yes i like the standard shift better but if the car handles better with it in the longitude configuration not that it will and is less likely to break a trany when hammerd on and you can get a big block in there easyer sound like the way to go of course it needs to be proven on all acounts
425s are the hardest to find, and most desireable. price really depends on what condition its in and how much it is worth to you over the next guy. how much is he asking? is it complete? and does it need rebuilding?
------------------ 1986 Silver 5 speed Fiero 3.4 DOHC Bored .30, Fully balanced and blueprinted 13.93@101mph as it is on the street. PFF's fastest N/A 3.4dohc!!!! FOR SALE - MAKE OFFER! ... ... ! 355cid 400hp/tq N/A SBC, 4 bolt main Nitrous Oxide: 1st stage - 125shot direct port. 2nd stage - 75shot plate. 87 GT, Cryo Treated 5-speed Getrag, Gr8grip LSD, Spec Stage 3 clutch.
My understanding is that there is a difference in the early transmissions ~1967 that make it worth more. They are easier to do a reverse rotation on.??
I thought that the 325 where the easy ones to revers rotate street dreams makes a addaptore for the 325 but the 425 is like a tubo 400 realy strong and the 325 is like a turbo 350
If i dont buy the whole car and get just the trany what big block would you like to see in the car these are the options buick oldsmobile pontiac cadillac chevy mopar 392 hemie
most popular are the caddi 500 or 472 (?), or big block chevys. the caddi motors will bolt up without any modifications to clear the axles but the BBCs need to clearance the oil pan for the axles.
------------------ 1987 Pontiac Fiero GT 418ci 'Mini-Rat' motor dual stage nitrous injected built 5-speed getrag
Ya i know just having some fun I had a early 392 hemi from a 58 300 C I dont realy think it would fit in the car they sre so wide but i like the buick engine big bore shoter stroke or 427 chevy
width shouldnt be an issue with a longitudinal swap, the only thing to measure for would be the strut towers but those should be plenty wide for most any engine. a 392 hemi sure would be an interesting fiero swap! is the bolt pattern the same as a BBC? and are the main journals in the same spot as a BBC? you will have to clearance the oil pan with that motor like a bbc.
------------------ 1987 Pontiac Fiero GT 418ci 'Mini-Rat' motor dual stage nitrous injected built 5-speed getrag
[This message has been edited by RichLo (edited 01-07-2008).]
well found some tranys for cheaper money from 150 to 350 not sure when the TH 425 was not put in and when the TH 325 started to be put in I would like to sell the car I was going to use it is a T TOP dont think it will like the Big block might have to much flex pluse some many think the T top cars are to not be tuched
Thanks opm2000 I found some 425 tranys cheap I think that i will not do the revers rotation I just will need to add some wight to the front to get a 50/50 wight or get it closer the car itself is going to need to get a cage to stiffen it up for the extra power
Ok i have been looking at engine combos I think a 403 Oldsmobile with a olds 425 crank that will make 480 inches I will need to put a stud girdle from mondello on it but is fixes the oil pan problem and it should be better than a 455 due to it will be a big bore short stroke engine or i can use the 350 disel block and make 440 and the engine would not wigh anymore than a SBC
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09:33 AM
ducattiman Member
Posts: 674 From: TheNetherlands Registered: Mar 2003
John miller was having problems getting the axle threw under the oil pan and I don't know if he ever succeeded. Big blocks make more torque which is harder on trannys so I really doubt that transversed setup is a good idea. At this point in summary it seems that other engine choices would be more practical then a big block chevy.
Weight seems to come up as a topic and the chevy is heavier then most all of the choices suggested on this thread other then the 392 hemi. I had one in a gremlin and man was it heavy. The cadillac is the lightest and with some parts changes is close to the weight of a small block chevy. The olds isn't that much heavier then the cadillac and it goes in just as easy. For those that are concerned with weight here is the cadillac weight breakdown.
Put on an aluminum intake, a high torque mini starter, a 425 balancer, and a 12" switch pitch converter like mine and you will shave off another 45 lb. Read about this in my trashed thread "building a big block fiero".
------------------ the only fiero's running 10's have longitudinally mounted drivetrain, and the handling is pretty good.
[This message has been edited by big block fiero (edited 01-15-2008).]
I checked on the 403 oldsmobile wight and it said 550 lbs and the SBC wight was 575 lbs so i will be looking into that engine i know about the mian web problem but mondello has made a girdle for them
Is there a posi unit for the TH 425 is there gears for it like 390's
Theres no posi available that I know of but with good tires you wont need it. I out launch almost everybody I race with crappy radials while they have slicks.
