Block -439 or -321 for Feb 1968 build?

[Gary K.]

From researching the archives I see that block 3935439 is the main production block for '68, that 3916321 stopped production in January 1968. My trim tag date is C16, the question is which block (or either?) is most appropriate for my car? This is a driver, but as I set up searches on Internet and look around to hopefully stumble upon the right block for sale I would like to know if one casting date is better than the other.

Question 2: My original tachometer yellow-lines at 6400rpm, redline at 6500rpm which somewhere I saw indicates L-71 which I would like to confirm with knowledgable NCRS members. I have other evidence pointing to an original L-71 in this car but still would like opinions. Thank You!

[Jack C.]

Re: Block -439 or -321 for Feb 1968 build?

Gary, my (F22) January 22 built has the original 3916321 block. I do think you are correct on the tach. Redline on a 435 hsp car starts at 6500. My L68 starts at 5600.

[John C.]

Re: Block -439 or -321 for Feb 1968 build?

Gary

I would just look for a 4 bolt block with the correct date code for your car. If it is a 3935439 or 3916321 so be it. If the 3935439 wasn't in production yet, you won't find one with the date you need.

On a 68 435 hp car the red line begins at 6500. See the attached picture.

John

[Gary K.]

Re: Block -439 or -321 for Feb 1968 build?

Good advice gentlemen, thank you, I think the tach is the confirmation that I needed for my restoration moving forward with an L71 project. As a driver car I think it's not critical to have everything 100% but if I stumble across the right block - why not.

[Dale C.]

Re: Block -439 or -321 for Feb 1968 build?

Gary

I think my Jan 11 cast BB may have been at or near the end of the production of the 6321 and it made it through the Vette assembly process with a March 8 (H08) trim tag and production date of March 12. Don't foreget that that C (Oct) and G (Feb) are often mixed up on the tags.

Dale