I own a 305 TPI IROC and a S15 I am rebuilding the motor in. I figure while I am at it I want to up the motor to a 3.1. Can I get a 3.1 crank from a junkyard and will it fit right in? Also do I need the con rods, or the con rods and the pistons or just the pistons? Where do you V6s? go for parts?

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1987 Black 305 TPI 5spd IROC, G92, 9-bolt 3.45, Lowered, Cat-back, Air Foil, Sub Frames, Huge sways........Wrecked by a deer.
Looking for a 1995 Honda CR125R in NJ or PA. I have one for sale...RRP Sleeve Job, Vertex Piston, New Sprokets and a x-ring chain, new botom end with crank...etc etc
look here
http://www.classifieds2000.com/cgi-cls/ad.exe?P1+C18+R100004616

AIM: IROC 5spd
http://www.geocities.com/chevy5spdiroc/87Roc.htm

for the same price, less work, take a 3.4 long block from a 93-95 camaro or firebird and it will drop right in. More power too.

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1972 Chevy Chevelle "Malibu"
Hooker Headers, Flowmaster 40 series mufflers, accel 8.8 wires,Edelbrock performer intake Edelbrock Carb, Msd Blaster 2 Coil, Torque Thrust "D" wheels
Click here for my Malibu information
In Memory of #3 Dale Earnhardt

Yes, Graeme is way correct.
I'll show him why, after I get my fuel pump swapped out, too!
Seek/search out 2.8 to 3.4 swap boogie from past thread by me, KED85.
Good luck.

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

I'm pretty sure the only change in a 2.8 to 3.1 was the crank; not the rods. 1989-up 2.8/3.1's received lighter, forged pistons. What kind of parts are you after? Engine rebuild kits can be found through PAW, or NorthernAutoParts...


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-Tom P (Hot rodded 1986 Firebird 2.8l)

I am not looking for a complete engine....only what ever it takes to get the 2.8 to a 3.1 and if that is too much f it and I will just to a rebuild of the 2.8.....Pistons, Rings, Bearings, Plugs, oil pump etc

Not worth it. Depending what year the truck is you'd be spending a lot more money than what you have in mind. Besides the 3.1 isnt really any better than the 2.8. The added torque-e-ness of the 3.1 isn't torque-e-enough to be worthwhile, while it looses the rev-a-bility of the 2.8.

I paid $800 for my running 3.4 40K motor.
I doubt your machine shop bill would be that low.

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

ok....i am gonna try this again....so all I need is the crank....the 2.8 pistons and Rods Will work....I am not tring to create a bullet proof motor here just something that is a tad more toquey(don't need revs in a truck, if I was looking for performace I would go and get a V8...there is no comparson(spelling). NOW I also don't care to go get a 3.4 becuase ther are 1000 around here...I can rebuild a 2.8 for cheap and figure I would put a 3.1 crank in there while I am at it seeing they are not much from a junk yard. NOW please answer my question and stop telling me to get a bigger engine. This is like the 305 350 383 400 debate.....you guys hate it when i saw get a V8 in stead of modding your V6 so just answer my queation.

...I thought I did give an answer?

Haaay, wait a minnit- what year is the S15 truck? 1982-1986 motors were externally balanced. 1987-up 2.8/3.1's were internally balanced, which meant an extra counterweight in in the center of the crankshaft. (The counterweight was notched for a DIS GenII ignition system, which isn't used in our f-bodies or your S15). I don't know truck knowledge, but if the truck's an '86, you probably won't be able to get a 3.1 crank in there, since the 3.1 was from 90-92, the block will need a spot for the extra counterweight.


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-Tom P (Hot rodded 1986 Firebird 2.8l)

dude you read that out of a book.

thank for the stright answer....that is what I was looking for...I will just rebuild the 2.8 it is not that big of a deal.

Actually I don't read anything in books about V6's cause it doesn't really apply to what I'm working on. My statements are based in my experiance owning, and driving 2.8 and 3.1 powered cars, as well as experiances of people I know that own Fiero's. For all intents and purposes the 2.8 and 3.1 are virtually equal when it comes to actually applying their power.
Regardless, back to the topic, changing the crank in a 2.8 to a 3.1 crank would be a major ordeal that would involve more custom machine work then rebuilding the 2.8.

What kind of machine work? It's gotta be an 87-up block b/c of the counterweight. Plus, by '87, all the 2.8 blocks were large-journal'd. What else would there be?



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-Tom P (Hot rodded 1986 Firebird 2.8l)

What year did the S15 go out of production? My understanding is they were discontinued mid-80's.