So my trusty 86' 2.5/Auto car has been producing copper flakes in the oil, and oil pressure is starting to read low at cruise. It's not knocking yet, and it handles the 90 mile round trip to work every day still, but I've begun work on setting up an interim replacement engine for it so I'll be ready when it finally decides to blow up. Steven and I scored a healthy looking 2.5L from a 1990 Olds Cutlass Ciera (which will require conversion to an 88' type setup with the wiring and everything, I know), and I found some interesting things about it. For starters, it looks just like a 87-88' Fiero engine on the outside. However, on further inspection, the head has "D" shaped exhaust ports, and the intake manifold has a divorced water passage (to keep the air/fuel in the adjacent runner cooler) - exactly the same as detailed in this thread: https://www.fiero.nl/forum/Forum2/HTML/074087.html. Another interesting thing to note is that the wiring harness appears to have the same passthrough as the Fiero, as well as a C500 and even a C203 - I haven't checked yet to see if the pinouts are the same, but they may very well be. It may even work with minimal to no modification! Something to keep in mind for late model Fiero owners looking for engines or wiring harness parts. The 1990' Olds Cutlass Ciera is listed at ~110Hp and 135 ft/lbs, so it'll be a little bit better than the 92Hp of my current engine, and likely turn a bit more fuel economy which is what I'm after.
So while I'm doing all that, I've been thinking about the Mercruiser 181 (3.0L) crankshaft again. I'm pretty sure that everybody can agree that for the work required, a stroker duke is quite a poor choice in terms of cost to benefit. You're not going to build a 250Hp engine from an old S-10 block, and a boat crank within reason. But what about as an excercise in problem solving? A challenge? Since there's little proven information on topic, I'll take it upon myself to prove or disprove the feasibility of installing a 181 crankshaft into a production 2.5 block within reason. I'll be using as many stock GM components possible - no high dollar, custom parts unless reasonably priced, or absolutely necessary. Since I'm certainly not going to be building anything Super Duty, I call this project SUPER DOOKIE 4... Cuz if I make it happen, It'll still be a pile of... well, you know.
The stock 2.5 crank is on the bottom - the design has been whittled away to the minimum amount of material needed to do the job, and nothing more. Stock 2.5 stroke is 3.0". The late Mercruiser 3.0 crank (also used in industrial engines) is on top, it's fully counterweighted and weighs much more than the 2.5 crank as we know it. The stroke of the 3.0 crank is 3.6". The flywheel bolt hole end of the 3.0 crank will need to be machined down both in diameter, and how much it sticks out to match the 2.5, and then have the 2.5 flywheel bolt hole pattern drilled and tapped. Not that big of a deal for a machine shop to do. I don't know if there's enough metal on the old/2-piece style Mercruiser crank to machine it to the right form.
2.5L: Stroke: 3.0" Rod length: 6.0"
3.0L: Stroke 3.6" Rod length: 5.7" (width: 1.029 - note that it's the same rod as a Chevy inline 6)
So with different strokes and rod lengths between 2.5 and 3.0, where does it put the piston in relation to the deck surface? Can you put the whole Mercruiser rotating assembly into a stock duke block (not taking clearance into account)? Taking what we know and doing the math:
So it looks like both cranks and their respective rods bring the piston up to the same, exact height. With the stock piston CH of 1.56 as listed on the Rockauto web catalog, you end up with an overall compression height of 9.06". The deck height is listed at 9.150", so the stock pistons as they come in the 2.5 are supposedly .090" in the hole? Ouch. Keith Black lists a flat top piston with a 1.6" CH for the 77-78' dukes, which would bump up compression quite a bit. The marine pistons are supposedly at 1.625" and can be had in D dish or flat top. All of them are available in stock bore and overbore, and have a .927" piston pin bore. So from what it looks like, whatever piston that works in the stock duke will also work with the 3.0 crankshaft and rods, provided there's enough clearance for the rods to swing. Sweet.
[This message has been edited by Blue Shift (edited 07-26-2008).]
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01:48 AM
patch Member
Posts: 210 From: Santaquin,UT, USA Registered: Jul 2006
Hey Blue Shift, I'm attempting the exact same thing and I came to the same conclusions that you have. I found a 3.0L crank already machined for a Fiero block on Ebay and from another seller, I picked up some rods and .030 pistons from a 3.0L marine engine. So I have the entire rotating assembly to work with. I'm just looking for a '85-'86 block so I can mock this up and check block clearance.
