427 head ID and general L71 advice please

[Greg L.]

I'm probably going to go and check out a 68 L71 car in a week or so and was wondering if there is any way to do a positive ID on the heads to be sure that they are correct without pulling the valve covers?

Also what would have been a required option with the L71? I think TI was required but was anything else required other than the standard 427 items like rear sway bar and different side yokes?

Thanks again.

Greg Linton
#45455

[Joe L.]

Re: 427 head ID and general L71 advice please

Greg-----

There's no way to positively ID the heads without removing the valve covers.

L-71 required K-66. Rear sway bar and HD-type stub axles were supplied with all big block engines and no small block engines.

[Joel Falk]

Re: 427 head ID and general L71 advice please

Greg,

Why do you suspect there is a problem with the heads? I'm not a '68 guy--wouldn't this car have '840 heads?

[Greg L.]

Re: 427 head ID and general L71 advice please

Joel- I'm just paranoid as heck about any 427 car these days because of what I've read about all the fakes out there. Maybe it's the aircraft mechanic in me that want's to eliminate any possibility of and incident such as buying a car that is missrepresented...

My head question came about because I remembered reading some place that you can install a rectangle port intake onto a oval port head. So in theory I suppose that it's possible to have L36/L68 heads(or any oval port head for that matter) on a L71 and not know it unless the intake or valve cover is removed. I just wanted to see if there was an easy way to check this possibility out without pulling a valve cover.

[Wayne M.]

Casting symbol on end of "840" heads

Greg -- do you have A.Colvin's book ('65-69 Chev by the numbers) ? pages 88 and 100.

Square port heads (391 and 840) have a hump casting symbol at the casting flash line (may only be on one end of the head). Also, the 840 will have the temperature sending element boss drilled and tapped (391 has boss w/o drill & tap). Oval ports (390, 215) do not have the symbol.

Colvin also says 840 differs from 391 in that "two accessory bolt holes are added to the end of the head". Can't give more details as I don't have either head.

Hope this helps.

[Joe L.]

Re: Casting symbol on end of "840" heads

Wayne----

In this case, I don't think that the issue will be over whether the heads are '391' or '840'. Besides, if the car had '391' heads, although incorrect, they'd be worth more than the '840'. They could be removed, sold, and correct heads acquired with, most likely, "money-to-spare".

Much more likely, if the heads are incorrect, is that they would be later GM SERVICE heads. Outwardly, these heads are identical to the '840' (with drilled and tapped fitting for temp sender as all 1968 '840' heads had).

[Mark #28455]

later heads have the same casting symbol

The 291 and the open chamber 188 heads share the same casting symbol but use the 5/8" taper seat (peanut) spark plugs. The small port heads from about 1969 on have a small rectangle casting mark about 1/4" x 3/4". The earlier small port heads do not, but they also lack the temp sending cast in boss.

Mark