Please Help me Identify this Head on my Lt-1

[Christopher K.]

I have a '72 Lt-1 with a late June build. My right head numbers match fine - 3973487X, with a cast date of C 7 2.

The left head is a mystery. I've attached some pics. The numbers I can see on one side are 3 88 with K 14 3 below it (I think). On the other side is a large GM 2 . There is also a 2 1 between casting screws (maybe!).

I see no other "normal" numbers. Any help is greatly appreciated!
Chris

[Terry M.]

Re: Please Help me Identify this Head on my Lt-1

During judging we identify cylinder heads by the symbols cast into the ends of the head in part because we don't remove the rocker arm covers. Any chance you can get a picture of the end of this head?

If one were to believe those numbers were 86 -- it looks like they could be -- then maybe you have 3927186 cast in 1973 as a service replacement. The end symbol will tell.

[Christopher K.]

Re: Please Help me Identify this Head on my Lt-1

Thanks Terry,

Here's 2 pics of the symbol

[Joe L.]

Re: Please Help me Identify this Head on my Lt-1

Thanks Terry,

Here's 2 pics of the symbol

Christopher------


This is not a cylinder head ever originally used on a 1972 LT-1. The casting symbol is not that used for the GM #3973487X or the 3998916. It is, however, the casting symbol used for cylinder heads GM casting #333881 and 333882. I have a feeling that the "3 88" that is seen might be part of an incomplete casting number.

The 333881 and 333882 were 1974-75 cylinder heads. The casting date on this one being November, 1973 would be entirely consistent with these heads being 1974 model year heads. It's very likely that these heads were used for SERVICE of earlier applications like your 1972 LT-1.

So, given the date on them, I would say it's likely this head was installed on your car as a warranty or otherwise replacement of one of the original heads and, if so, probably sometime in early 1974.

[Christopher K.]

Re: Please Help me Identify this Head on my Lt-1

Thanks Joe,

As always, a very detailed and informative answer! I owned the car from 1984-2006, and recently bought it back. I decided to replace the valve cover gaskets and was really puzzled by those numbers.

Thanks very much for the explanation,
Chris

[Christopher K.]

Re: Please Help me Identify this Head on my Lt-1

Just have to ask....

Assuming the rest of my engine is original (and I believe it is), how big is the point deduction for this incorrect head?

I'd really hate to replace it, it's been running great for 37 years!

Thanks, Chris

[Joe L.]

Re: Please Help me Identify this Head on my Lt-1

Just have to ask....

Assuming the rest of my engine is original (and I believe it is), how big is the point deduction for this incorrect head?

I'd really hate to replace it, it's been running great for 37 years!

Thanks, Chris

Chris------

That I do not have an answer for. The casting symbol is, essentially, the only difference that can be seen in the judging process. Of course, that infers a non-original casting number. I would definitely not change the head just to correct this configurational difference.

[Terry M.]

Re: Please Help me Identify this Head on my Lt-1

Just have to ask....

Assuming the rest of my engine is original (and I believe it is), how big is the point deduction for this incorrect head?

I'd really hate to replace it, it's been running great for 37 years!

Thanks, Chris

Chris,

The judging sheets are available on line:

https://www.ncrs.org/membership/scoresheets.html

For 1973 to 77 the Mechanical sheet shows 50 originality points for Cylinder heads and 0 condition points. So I would say 1/2 of 50 points = 25 points for one head that deviates from Typical Factory Production. That is out of 4500 + a few points or about 0.5%

[Patrick H.]

Re: Please Help me Identify this Head on my Lt-1

Chris,

The judging sheets are available on line:

https://www.ncrs.org/membership/scoresheets.html

For 1973 to 77 the Mechanical sheet shows 50 originality points for Cylinder heads and 0 condition points. So I would say 1/2 of 50 points = 25 points for one head that deviates from Typical Factory Production. That is out of 4500 + a few points or about 0.5%

However, since his car is a 72 LT-1 he should probably look at the 70-72 sheets. Thankfully, the points allocated are the same so it's still probably 25 points.

Patrick

[Michael F.]

Re: Please Help me Identify this Head on my Lt-1

I would leave as is and search for another correct head dated near other one and then change when something else dictated head removal, like engine or head refresh.

[Christopher K.]

Re: Please Help me Identify this Head on my Lt-1

Thanks, everyone for the advice.
Chris

[Terry M.]

Re: Please Help me Identify this Head on my Lt-1

However, since his car is a 72 LT-1 he should probably look at the 70-72 sheets. Thankfully, the points allocated are the same so it's still probably 25 points.

Patrick

Boy, did I miss that one. And he asked about LT1 besides. That 1973 date just sucked me in.