Jim Gross

Ok I have a 1987 IROC-Z TPI engine...it has sat for years because of my health. My friend who is my mechanic has offered several times to swap the motor with 305 he built. I have always told him that I want to keep it original. The one he built he built for drag racing with stronger pistons, shaved heads, roller rockers and a bigger cam. He tells me that I can keep all the TPI and the only thing I would have to give up is the center bolt valve covers because of the roller rockers it needs taller valve covers and his are a polished aluminum. This engine has a nice lope to it! My question is...are there any unforeseen problems that would arise in making this swap work or could someone direct me to specific resources that would help us through the process? Thank you in advance for any guidance.

Tuned Performance

iTrader: (92)

Jim Gross

I'm sure he does...I will have to get a hold of him. Thank you for your response! Trying to call him now...

Jim Gross

Cam specs: 480 Lift Thanks...that is what he said...

Tuned Performance

iTrader: (92)

Jim Gross

Sorry...I'm not a mechanic...totally illiterate when it comes to engines, I asked him for specs and he shot back 480 lift and said it was the biggest cam that he could put in a stock motor so I have no other info...Thank you anyway!

GeneralDisorder

iTrader: (1)

Need to know the duration @ .050" spec on the camshaft. TPI really doesn't like anything over about 224 intake duration. Causes too much reversion into the intake tract and gives really poor airflow sensor readings confusing the computer. The total lift tells us nothing about the cam's behavior but the description of the idle loping makes me think it may be too much on the .050" duration. As a general rule you can't put really rowdy cams in engines that will be fuel injected. But with modern hydraulic roller camshafts you really don't need to trade that nasty idle lope for performance anymore. You can make GOBS of power with a tame idle and a big lift cam with the new hydraulic roller grinds.

Ask him for a part number of the cam he used for the build.

Also - it's not that big of a deal to change the cam if it's not going to work with TPI. Assuming it's a flat tappet engine - there are several good Summit brand cams that will work for around $100. It's not really a deal killer and wouldn't take more than a few hours to swap it out.

GD

Jim Gross

Thank you for this info. I am going to see him tomorrow and I will relay this info to him. I really appreciate the help. My gut told me that there could be issues although I have read in the past that people have put bigger cams in TPI's but I'm a computer guy...not a mechanic at all. Personally my desire is to rebuild or refresh mine although I love the sound of the lope and the fact that it puts out nearly 350hp I really don't need it...never going to race it and to much potential to get in trouble with the law. Back when I was driving it there was plenty of power for me as is...not modified...factory. Well if he can give me any more info I will post it tomorrow...thanks again!