Sweet, looks like you're a step or two ahead, without the distraction of having to build a normal duke in the meanwhile. I work at a machine shop, so I may be able to machine my own crank, however if you see another crank that's already good to go, let me know will ya?
When you have time to mock it up, let the world know - you'll get there before I do I bet.
Since your on the subject of 3.0L mercruiser cranks, Will an entire 3.0L mercruiser engine swap be possible? Pros, cons, what will work and what won't?
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85 GT 3.4 14.9 @ 90 1.9 60' Old TH125/3.06 Unknown New 4T60/3.42
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04:22 PM
patch Member
Posts: 210 From: Santaquin,UT, USA Registered: Jul 2006
Sweet, looks like you're a step or two ahead, without the distraction of having to build a normal duke in the meanwhile. I work at a machine shop, so I may be able to machine my own crank, however if you see another crank that's already good to go, let me know will ya?
When you have time to mock it up, let the world know - you'll get there before I do I bet.
Well..... we'll see. Those blocks aren't as easy to find up here as in CA (I'm from the Bay), and I do have several other projects going, but I definitely am trying to determine a game plan here. Other then block clearance the other unknown for me is compression ratio. I do have the D shaped dish pistons and not the flattops but I believe that merc 3.0 motors use a larger combustion chamber size ( 60-70cc?) then our crossflow heads do.
Ok... I've tried to post this 3 times now, lets see if I get it down this time.
Lilchief - Short answer, there's a few apparent differences with the 3.0L/181 Marine/Industrial engine:
-Head: it's non crossflow, so you'll have the exhaust and intake on the same sides. Though I've heard that a crossflow head from a Chevy 153 can be found that'll bolt on. I have no idea if an Iron Duke head will bolt up or not, though the 153 crankshaft supposedly will work in the duke if you machine the flywheel bolt flange just like the marine crank. Either way, you'll probably have to run a carb (or propane like the forklift 181 engines!). I doubt that Fiero accessories could be made to work.
Block - It's got the SBC bellhousing, so you'll need an adaptor plate and flywheel to make it work. The water pump is front mount instead of side mount like our engines, so you may need to bust out el senor sledgehammer, or the sawzall to get it to fit (like some of the SBC conversions), and figure out how you're going to route all the plumbing to make it work. One other thing, is that I have no idea what provisions are on the marine 3.0 block for engine mounts - you may have to fab custom mounts, though again, I don't know about that part.
Either way, in the Peoples Republik of Kalifornia all the technical issues may make it impossible to make the swap look legit enough to pass.
Patch - There seems to be a bunch of earlier duke blocks in the yards around here in the Yay Area, and I'll be pulling one from my car as soon as my interim engine is ready to go in. Looking at the 90' block I have, it looks like there's huuge room for some extra crank stroke - there should only be ~.300" more clearance required to make it happen, not counting bigger rods and more angularity. I don't think it'll be a problem, but I'll toss the crank back in and take some pics.
As for compression, go to the Keith Black/Silv-O-Lite piston page and check out the marine piston specs. They also show a flat top piston for the early Iron Duke engines... wonder if we could use them without winding up with 10+:1 CR? Worst case, why don't you just use some nice new hypereutectic 2.5L pistons? The piston pin is .927" for both the 2.5 and marine engine, I believe so it should work fine.
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09:20 PM
Jul 27th, 2008
patch Member
Posts: 210 From: Santaquin,UT, USA Registered: Jul 2006
Don't use the KB 151 flattops unless you're running race gas. I tried those pistons on the first 2.5 I built for my Indy. I miscalculated the size of my combustion chambers and wound up with way too high compression ( I est around 12:1 with 45cc cyl head chambers). Those early non-crossflow dukes used much larger combustion chambers as did the boat motors from what I can gather. I did go to KB's page and I discovered my 3.0L D-shaped pistons use a 14cc dish. I wonder what the dish cc is on a stock Fiero 2.5 piston? I searched several sites but could not find the answer to that one. I also wonder if the stock 2.5 pistons would work with the differences in rod length and stroke?