Do you really need 390 gears? The deepest (and strongest) gears available are 321 but there hard to find, I have a few sets, You can get deeper ( high 3 and 4 series) gears but they are very expensive . You cant get a very tall tire under a fiero, mine has 2.73"s in it.
I checked on the 403 oldsmobile wight and it said 550 lbs and the SBC wight was 575 lbs so i will be looking into that engine i know about the mian web problem but mondello has made a girdle for them
Olds motor is a good choice but are you sure its really that light. I have a 455 with "c" heads in my sons fiero.
the olds 403 is a small block engine based on the 350 rocket but with 4.351 bores and the gear thing your corectt prob wont need that much gear i am also looking int to the cadi 500 i see there making some parts for it one site has a cam out 500 HP 600 foot pounds of tourque that oghta get things moving like the earth lol
After looking at the Porsche 911 wight of 43 % front & 57 % rear wight and with the setup of just puting the engine in with out revers rotation it is like 60% rear and 40% front I figure if i can trim 75 lbs out of the back and add 75 lbs in the front I will be at 45% front & 55% reare so it should be able to get it to handle prety good with the right springs and swaybar i think i will have to go with coil overs
don't mean to hijack the thread, but this has got me thinking. I looked on car-part and saw many many TH425's for under $200...what do these transmissions handle for hp/torque? I know the engines in front of them (according to wikipedia) were rated at 500hp, so would 600hp/600tq be a safe estimate? that is enough to put a fiero into the 10's at least.
are there shift kits and performance internals for these things?
------------------ '84 Fiero....'95 Chevy Vortec 4.3L V6 Swap Under Construction Visit Project Website! http://cowan1984.xtreemhost.com/
the trany is the same as a Turbo 400 it just has a tranfer case and differential hooked to it so it can take prety much what ever you put to it as long as you build it up like the turbo 400 the best way would to be to buy a old eldorado with the 500 engine 70 to 76 then you will have allmost all the parts needed and you can get Hipo parts at this site http://www.mtscadparts.com
[This message has been edited by engine man (edited 01-19-2008).]
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07:18 PM
Jan 20th, 2008
opm2000 Member
Posts: 1347 From: Versailles, Ky USA Heart of the Bluegrass Registered: Dec 2000
I'm going way back, but wasn't there a guy named "Randy Corson" that also made V8 kits???
Joe
wow, I haven't heard that name in a long time. yea he made v8 kits but wasnt he mostly into turnkey complete cars? those are pretty rare cars to come by now.
------------------ 1987 Pontiac Fiero GT 418ci 'Mini-Rat' motor dual stage nitrous injected built 5-speed getrag
Ok I was thinking and wonder how much wight would be moved to the front end precentage by moving the engine a inch or two forward I dont think it will bothere the axles
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06:26 PM
opm2000 Member
Posts: 1347 From: Versailles, Ky USA Heart of the Bluegrass Registered: Dec 2000
Guyon's Performance fabricated that belt drive, before they went out of business. A lot of neat cnc & milling work....no telling what it cost.
Yes, it is installed in a Fiero, look carefully at the pic with the tail light harness. I have no idea who this was produced for, nor what the end results were.
BTW, I just don't think you can "scooch" the axels like you just mentioned. Built it right.
Ive got mine as far forward as I can, the water pump pulley is less then an inch from firewall mounted wiring harnesses and such. I could even go a little more forward but its just fine where its at. The axle angle isn't to severe.
don't mean to hijack the thread, but this has got me thinking. I looked on car-part and saw many many TH425's for under $200...what do these transmissions handle for hp/torque? I know the engines in front of them (according to wikipedia) were rated at 500hp, so would 600hp/600tq be a safe estimate? that is enough to put a fiero into the 10's at least.
are there shift kits and performance internals for these things?
The 1970 eldorado was underrated at 400hp and 550 foot pounds of torque so it will take quite a bit. All of mine have the stock chain system. With the built motor in my truck and serious abuse I have only taken out one chain but I think that was a fluke. I replaced it in 2000 with a used junkyard chain and it hasn't failed yet. Transgo makes a shift kit for the turbo 425.
Big Block Fiero what engine you runing in your car
500 caddy, multiport fuel injected, 11 to one compression running e-85, custom variable displacement valvetrain can run on four cylinders in street sleeper mode.
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