I have a stock LT1 in my 95 camaro what casting numbers do I probably have.
I am looking for a set to get ported what cast# do I want?

 

This thread covers the two variations on the LT1 castings:

http://web.camaross.com/forums/showthread.php?t=427346

 

it says that 94 have the good heads but not which ones, then it also says that 96-97 have 561 and they are bad for porting. I am guessing I have either 374 or 643 castings then.
Also are the 643's best for porting then?

 

My 1995 has the 643 castings.
People tend to deal in absolutes. I am sure there are plenty of 561 heads that have been ported and I would not consider them "bad" for such. The earlier casting just have a little more meat on them for porting ease (as others have said).

 

thank you for clearing that up for me both of you guys

 

My '96 has the 643 cast heads .....

Thomas.

 

I've heard that too! My 96 had the 561s. I've got a feeling the early run of 96 LT1s got the 643s until they ran out and the later got the 561.

 

FWIW, the mfg date on mine is 8/95 out of Canada

 

I have no idea on mine... sold it. My 97 has 561s too.

 

so if my build date was 8/95 then I have 643 which are good then right?

 

My car is a '96 with a mfg date of 8/95. Your mfg date will be earlier if you have a '95. Easiest way to check is to take the driver's side valve cover off and look at the casting number in the head.

Thomas.

 

...and where else would it have been from? All of our cars came from the same plant.