What heads?
 

I keep looking for the correct dated heads for my 71 Nova, which according to Colvin's numbers book should be 3973487. The problem I'm having is the casting date of the engine is I 12 0 (Sept. 12, 1970) and the build date is 1202 (Dec.2). I believe the difference is the GM strike (Spet. 15, 1970 to Nov. 20, 1970) 1970 GM History. It is the numbers matching block. The car is a 12A date.

Should I go with a date close to the casting date or the build date?

And does anyone know when they started making the 487's and stopped the 186's? If the 186's were made in sept. of 70, would they be acceptable since I have such an early car.
There are a set of 487's on ebay right now with L2370 and L2870 dates but they are too late for my build date and car.


Thanks, Dan

Re: What heads?
 

Dan,

To be safe, keep the casting dates of the heads within
6-8 weeks of the assembly date of the engine.. No one
will give it another thought. https://www.yenko.net/ubbthreads/imag...mlins/wink.gif

The casting date of the block has no real relevance to that
of the other components so long as none of the dates are after
the assembly date of the engine. https://www.yenko.net/ubbthreads/imag...emlins/eek.gif