possible fake 391 heads?

[Jacob A.]

[Mark #28455]

obvious clues

The heads in question must be closed chamber rectangle port heads. Although it is possible someone may have used a 1965 or 66 vintage head as a donor, it's not that likely given they cost big $$$ too. More likely would be an 840 head from 68-69 or a 1970 and newer 291(?) head. The 1968 and newer heads will have a 1/2" pipe thread hole over/beside one of the exhaust ports for the temp sender - the 1967 heads should not have this hole and boss. The 1970 and newer heads will have taper seat 5/8" hex spark plug hole machining whereas the 1969 and earlier use a 13/16" gasketed seat plug.

Good luck,
Mark

[Jacob A.]

In 1966, Were Heads ever cast on a SUNDAY?

The casting date on the heads is a Sunday!

I forgot to ad this part of his email....

"I forgot to mention that L 18 6 was a Sunday, which is just another oddity that I cannot find on any head casting dates regardless of the number!

I did not realize this until after the purchase."

thanks,
Jacob
#40987

[Joel Falk]

Re: In 1966, Were Heads ever cast on a SUNDAY?

Here are Jacobs pictures

Front

Back

Top

Top #2

Bottom

Bottom #2

Date

[Jacob A.]

Re: In 1966, Were Heads ever cast on a SUNDAY?

Thanks Joel!

Now lets hear what people think.

again thanks,
Jacob Angel
#40987

[William C.]

Re: In 1966, Were Heads ever cast on a SUNDAY?

Yes. on occasion the heads were cast on a sunday, I think you are missing the larger question here, regarding the size of the sparkplug holes and the presence or lack of the boss used on very late '67 and all later heads. If those are looking ok, the heads are very much more likely to be good.

[Jacob A.]

Re: In 1966, Were Heads ever cast on a SUNDAY?

Thanks very Much Bill, I didn't miss the bigger picture, but thanks for bringing it back to my attention.

These are not my heads, hence I don't have them to compare or take measurements of the spark plug holes. I don't know about the lack of the boss. I am waiting on my buddy who owns the heads to get home and grab his email with a link to this thread... He will answer our questions.

Thanks,
Jacob

[William C.]

Re: In 1966, Were Heads ever cast on a SUNDAY?

The Boss is a real killer, the numbers in the casting dates were variable as a new impression was made for each pour. There is a lot on information on the casting process in the archives, and one of our members from the Saginaw area has samples taken from when he worked at the Saginaw grey iron foundry. The boss would be hard to hide, and did not show up until late in the 67 model year. As stated previously, starting in '68, the heads were all drilled and tapped on that boss, with a temp sensor going in one side of the engine and a plug in the threaded hole on the other side. The boss has been seen as early as May of '67 I believe, and it may be mentioned in the Judging Guide.

[Jacob A.]

Re: In 1966, Were Heads ever cast on a SUNDAY?

I am pretty sure that the boss is not there, as per conversation I had with my friend. He will tell me for sure tonight.

Thanks again.
Jacob Angel
# 40987

[Jacob A.]