350nova72

I am rebuilding an 82 350 that has been rebuilt before and my heads have two different casting numbers, they are 462624 and 3973487 is it normal to have this or did someone switch a head. I know the engine ran before but what would happen if they were different heads with different size intake and exhaust. just need some help figuring out what is goin on??

aj_wicked13

462624.....75-86...350/400......76cc chamber, 1.72/1.5, 1.94/1.5 or 2.02/1.6 valves
3973487....71-72...350..........75cc chamber, 1.94/1.5 or 2.02/1.6 valves, was also used on '71 350/330hp LT1

So yes they are different the chamber is a 76cc vs a 75cc.... how much difference is this well not a whole lot but it will cause your compression ratios on each side of the engine to be different.

chevyguy99

hey check out this website www.gmpartscheaper.com

troutdog

I wouldn't use them tho you could have the 76cc shaved to get it closer to 75cc. It might have already been done this way. That is if the valve size is the same. If the valves are different I would match them up better.
All in all,,, you probably couldn't tell the difference driving it anyway,,, On a stock motor or slightly modified.
Good Luck