Tonyy_z

Hey guys I just bought an 86 iroc. One of the previous owner pulled stock 305 tpi engine out and put in a 350 l05 from an 88 truck. The block has the l05 heads which I see are garbage the engine has tpi set up with it instead of the tbi though. I'm looking into changing the heads any idea what heads would bolt right up without modifications or any suggestions in which route to go. I dont want to get an ls engine money is limited but while I have engine out I'd like to at least give the engine some upgrades if it's worth it.

sofakingdom

iTrader: (1)

Best stock junk heads you can get, in an overall way, are the ones from 96-2000 350.

You'll have to get a new intake at the same time though. Which if it's still TPI, is arguably not worth it. The question then comes down to, do you want to leave it that way; or are you willing to put some kind of better intake on it. A Holley Stealth Ram for example.

Tonyy_z

Ok sorry if I have a lot of questions but this is the first time I have done a project like this. So if I change the heads I'll have to get different intake which will result in whole new fuel system as well since it wont be compatible with the tpi. Or is there an intake that will work with different heads and be able to leave the tpi system on there.

Fast355

iTrader: (2)

The best stock heads that will bolt to his TPI without changes are either the TBI truck heads or the TPI/Marine/Crate engine 350 heads ending with casting numbers 083 or 217. The TBI truck heads actually work very well with a stock TPI intake and a small cam.

Tonyy_z

thanks do you know what cam that would be. It has the stock 350 tbi heads if I can get away with just changing the cam and leaving the stock tpi intake. That would be awesome and still make better power without breaking the bank.

Fast355

iTrader: (2)

I would not spend a ton of money on the cam. Something like a Summit 1102 or Summit 1103 or the equivalent Mellings or Federal Mogul equivalent would work nicely. A set of generic cheap Z28 valve springs should drop on and I would address the valve stem seals at the same time.

Tonyy_z

are these supposed to be better than lt1 cam that everyone says to get ? I just checked summit but those part numbers say the highest year they will fit is an 86 sbc. The block I have is off an 88 . Will that make a difference?

Fast355

iTrader: (2)

A SBC 350 is a SBC 350 as far as a cam goes. As long as the lifters, timing set, and pushrods match you are golden. Roller cam is where things get complicated. A 1988 truck should have a flat tappet cam in it. The 98 305 Vortec I had in my 1999 Tahoe had a flat tappet cam in it, FWIW.

Tonyy_z

can you explain why you say the 350 tbi swirlport heads actually work well with tpi intake?

Fast355

iTrader: (2)

Has to do with powerband and air flow through both being fairly matched. The TPI was designed to go on a 305 and the 305 heads really do not breathe any better than the swirl port heads. TBI heads offer 65cc combustion chambers compared to commonly available 76cc smog chambers The swirl port intake port offers very good torque production, similarly to a TBI. You can build a very torquey, fuel efficient, responsive engine that works well with an OD transmission and the stock highway gear ratios in these cars.

Tonyy_z

are there any other heads that would work or just the ones you stated above? If I found l98 heads would that be better ?

dmccain

iTrader: (2)

L98 heads are slightly better on intake, maybe not on exhaust but yes they are slightly better heads. A lil porting and the L05s would be good if you would be satisfied 250-270 hp range.
Would be feasable with a nice cam. TPI are designed for low end torque and so are the 193 heads on that L05.

Tonyy_z

thanks for the response . Yeah I think I might just go that route just try to port the 193 heads at home and small cam