Heads

[Brad H.]

Was given some heads and valve covers to match, was told it was big block vette, who can tell me what year etc? Pass 336781 GM 9T and 10T L10-73 781 valve side Thanks Brad.

[Joe C.]

Re: Heads

336781 454 73-85 Oval Port

Cast date December 10, 1973

[Brad H.]

Re: Heads

Thanks Joe, what kind of value are these is I may ask? Brad

[Clem Z.]

Re: Heads

they are one of the best flowing stock oval port heads you can find. these are great heads for a street driven BBC engine.

[Joe C.]

Re: Heads

Thanks Joe, what kind of value are these is I may ask? Brad

Brad,

Sorry, but I can't give much help for their value.
They are "open chambered" heads, which will flow better than "closed chamber" heads because the valves are less "shrouded". The downside, though, is that they will develop less compression in an engine than an identically configured engine using "closed chamber" heads. That is actually beneficial if you use a modern camshaft with low overlap, fast valve acceleration, high lift, and long durations. These modern camshafts are designed to deliver excellent and broad torque bandwidth using lowered (STATIC) compression. The price one pays for this, is the requirement to use a more aggressive valve spring that that needed for the "classic" high performance camshafts.
My recommendation is to Google :"Chevy 336781 Heads" and see what comes back. Follow listings in e-bay to get an idea of pricing. Check selling prices in as many other listings that you can find, such as salvage yards, Chevy parts retailers, etc.. It won't take long to determine their fair value.
BBC heads are generally priced 50-100% higher than SBC heads, and, if they are an efficient replacement head, I wouldn't be surprised if they wouldn't fetch as much as $750.00/pair.
Good luck.

Joe

[Jack H.]

Re: Heads

While that cast number may fit/work with late Corvette 454 engines, it was NOT a casting that factory original... The 6-digit casting numbers for BB 454 Corvette heads that were used are defined by NCRS judging literature as:

353015, 73-74
336789, 74

If you want to know value, go do a Google search and see what you come up with... In general, oval port heads are pretty cheap, it's the HP square/rectangualr port heads that fetch decent money. I just saw a single 336781 sitting without much action on eBay at $10...

Perhaps you should question the fella you got this stuff from on why he believes it's a 'Corvette' cylinder head!

[Joe L.]

Re: Heads

While that cast number may fit/work with late Corvette 454 engines, it was NOT a casting that factory original... The 6-digit casting numbers for BB 454 Corvette heads that were used are defined by NCRS judging literature as:

353015, 73-74
336789, 74

If you want to know value, go do a Google search and see what you come up with... In general, oval port heads are pretty cheap, it's the HP square/rectangualr port heads that fetch decent money. I just saw a single 336781 sitting without much action on eBay at $10...

Perhaps you should question the fella you got this stuff from on why he believes it's a 'Corvette' cylinder head!

Jack-----


The GM #336781 are Corvette heads. They were used for 1974 Corvette with LS-4 as well as other 1974 Chevrolet big block applications.

I can't find any record of 336789.

[Jack H.]

Re: Heads

Thanks for the correction, Joe!!! I flipped through my NCRS, pocket, Corvette Spec Guide for the reply. Problem: I was quoting from the intake manifold page, one flip page past cylinder heads...

Appreciate the correcting post you made!