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07:27 PM
Lilchief Member
Posts: 1738 From: Vevay,Indiana Registered: Feb 2004
Blue Shift, since I got an 88 with a bad 2.5 and trying to decide what engine to replace it with this subject might be the key. So I did some research and here's some questions I came up with. Will a 87 3.0L mercruiser crank work in a S-10 block and will it be compatible with my 88 ECM ? I'm trying to get gobs of low end torque and gas mileage. Also want a 4T60 to help acheive my goal and run on 87 octane
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85 GT 3.4 14.9 @ 90 1.9 60' Old TH125/3.06 Unknown New 4T60/3.42
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09:42 PM
Jul 28th, 2008
The_Stickman2 Member
Posts: 1030 From: Lehigh Valley Pa. Registered: Sep 2007
Hey I recognize that pic. Anyway I have said this before but it bears repeating. If you want a 3.0L marine crank cheap. Go to a marine/boat shop and see if they have any junk engines laying around. The one by me had two Marine 3.0L engines. One with a holed piston the other a cracked block from poor winterization. They told me they don't repair engines like this just replace them. So buying a new crank simply isn't that easy. Anyway I asked if they had any broke ones around and they told me of the 2 out back. I asked how much and the reply was $50 each. I bought them both. You won't break these cranks. Now the question of building a 250+hp engine with one of these cranks and an S-10 block. Completely feasible if you use a Super Duty head. Remember that the S-10 block has the same main cap webbing as the Super Duty block. The difference really in the two is the lack of provisions for a side mount water pump. And the alloy used in the casting. Aslo remember that the Indy Fiero made 232hp using an early head, 2 barrel intake(some say with a 2bbl carb others say with a TBI), and 2.7L crank. And it was a pretty mild build.
Also remember that the Indy Fiero made 232hp using an early head, 2 barrel intake(some say with a 2bbl carb others say with a TBI), and 2.7L crank. And it was a pretty mild build.
John Callies spoke at the 25 Anniversary banquet last night, and he said it was done on the dyno with a carb initially and that the Pace car actually ran at Indy with a TBI unit calibrated primarily off of the fuel consumption data recorded on the dyno.
I did some more research today, as well as taking measurements from my ongoing 1990' Vin R engine rebuild (Iron Dookie, I'll call that one).
Patch - I bet you're right about the flat tops - they're not only flat top, but I believe they have a 1.6" Compression Height, as well. That's going to make too much compression, though I bet it had nice quench... To answer your question about the GM stocker pistons, I took a look at the number on the stock cast units on my 90' engine: 10042076. Looking it up on Google, I found a Silv-O-Lite catalog page that says the following:
15cc it says. But keep in mind that the marine 181 pistons also seem to have a 1.625" Compression Height as well, while all the stock pistons and replacement pistons for the 151 are listed as 1.56" CH. I took a "real world" measurement today by installing one rod and piston and bringing it to TDC, and got a measurement somewhere around ~.040" below the deck as it sits. The 181 pistons supposedly sit .065" taller so they'd be out of the hole .020 or .030 if my measurements are anywhere near correct. The head gasket I pulled off seemed to measure somewhere around .038-.040" at the fire ring. I'd say you'd want to get no closer than "0 deck" to get around .040" piston to head clearance for maximum quench effect - where air/fuel in the combustion chamber gets squeezed between the flat rim of the piston and the flat surface of the head inside the cylinder surrounding the combustion chamber and is expelled into the combustion chamber, cooling hot spots and stirring up the burning mixture. The result is more detonation resistance, which is good when going for more compression.
Anyways, compression and quench aside, the math I did seems to suggest that a 5.7" rod on a 3.6" stroke crank raises the piston to the same height as a 6.0" rod on a 3" stroke crank, which isn't a coincidence. You should be able to put stock 151/Fiero pistons on the marine rods and crank and go to town! My only question is whether a nice small block piston exists of the "D dish" shape, where the flat pad will end up at 0 deck, while overall compression ends up at no more than say, 9.5:1? There's a huge variety of SBC pistons of 4.0" bore, and 1.56 CH, which can be had in D dish configuration. I'll look into it tomorrow.
Lilchief - As much as I hate to say it, I'm not aware of a Mercruiser or industrial 3.0L crankshaft that has the drive gear for the force balancer/oil pump, nor the DIS trigger ring (on the side of the drive gear) - I believe they're all set up for earlier distributor use - it should work in an 86 and down engine, but 87' and up will prove impossible due to the lack of distributor provision on the block. As for the S-10 block, I've read that the RWD blocks are no less POS than the FWD blocks (which would negate the rumor that they're cast just like the SD blocks, minus the nicer alloy), and that they lack the provisions for a side mounted water pump that we require. Strangely, there seems to be provisions for front and side mounted water pumps on the 1990 engine I have, I'll post pics in a second. I'm planning on using an 86' distributor driven engine, Mercruiser crank, and a 440T4 4 speed "dumb" automatic eventually for my Super Dookie 4 project. I also want to see if I can take the D port head on this 90' engine and bolt the whole top end to an earlier lower end, using some creative wiring to make it work.
