i am new to all of this and would like some help if someone is willing. my first project car is an 85 iroc camaro with a 305 tpi. when i bought it i was told the engine had never been torn into, which as i figured, was false. somebody swapped the heads for 87 or newer heads. can anyone explain to me why someone would do this? do the newer heads create more power or flow more air? they drilled the intake to fit the newer heads bolt angle and filled the holes with what looked like silicone. is this a problem? should i try to find correct year heads or just put the engine back together the same way they did? any help would be greatly appreciated.

 

Welcome aboard thirdgen.org.

It would help to know what castings these heads are. The number is under the valve cover between a couple of rockers. Knowing that would be the only way to really answer your question.

Generally speaking, the heads that came on the engine were 416's (the last three digits of the casting number are all you need to identify heads). If '87-later 305 TPI heads were put on, they would be 081's, which are identical to 416's except for the intake mount bolt angle you noted, and the centerbolt valve covers. However, '88-up 305's with TBI had "swirlport" heads - not a killer necessarily on a stock TPI engine, but if you want to go beyond stock, they are lacking.

A few years ago I bought an '87 LB9 complete engine, supposedly stock. As I investigated it, I found out it had one 081 head and one swirlport head, was bored 0.040"-over, and had dished pistons. It had obviously been rebuilt, I suspect as a dealer warranty. Complete screw-up of a job. Also found out the block was cracked in the lifter valley, so that engine never saw another minute of run time (still running the roller lifters I harvested from it, though).

Anyway, you never know what you have until you tear into it.

 

Have you taken the valve covers off yet?

Post the casting number from the heads (look at both to see if they match) and we will go from there.

 

the car is unfortunately covered in about 4 inches of snow. i will post the casting numbers hopefully tomorrow.

 

the casting number on the drivers side head is 14102193 which, from the help of google which led me to another thread on this site, told me they are off of a 350 tbi and pretty much crap. is this true?

 

They were not designed as a performance head. They were designed as a low end torque head.

That doesn't make them junk, it just means they run out of breath at 4000 or so RPM.

I would run them as is until I wanted to build a new motor.

They might actually work well with the TPI since it's a low end torque building induction system.

 

wont i run into problems with 350 heads on a 305 though? based on what i have read the compression ratio is lowered due to the larger dome size. i have also read that there are problems with the combustion chamber because the 350 heads are too large for the small bore of the 305. i really appreciate the help and i apolagize for being a pest i just feel it is better to do things right than to rig the vehicle.

 

found out why there are 350 heads on the car.. turns out someone at some point dropped a 350 in the car. not that im complaining but its kind of interesting for a vehicle that has never had the engine torn into.

 

You're still running the TPI, right?

 

definitely. i thought about going to a carb a while ago but i already have all the parts for the tpi. so now all i have to do is finish cleaning all the engine parts i have removed from the car and put it back together just about in time for all the salt to clear off the roads and drive it. plus in stock form, which i assume the engine is, tpi makes more power than carbed which is a major perk to a 20 year old.