Need help, Im trying to find out if aluminum heads came out on all 305 TPI motors in 91? Because mine did and I cant find out why it did.

 

I always thought they were iron. Maybe someone put vette heads on it.

Check the casting number.

 

I bought the car with 89,000 miles on it and I took it out with 152,000 thats when I noticed it had aluminum heads, I know the person that had it before me didnt do anything to the motor. He didnt even wash the car.

 

I opened my oil cap and looked in with a flashlight and I seen mine.

 

No 3rd gen had aluminum heads.

 

So, what if they came stock for some reason? I could tell that the owner before me didnt know about cars by the way he took care of it. I have the old motor in storage and I need to look at the numbers, so what should the number be for a stock 305 in 91 z28 and what would the numbers be on aluminum heads. by the way, thanks for all the help in here : )

 

the only small block chevy aluminum heads in use at that time was the 113 casting 58cc corvette head, (now ZZ4 head). i am personally currently in the process of porting a set and installing them on my 305. there were not for any reason aluminum heads from the factory on any 3rd gen car at all. a few months ago there was a guy on here that had a 91 or 92 Z28 with an aluminum headed corvette L98 that had been dealer installed, but that is a super rare case. there were never aluminum heads installed on a 305 so if yours really does have aluminum heads someone put them on, bottom line.

 

A stock '91 Z28 305 TPI casting number was '081'. The 350 was '083'. And the 305 TBI was '187'. All were iron heads.

They had to be put on by someone. You stated that the previous owner new nothing about cars. I think we can also assume he know nothing about maintainance and care. So maybe he did not care for the vehicle and and killed the engine and on the rebuild he put on aluminum heads without realizing what they were.

It's possible.