Stickman - I'll probably call around and see if they have any frost cracked 3.0's laying around. The 307 in my old boat died (sort of, we ran it till it spun a bearing, and it took 2 seasons), so it can't be that uncommon - good idea. As for the RWD S-10 or Astro block, I've never seen one in person, but I've read that they lack the provisions for the right water pump, and I'm not sure if the front mount pump will clear the frame rail. But more importantly, later S-10 blocks are DIS, and won't have a distributor drive that you'll need to run the 181 crankshaft - none of the marine or industrial engines were ever DIS, right? I've heard of an Astro block that had the provision for a side mounted pump, but can't confirm this. The key may lie in finding an earlier distributor block, or there may be no truly strong block available at all.
Anyways, back to the Iron Dookie project - I've been tearing down and inspecting a 1990' Vin R 2.5 out of an Olds Cutlass Ciera. It seems to have a lot of refinements and nice features over my tired 86' 2.5, including a supposed 110HP vs my 92. It is truly too bad that the 181 crankshaft doesn't have the force balancer/oil pump drive gear/DIS setup, because this would be a great candidate for it.
Bottom end opened up - I've never seen the force balancer/oil pump assembly. GM afterthoughts at their finest!
The heart of the gerotor style oil pump hidden in the force balancer assembly - looks perfectly fine after all those miles.
The 90' block isn't that strong either, but it may be thicker cast than my 86' engine.
Water cooled timing belt tensioner! Is this a provision for a RWD water pump? Or is it a way of generating massive coolant leaks?
Piston at TDC, notice that it's in the hole by about that much.
Stock bore still.
Not too much wear, really. I'm really surprised.
Now, assuming the early blocks are similar, if not the same, there's a LOT of room around the crank for more stroke: The crank misses all the potential collision spots by a mile... it shouldn't be a problem for a 3.6" stroke crank vs the 3.0" stock crank stroke as it's only .300" more I think.
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02:45 AM
KurtAKX Member
Posts: 4008 From: West Bloomfield, MI Registered: Feb 2002
Originally posted by Blue Shift: You should be able to put stock 151/Fiero pistons on the marine rods and crank and go to town!
I'd double-check that if I were you. Shorter rods + bigger counterweights usually = trouble in the area of piston skirt to counterweight clearance.
quote
Originally posted by Blue Shift: Lilchief - As much as I hate to say it, I'm not aware of a Mercruiser or industrial 3.0L crankshaft that has the drive gear for the force balancer/oil pump, nor the DIS trigger ring (on the side of the drive gear) - I believe they're all set up for earlier distributor use
That would be correct.
quote
Originally posted by Blue Shift: I'm planning on using an 86' distributor driven engine, Mercruiser crank, and a 440T4 4 speed "dumb" automatic eventually for my Super Dookie 4 project. I also want to see if I can take the D port head on this 90' engine and bolt the whole top end to an earlier lower end, using some creative wiring to make it work.
Yes, you can do this. You just have to make sure you use the pushrods that match the year of the head you have, since there were at least 4 different pushrod lengths. The wiring won't even have to be that creative. I have in my garage right now the wiring harness from a 91 S10. When you use this harness, you gain the newer faster better P4 ECM and the distributor connector is correct to work with 84 (not 85 or 86) Fiero distributors. I am working on this right now for a '6156 to '7165 ECM swap kit.
quote
Originally posted by Blue Shift: none of the marine or industrial engines were ever DIS, right?
Correct.
quote
Originally posted by Blue Shift: there may be no truly strong block available at all.
If I understood John Callies correctly, the Fiero Pace Car that ran at Indy in 84 had a SD head on a stock block and it was good enough to make 232 HP at 6500 RPM. I don't think the block itself is very often the problem- mostly the cranks.
quote
Originally posted by Blue Shift: I've never seen the force balancer/oil pump assembly. GM afterthoughts at their finest!
Actually, development work for the 2.5 Pontiac force balancer was presented at SAE World Congress as early as 1984. Its what's known as an Oldham style balancer.
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03:18 AM
KurtAKX Member
Posts: 4008 From: West Bloomfield, MI Registered: Feb 2002
Originally posted by Blue Shift: Anyways, compression and quench aside, the math I did seems to suggest that a 5.7" rod on a 3.6" stroke crank raises the piston to the same height as a 6.0" rod on a 3" stroke crank, which isn't a coincidence. You should be able to put stock 151/Fiero pistons on the marine rods and crank and go to town! My only question is whether a nice small block piston exists of the "D dish" shape, where the flat pad will end up at 0 deck, while overall compression ends up at no more than say, 9.5:1? There's a huge variety of SBC pistons of 4.0" bore, and 1.56 CH, which can be had in D dish configuration. I'll look into it tomorrow.
