a Wet pressure test. Wet test helps tell you if the rings are bad/stuck even if cyl walls look good. 4. try a leak down test too. loaner/rental tools may have that tool.
I don't think you can know in advance the exhaustive list of what will be needed for a given rebuild.
At a minimum, everything is taken apart for cleaning/inspection.
Then, depending on your observations/measurements, you can decide what needs replacing/machining. We can't say at this time what preparation the crankshaft (or other parts) needs.
If you're lucky, and almost nothing needs changing, then you have gained peace of mind by having evaluated the state of everything.
More importantly, the value in a complete teardown is that your daughter can handle a crankshaft and other key components; I wouldn't do just a top-end rebuild in this case.
It's clear to me that the valves need attention. Unless the engine is burning oil (worn rings), or the rods are knocking (worn bearings), I wouldn't bother rebuilding it.
Having said that, if you pull the head and discover (using a cylinder bore gauge) that the cylinders are badly worn, then you might consider the effort and expense of a total engine rebuild.
Thanks Patrick, that was kind of my thought as well... that the issue is with the valves. You've probably seen the video that I've posted before, the car runs and drives just fine, so the engine does run. There's no smoke coming out at any point... though I've not bothered to floor it. I actually have a valve that I took from a top-end rebuild I did many years ago on an 84 Fiero that I had... it had... don't really know how to explain it, not a crack, but a fissure that developed along the side of one of the exhaust valves where I can only assume it was losing compression. I kept it after I rebuilt the engine (and it sits on my desk) just because I thought to myself at the time how crazy it is that the engine ran like this.
If this was a car that I owned for myself and was just going to putz around in, I'd probably just have the cyl head rebuilt. But for me, I want it to be a learning experience for my daughter, so I intend to rebuild it regardless so she'll have that experience. But like you said... my opinion is that it's the valves, and not the block itself. But I will buy a cyl bore gauge.
quote
Originally posted by theogre:
Is likely test is wrong for many reason because likely won't start, burning a lot oil, and other problems to get those very low numbers.
Let's assume you did the test right and is a Dry test.... Still May not = to rebuild.
More so if car has been parked for months or years.
Rings and Valves get "stuck" in crap and can leak until have run @ highway speeds for an hour or more. More so if fools don't change the oil.
1. Get a bore scope and look into the spark plug hole w/ piston at bottom. Look for damage cyl walls. If true, you need a machine shop or get another engine. look in 1 4 then 2 3. If #4 piston is clean(er) then likely bad intake gasket sucking coolant. 2. If parked, Run the engine then wait to cool/cold and test again. Valve Lifters and more need to run to get oil flowing and if not screw up the meter reading. 3. Then Do a Wet pressure test. Wet test helps tell you if the rings are bad/stuck even if cyl walls look good. 4. try a leak down test too. loaner/rental tools may have that tool.
Thanks Ogre, the test was done with the car sitting (having not started) for 2 weeks. Before that though, the car ran and drove fine. This is the video I posted earlier that shows me driving it around the block: https://www.youtube.com/watch?v=1lrNs5OyhXA
It had been warmed up for about 5 minutes before this, and drove maybe less than a mile. Before we bought it, it had been driven regularly and the owner never mentioned any issues. When I pulled the spark plugs, they looked to be fairly new (as though they had been changed within the past year), and weren't dirty or covered in soot either. They all looked the same.
I used a normal compression testing gauge that screws into the spark plug hole. The car had been sitting for two weeks, and with a charged battery, we cranked it about 6 times for each spark plug. Cyl 4 was the best. I have a bore scope (or really, something like it that will fit in there from Harbor Freight), maybe I'll do that and see if I can tell what condition the combustion chambers are in. I plan to pull the engine in the next weekend or two.
quote
Originally posted by pmbrunelle:
I don't think you can know in advance the exhaustive list of what will be needed for a given rebuild.
At a minimum, everything is taken apart for cleaning/inspection.
Then, depending on your observations/measurements, you can decide what needs replacing/machining. We can't say at this time what preparation the crankshaft (or other parts) needs.
If you're lucky, and almost nothing needs changing, then you have gained peace of mind by having evaluated the state of everything.
More importantly, the value in a complete teardown is that your daughter can handle a crankshaft and other key components; I wouldn't do just a top-end rebuild in this case.
Yeah, that's the biggest thing for me... my daughter gaining this experience, otherwise I'd just put something else in there.
