I just pick my motor up from the machine shop and notice that I could not install the coolant pipe in the rear of the heads so I took off one of the valve covers and notice that the casting number was 10128374 and not 10168448 could some one pls tell me what kind of head they put on my car. Because its not the one's that were on the motor before

 

its an aluminum lt1 head. not sure exactly what car or year they came on but i know that is one of the castings that can be cnc'd

 

That brings up a 92-up...350..........Gen.II LT1, 53cc, angle plug,aluminum, reverse flow cooling,175/68cc ports 101

 

should I keep those heads or try to get my heads back

 

No they are fine.

 

Is one better than the other

 

Was 10168448 actually cast in the heads you took in?

 

yes 10168448 was the casting number that I took in

 

Is this just the difference between the "early" and "late" LT1 aluminum heads?

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

 

I dont know.

 

A search shows that the "374" casting is the preferred head for really large porting.... check the AI website 200cc LT1 heads.

I think the "374" is the "early" head and the "448" is the later head. Don't confuse the part #'s with the casting numbers posted in the link above.

 

The crossover coolant tube was the same for all years lt1....

 

You'd only have a problem with the cross-over pipe if the heads were milled a lot, moving the holes closer together. Dosn't matter which part # you started with.

 

and if you do , just bend the tube slightly to get the holes lined up

 

Thank you guys for all your help. I was getting ready to do battle with the company who build the motor. Next time I will do the job myself