Water cooled timing belt tensioner! Is this a provision for a RWD water pump? Or is it a way of generating massive coolant leaks?
www.summitracing.com has a good selection of pistons and a passable parametric search engine. You have to dick around with it a bit (select enough other variables to make CH pop up) but once you're there it shouldn't be any trouble to figure out if they have a piston for you or not. You also might want to look at using 6" rods with the 3.6" crank because there might be something in the 1.3xx CH range that would work with that combo. The longer rods will increase the mechanical efficiency of the engine and help with that gas mileage you're looking for. I didn't realize that Dukes had rods that long. That's pretty wild. That's a 2:1 rod ratio from the factory... no wonder they get great mileage. They can probably also stand some pretty high compression with the stock geometry.
Yes, that's a provision for a front mount water pump. AMC inline 6's have a setup VERY similar to that.
Originally posted by Blue Shift: Not too much wear, really. I'm really surprised.
EFI engines (even TBI counts) last MUCH longer and wear MUCH less than carbeuretted engines because they have MUCH better mixture control in a cold engine and don't wash the bores down on cold start the way carb'd engines tend to.
I listened intently to Callies speak, very entertaining and fairly info-dense. When he mentioned the block he basically said it was marginal, and he didn't really say what they did, other than to off-handedly mention that they changed the head bolts to 1/2" to increase clamping force as the original bolts weren't strong enough. They also used custom head gaskets. Also, I thought I heard him mention something like 250HP and 215 ft.lbs. of torque in the end.
JazzMan
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01:26 PM
The_Stickman2 Member
Posts: 1030 From: Lehigh Valley Pa. Registered: Sep 2007
BTW I have heard that some FWD dukes are shorter. I think the Calias(Grand-Am style cars) are the ones with the shorter engines. So some measurements may be off. I have also heard of the AstroVan block that has the main cap webbing of the S-10 but the provisions for the side mounted water pump. Again from what I have heard they are in corporate vans like used for utliites and such. I do beileve that adding a Marine crank will significatly increrase the bottom end strength. Wait till you try and pick one up.
BTW I have heard that some FWD dukes are shorter. I think the Calias(Grand-Am style cars) are the ones with the shorter engines. So some measurements may be off. I have also heard of the AstroVan block that has the main cap webbing of the S-10 but the provisions for the side mounted water pump. Again from what I have heard they are in corporate vans like used for utliites and such. I do beileve that adding a Marine crank will significatly increrase the bottom end strength. Wait till you try and pick one up.
VIN U Dukes are in fact shorter. They lack the bosses in the casting for the Fiero/A/X car style engine mounts. They can be identified by unique block and head casting #s, or they can be identified by the casual observer by noting the oil filter pad orientation. The "regular" length 2.5s have the oil filter sticking out the side of the block, whereas the short VIN "U" engines which came from N body cars have the oil filter pad facing vertically (up)
I knew a guy some time ago who had a 2.5 Astro Van. He said it was good for 55-60mph max. It was a retired US Postal vehicle if that helps give you any idea of where to look for 2.5 Astros.
Does anyone know the break years for the casting styles of the 3.0 crank? I have a 499311 crank (the "good" one Lloyde refers to in his 2002 post about a 195HP Duke) and I don't see how you could ever get it to work.
The "new" style 3.0 marine crank looks like it has more meat so it could be cut down to work.
The Vin U dukes are shorter. The ones I saw at the yard even looked a tiny bit shorter, unless it was my imagination.
I do still wonder about the Astro blocks. Having yet to crawl under an S-10 and pull the pan, I have no idea if the S-10 block being thicker is an unsubstantiated myth, or that certain or all years actually do have thick main webs. It would make sense for a heavy duty/fleet vehicle, it seems. I wonder what block the Grumman LLV postal vehicle uses, or if one could even get ahold of one? It's listed as a TBI 2.5. Seems that the rods are pretty frail, and that when connected to a weak, flexible crankshaft, they tend to depart the block when pushed hard. As Callies may have been aluding to, it's a possibility that a good stock block could handle 200+hp, at least for awhile. Should be fine for the comparatively wimpy numbers I'm expecting. But it'd be kinda cool to have a SD like shortblock, no?