Hey guys... I'm resurrecting this thread because I'm quickly getting to the point where this will become something I want to address sooner.
So, my daughter ran a compression test on the engine last weekend, and essentially, from drivers side to passenger side, the compression was as such:
160 / 60 / 110 / 90
Cyl 1 (whatever it actually is... #4 I think?) had FANTASTIC compression. Second cyl was just attrocious, third was barely adequate, and the last one was also quite bad.
Just a bit of anecdotal info. Although my Duke seemed to run fine, with no smoke, I ran a compression test on it, since it was a complete "unknown" to me. (Other than that it had leaked like a sieve when I first got it. Leaked so badly, I called it the "Fiero Valdez".) A few gaskets and a new timing cover took care of most of that. (The rear main seal still leaks a bit, but it's getting swapped anyway, so no worries.)
The compression test showed 145-150, cold, on all cylinders. Odd thing is, it still doesn't have enough compression to hold it on more than a moderate hill. The parking brake is a necessity. 155K on the odo.
Edit - When you ran the compression test, did you do it with the throttle propped wide open? Also, did you let it hit the same number of strokes on each cylinder? I usually let it hit 3-4 strokes, or until it stops climbing. I figure you're probably way ahead of me, but it's worth mentioning.
[This message has been edited by Raydar (edited 05-25-2023).]
Just a bit of anecdotal info. Although my Duke seemed to run fine, with no smoke, I ran a compression test on it, since it was a complete "unknown" to me. (Other than that it had leaked like a sieve when I first got it. Leaked so badly, I called it the "Fiero Valdez".) A few gaskets and a new timing cover took care of most of that. (The rear main seal still leaks a bit, but it's getting swapped anyway, so no worries.)
The compression test showed 145-150, cold, on all cylinders. Odd thing is, it still doesn't have enough compression to hold it on more than a moderate hill. The parking brake is a necessity. 155K on the odo.
Edit - When you ran the compression test, did you do it with the throttle propped wide open? Also, did you let it hit the same number of strokes on each cylinder? I usually let it hit 3-4 strokes, or until it stops climbing. I figure you're probably way ahead of me, but it's worth mentioning.
"...did you do it with the throttle propped wide open?"
No... throttle was completely closed, but the first one I checked hat a PSI of 160 cold.
"Also, did you let it hit the same number of strokes on each cylinder?"
This I did... for the ones that were low, I actually let it go longer.
Is likely doesn't need a rebuild but will need Timing Gears. Duke Fiber Timing Gear Does wears out. Way faster if has problems w/ Distributor and/or oil pump that runs off the cam.
Very Likely You're Not going to find a Roller Cam in OE or aftermarket grind off the shelf. Maybe hard to find a total custom unless paying $$$$$.
No-one stocks motors for most 25-30+ year old cars. Only "Popular" units like maybe Ford 302 V8 used by Millions of cars.
Can Find Rebuild Kits but many don't have the best parts in them like Felpro Valve Cover Gasket Kit w/ Silicone gasket and extra hardware to stop leak there. Or Felpro Intake Casket prevent leak that #4 cylinder sucking coolant.
Wanted to mention it, because it just came in the mail. You suggested that I get the Felpro gasket set (basically, the head gasket set that comes with all the other stuff included). Well, I forgot to mention it, but these were the kits that I used to get whenever I'd do any work on my cars... and I don't know if Felpro isn't making them anymore, or just this specifically... but I bought the very last Felrpo Iron Duke (85-86) head gasket set they had for the Fiero. It was on Close-Out, and was actually a little bit cheaper than one of the other ones, but I specifically got it because I know it's better quality. It's shocking to me how all these things, all these parts that I used to take for granted, are no longer offered.
I keep e-mailing Matt at the Fiero Store if he has "x" product that I know they used to sell. He's been totally nice about it, but I'm sure he's probably getting a little annoyed at having to say, "sorry, we don't offer that anymore." It really makes me realize that if there are parts I need / want, I better get them now.
Originally posted by 82-T/A [At Work]: I keep e-mailing Matt at the Fiero Store if he has "x" product that I know they used to sell. He's been totally nice about it, but I'm sure he's probably getting a little annoyed at having to say, "sorry, we don't offer that anymore." It really makes me realize that if there are parts I need / want, I better get them now.
Does Fiero Store sell things that are not listed on the website?
Are there items for which it is better to ask directly than to check the website?
