jjoey00

Hi, I need help. My uncle just bought an IROC with TPI and a six speed how can you tell weather its a 5.7 or a 5.0 with out removing the head to measure the bore. The guy he got it from said it was out of a 2001 camaro, but when i look at it i told him it wasn't and ls1. I know that some corvettes came out with TPI and six speeds. How can I tell where this set up is from.

stanghunter211

If the car was originally a 5.0, it is conceiveable that the guy just replaced the t-5 with a t-56. Alot of people do it. I seriously doubt its a 350 in there. Though it could be. If he went through the trouble of replacing a trans, he might have done it as well.
Obviously this is not an LS1. You'd know it if you saw it. The trans might be from a 2001, but they stopped using TPI in 92. And yes vettes had it(TPI), but they either had autos or the 4+3 trans. I don't think a vette came out with a t-56 until the LT1 debuted in 91-92.
I would double check everything and ask the guy for records or whatever he can supply. Sounds a little shady to me.

Will

jjoey00

The previous owner was a young guy, who traded in his car at a lot my uncle works at, he might of be lied to. He traded it for a nissan 240sx. The car is a 87 IROC that use to be automatic. My uncle said it has aluminum heads, but i didn't get to check, it was night and i was short on time. i'll find out more today when i see it in the light. thanks

stanghunter211

I am almost 100% sure that only vettes got aluminum heads. THey are very saught after. Sounds like the guys full of it. Check it out, go get a magnet and if it sticks to the heads, they are cast, if not, then that whole car has been thrown together. How does it run???

Will

jjoey00

I already got the magnet just waiting for my wife to come home so i could leave(watching my daughter). can't tell if it runs well, the wires are arching every where, even at the plugs, it was dark so you could see it(arching) alot. so he hasn't really got on it yet, he said he tried when he was bringing it home and it would die down when it was about to open up.i'll see how it was thrown together today, all we had last night was a lighter. thanks again

Colin91Z

Vettes had six-speeds starting in 89, but not t56s, they were ZF six-speeds. Look a the 8th digit of the VIN, that will tell you a least what the car had originally. If its an 8, it had a 350. If its an F, it had a 305. Its very unlikely that the six speed is from a 01 because they are harder to adapt to a pre-LS1 engine. More than likely, the trans is from a 93-97 f-body. You said the car was originally auto, so I doubt the trans is using a t-5 bellhousing and hydralics because its easier to swap everything from a 93-97 donar car. Hope this helps.

jjoey00

Okay, just came back and the heads are aluminum, they also have roller rockers. My uncle said from the harmonic balancer that it is a 350, i just don't know how that works. according to the vin# it had a 305. how can you tell the diffrence between a zf six speed and a t56. Could the heads be after market, or do we possibly have a corvette motor. Is there any other ways to tell between a corvette tpi or a camaro tpi besides the heads. thanks again

angel71rs

ZF is huge, probably wouldn't fit without massive mods to floorpan. Most likely a t-56 from an LT1. Same rear block pattern as L98. This is what a t-56 looks like:

http://drivetrain.com/gmt56inst.html