Will - the only problem is that the duke rods are total pieces and incompatable with the Mercruiser crank rod journals... But the solution seems to lie in 6" aftermarket Chevy I-6 rods - Summit has them, and the big end width is correct and everything. Actually, I wonder if Chevy 292 inline 6 rods are 6"? I've worked out what seems to be a viable solution: - Modified Mercruiser 181 crankshaft (3.6" stroke) - 6" aftermarket Chevy Inline 6 rods (6.0" long 1.029" big end width) - Small Block Chevy 1.26" CH piston
Keith Black 731 is a forged step dish piston of 18cc D shaped dish - I have the same pistons (but diff CH) in my 383 on my boat - very nice pieces for the price. The bigger dish should allow me to deck some more material off of the block to get closer to 0 deck, leaving the .038-.040" thickness of the gasket to establish quench clearance. There may be a similar piston configuration in 22cc D cup style that'd allow more decking before going too high on compression - since there's no knock sensor, it'd probably be a bad idea to crank it up too high on compression. I'll figure that part out when I haven't been awake for as long as I have. But there's one more thing to consider - even though it all looks like off the shelf hardware, and no creative machining (aside from the crank), that's still a lot of money for the bottom end on an unproven block, without a head that will flow as much as custom rods, forged pistons, and a brawny crank can take. I could see topping it off with a super duty head, though. Depending on how much I want to sink into the Super Dookie, I may end up using stock Mercruiser parts, with fresh hypereutectic 2.5 pistons in order to cut costs waaay down just to prove the concept. Were I not planning to build up a 3.1L TGP engine later on, the idea would be more attractive. I'd like to think the cheap Fiero owner mentality doesn't apply on the grounds that I'll eventually have built 3 engines for this car by the time I'm done!
Kurt - From taking a look at the stock duke crank, it appears the rear mean sealing surface is notably larger in diameter than the bearing journal surface - where on the early 3.0 crank, they appear to be fairly similar in diameter. I'm not sure there's enough meat to form the appropriate shape, looking at pictures, though I don't have one in hand to mic up and see for myself. The later year crank seems to have been sucessfully machined down and redrilled to work, so that would be the one I'm leaning toward, myself. I figure that even if you cut into the old SBC bolt hole pattern, you could press on a repair sleeve so the rear main seal has something to engage?
Alright... time to stop thinking about iron dukes and sleep instead!
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01:54 AM
PFF
System Bot
Will Member
Posts: 14250 From: Where you least expect me Registered: Jun 2000
Originally posted by Blue Shift: There may be a similar piston configuration in 22cc D cup style that'd allow more decking before going too high on compression - since there's no knock sensor, it'd probably be a bad idea to crank it up too high on compression.
Switch it over to 7730 with the $8D code and cylinder select set to 4, then run a knock sensor.
Remember that at $4+/gal, the cost per mile of a high comp engine that runs only premium is LOWER than the cost/mile of a low comp engine that can run regular. Compression can be your friend.
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10:53 AM
KurtAKX Member
Posts: 4008 From: West Bloomfield, MI Registered: Feb 2002
Switch it over to 7730 with the $8D code and cylinder select set to 4, then run a knock sensor.
Remember that at $4+/gal, the cost per mile of a high comp engine that runs only premium is LOWER than the cost/mile of a low comp engine that can run regular. Compression can be your friend.
I know there are versions of P4 code out there where changing the cylinder select actually screws up some of the calculations; is the $8D one of them? $8D runs with a distributor originally right... a TPI code?
If you can jockey the code, I can put together some harnesses to test this.
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12:54 PM
patch Member
Posts: 210 From: Santaquin,UT, USA Registered: Jul 2006
+ for really good info Blue Shift. I allready have the 3.0 pistons pressed on the 3.0 rods, so when I do find a block I'll mock it up and hope they don't stick out too far. On a side note, the flattop KBs I used also have a 1.6CH and I didn't have any clearance issues with them, just way too high comp. Since my D dish 3.0 pistons are 14cc and the Fiero 2.5 are 15cc I think I'll be okay.
I guess I'll get my chance to visist the junkyard again this weekend... My 90' 2.5 head is cracked - the middle of the cylinder head on the exhaust side looks like it got way toasty as there's burnt, coked oil in the valvetrain area where oil should have been flowing... The valve stem seals have burnt to a (semi) crisp on the middle exhaust valves, and theres a fat crack between the intake valve seat and spark plug on the middle cylinders. I guess I know what did that car in!
I'm going to try to find another late (90+) vin R head to replace it, during which time I'll explore and see if I can find anything related here.
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10:40 PM
Aug 2nd, 2008
KurtAKX Member
Posts: 4008 From: West Bloomfield, MI Registered: Feb 2002
Additional self bump... Been tied up in the Iron Dookie project, going to the car yard tomorrow to hopefully pull another late model, D port head. I have a rebuild kit ordered for the otherwise healthy 90' motor and the like.