Does Fiero Store sell things that are not listed on the website?
Are there items for which it is better to ask directly than to check the website?
Matt does have some things that are not on his website, but it's usually very random things... like, something that might have been returned, or there isn't a matching pair. For example, I asked him if he had a set of the cross-drilled rotors for the front of the car. I always saw a lot of brake fade on my old Fiero, and while I don't expect my daughter to have that problem, literally changing out the rotors to cross-drilled totally solved my brake fade issues. He only had one... left side. :/ So unfortunately, not helpful, but he does have a few things, generally though, 90% of the time it's a big no... haha...
YAY... we got down a little ways, and my daughter removed the lifter galley plate... and what do we see... roller lifters!!!
So, pretty excited about that. I really think the roller lifters makes a huge difference in the longevity of the cam, ease with setting valve lash, and to some degree... quieting down the engine. So pretty happy to see this.
Also, as we were going through it, we saw this...
Now... I've had a couple of 4 cyl Fieros. I had an 84 2m4 SE, and an 85 2m4 back in the day... for the life of me, I cannot remember the tach filter being grounded / installed by means of sandwiching the bracket between the transmission and the engine block... madness... haha...
Also... the engine was totally filthy... I mean, almost unlike anything I've ever seen. Only once or twice in my days have I seen an engine so coated in engine oil all over the place, that it looked like this. Totally unbelievable.
When I dumped the coolant by the way, it felt relatively empty. I have to question now at this point if maybe there's a blown head gasket. Oil is not milky, so ideally it's a blown headgasket and not a cracked head. But I'll know more when we remove the cyl head.
82-T/A yes pretty dirty. I don't know if you got my pm but I would strip and basic clean .Take to machine shop for measuring .they know if crank and rods are good and will tell you if its still in spec. Plus you don't have the equipment to properly grind valves and seats or change out guides. You and your daughter should concentrate on the reassembly. sleek
Originally posted by 82-T/A [At Work]: So, pretty excited about that. I really think the roller lifters makes a huge difference in the longevity of the cam, ease with setting valve lash, and to some degree... quieting down the engine. So pretty happy to see this.
Helps w/ longevity and power because rollers allow better cam profile. Does Not do those others because Duke Valves are Not Adjustable.
Even New Lifters does Not reduce valve noise much.
82-T/A yes pretty dirty. I don't know if you got my pm but I would strip and basic clean .Take to machine shop for measuring .they know if crank and rods are good and will tell you if its still in spec. Plus you don't have the equipment to properly grind valves and seats or change out guides. You and your daughter should concentrate on the reassembly. sleek
Hey Sleek, thanks! Yeah, I agree... we dug some more into the engine yesterday (removed the intake, and all the stuff on that side of the engine. Because there was almost no coolant in it, and because I remember seeing some steam from the exhaust... my thought is that there's a head gasket leak, among other things. The bottom-end looks solid, but I honestly won't know until I get the head off.
What I will probably do is pressure-wash the **** out of the engine once it's out. I may not send the block in to the machine shop. The engine was pretty solid, and I don't want them to remove the cam bearings or anything else. I'm confident enough that the bottom-end is solid that I'm just going to rebuild that portion with my daughter, and clean it at home. Hopefully, the wear on the cyl walls isn't that significant, but I'll know once I get the head off, and it may change depending on.
For the cyl head, I'm definitely going to have to send the cyl head out. I'll probably still disassemble and lap the valves with my daughter, just so she has that experience. But I'm going to get it magnafluxed and checked. I'm expecting to see a blown head gasket and badly worn valves.
quote
Originally posted by theogre:
Helps w/ longevity and power because rollers allow better cam profile. Does Not do those others because Duke Valves are Not Adjustable.
Even New Lifters does Not reduce valve noise much.
I would simply say that my experience with the roller lifters (from this engine), compared to the other two dukes I've had... the engine "sound" from the exhaust seems to basically be the same, but I don't hear any "clatter," which is nice. With the other 85 I had (that had flat-tappets), and the 84 that I used to have... both had much more clatter... sounded like an old Ford tractor. The difference is subtle... but the roller-cam engine just sounds smoother, both inside and outside.
What I'm interested in finding though, is if there's a slightly hotter cam available? I haven't seen one anywhere?
Any thoughts on timing gears? I'm going to order new timing gears, so curious what you guys think.
[This message has been edited by 82-T/A [At Work] (edited 05-30-2023).]