I guess I'll start mocking up parts when I pull my 86' engine out and have my commuter running solid. I'm going to try to look for S-10's or anything RWD in the yard to see if I can pull pans and water pumps off and determine the truth about how their usefulness for the Super Dookie project.
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10:49 PM
Aug 3rd, 2008
fierodeletre Member
Posts: 834 From: Behind Animal's Drum Set. Registered: Oct 2006
Blueshift- Thanks for doing this and doing it so pictorally! I think with gas where it is, our dukes as old as they are, and as frugal as fiero guys can be, this will be a much-watched swap thread. There are only two things that make me want to work on a duke: 1, availability and cheapness of parts, and 2, for as worthless as it is in the hp and tq department, the little guy DOES sip at fuel. This sounds like you might be on to a somewhat easy way to accomplishing the merc swap. I'm on board, I think there are lots of us out there who are too. Keep it up!
------------------ I have no more fieros. Eventually all the things you love will go away.
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07:13 AM
jetman Member
Posts: 7794 From: Sterling Heights Mich Registered: Dec 2002
Bookmarked this thread also. I've always been fascinated with what you folks with the knowledge and skills can do with the 4-cylinder engines. Look forward to seeing somebody get the details worked out so I could try this myself someday.
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09:48 AM
jetman Member
Posts: 7794 From: Sterling Heights Mich Registered: Dec 2002
, , , , , However, on further inspection, the head has "D" shaped exhaust ports, and the intake manifold has a divorced water passage (to keep the air/fuel in the adjacent runner cooler) - exactly the same as detailed in this thread: https://www.fiero.nl/forum/Forum2/HTML/074087.html
What a lovely day I had at the yards today. I've learned a few things:
1.) All S-10's or S-15's at the junkyard are stripped devoid of their drivetrains the moment they touch down, by law. 2.) All Astros are 4.3L. Period. 3.) All vin R cars are 1988 and down. All vin U cars are 1990 and up. 4.) 1996-1997 3.4L DOHC's only show up in the yards after long days of fruitless searching, but when you find they won't take ATM cards at the window. Damn.
But I bought a sweet pair of GMPP crinkle finish valve covers for the 383 for my boat on the way to the 5 diff yards I went to... I convince myself for my sanity that it was a productive day due to this.
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01:11 AM
PFF
System Bot
AquaHusky Member
Posts: 1234 From: Sedalia, Mo Registered: Dec 2006
What a lovely day I had at the yards today. I've learned a few things:
1.) All S-10's or S-15's at the junkyard are stripped devoid of their drivetrains the moment they touch down, by law. 2.) All Astros are 4.3L. Period. 3.) All vin R cars are 1988 and down. All vin U cars are 1990 and up. 4.) 1996-1997 3.4L DOHC's only show up in the yards after long days of fruitless searching, but when you find they won't take ATM cards at the window. Damn.
But I bought a sweet pair of GMPP crinkle finish valve covers for the 383 for my boat on the way to the 5 diff yards I went to... I convince myself for my sanity that it was a productive day due to this.
1) Must suck where you live. Why do the strip them out? 2) Not true. 99% of them are 4.3 equipped. I've run across about 3 Astro/Safari vans with the 2.5, and two of them had a 5 speed. They had an odd factory adapter that moved the shifter to the left. 3) I thought the larger FWD cars are VIN R cars and smaller ones are VIN Us. 4) Places keep costs down by operating cash only. Each transaction costs the place money. Oh well I guess. That's why I'll always carry cash on me.
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10:47 AM
Aug 5th, 2008
Lilchief Member
Posts: 1738 From: Vevay,Indiana Registered: Feb 2004
So would a mercruiser early model (89-down) 2 piece rear main seal crank work in a 90s model 2.5 with some machine work done? Also why couldn't you install an external crank trigger?
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85 GT 3.4 14.9 @ 90 1.9 60' Old TH125/3.06 Unknown New 4T60/3.42
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07:40 PM
KurtAKX Member
Posts: 4008 From: West Bloomfield, MI Registered: Feb 2002
Joking about all of the above, making light of a bum day at the yards. Dunno what the deal was with S-10's and S-15's, they were almost all empty of motor and trans. The mexicans LOVE them for utility work - there's probably a high demand for replacement engines for them and stuff, explaining how quickly they got stripped out. I thougth I stumbled on a carbureted duke, but on further inspection, it was a 2.0. Anyhow, I saw everything cool at the yard I couldn't use - loads of Northstars, LT1's, DOHC 3.4's, quads, etc, but there was no good VIN R late model duke stuff! So strange. Husky - do you remember any of the details about the 2.5 Astro? Did you happen to look at it closely and note how the water pump is, the block, etc?
Chief - I think you'll want a late model crank... Going by eye, there doesn't seem to be enough metal to form the duke rear main sealing surface from, though on the late model crank, you'll need to machine off a good chunk of metal to bring it down to the right size - easier to cut metal off than to put it on!
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12:28 AM
FieroBrad87 Member
Posts: 743 From: Nevada, Iowa, United States Registered: Dec 2005
So I was at work a couple days ago, taking apart LS6 cylinder heads to do some machine work (I work for a race engine shop as a rookie machinist), when I got a crazy idea. So I asked what they do with the stock springs and it turns out they toss em in a bag and shelf em, never to be seen again. So today after work, I hit the engine build room and took some measurements on the spring machine:
2.5 Stock Spring, very tired after 18 years of use: (All measurements approximate - done with a beater caliper) ID: .900" OD: 1.237" Length: 2.095"
Coil bind @ .935" total, approx. ~.580" from installed height to bind. ~126lbs on seat, ~252lbs @ .350" lift
So yeah... This is what happens when I get bored after work. I also forgot to mention that the 2 center most stock exhaust valve springs on the cracked head had taken a .100" set! That cylinder head must have gotten very, very hot to make a thick layer of coked up oil and to flatten the valve springs, man. Anyways, LS6 springs and retainers look like they'll physically fit the iron duke head, and it's not like they'll ever come close to coil binding with the dukes wimpy cam lift. The question, is whether the cam (and its 3 bearings) and stock lifters will tolerate so much extra pressure. And unless you're spinning 7 grand, you won't need so much spring, but hey at least valvetrain float would be a non issue! On that note, I wonder what other GM cylinder heads I could install them in...
[This message has been edited by Blue Shift (edited 08-08-2008).]
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12:24 AM
KurtAKX Member
Posts: 4008 From: West Bloomfield, MI Registered: Feb 2002
So..... any updates? this is a bump. and just to kick some ideas around, is the consensus that the weakest link of the stock duke is in the crank and rods? Has anyone cracked a block and NOT the crank or rods? I know the block is supposed to have thin walls. But does it really? Are they really that weak? Do you think this block could stand up to 3.0 liters of stroke and higher compression if the rods and crank were bulletproof? If so, and a way to increase head flow (without going the SD route) could be found, couldn't one conceivably attempt to mildly turbo such an engine? What do you think the HP/TQ ratings would be, even if it were NA? And the famous duke fuel mileage? Would you have to carb it, do you think? Or could one adjust the TBI to put out the proper amount to compensate for the increased displacement?
------------------ Kermit- "So you like your drums huh?" Animal- "Oh yeah! Mwah Mwah Mwah" (kissing drum set) Kermit- "Uh huh. More than food, huh?" Animal- "They ARE food! Eat Drums! Eat Cymbals!" (eating noises) Kermit- "Hm. How 'cymbal'-ic!" Animal- (looking abused) "BAD PUN!"
Gonna go hit the other yards tomorrow... I should go and see if I can find a truck or astro block and get a good look at it up close.
I have yet to hear of somebody destroying an engine due to the block, though extra beefiness certainly could not hurt. I personally think that the rods are frail and when coupled to heavy, brittle 4" bore pistons and a rubber band for a crank, parts tend to depart the block when you push it too hard. I bet a stiff, balanced crank and good heavy duty rods would be a big fix. The best solution would be a brawny block (if the RWD blocks prove to actually be stronger), Merc crank, and forged 4340 aftermarket 6" rods for the chevy I6, and some forged SBC pistons. Now you just need a decent head and you'd be doing pretty well, I think.
this is a bump. and just to kick some ideas around, is the consensus that the weakest link of the stock duke is in the crank and rods? Has anyone cracked a block and NOT the crank or rods? I know the block is supposed to have thin walls. But does it really? Are they really that weak? Do you think this block could stand up to 3.0 liters of stroke and higher compression if the rods and crank were bulletproof? If so, and a way to increase head flow (without going the SD route) could be found, couldn't one conceivably attempt to mildly turbo such an engine? What do you think the HP/TQ ratings would be, even if it were NA? And the famous duke fuel mileage? Would you have to carb it, do you think? Or could one adjust the TBI to put out the proper amount to compensate for the increased displacement?
