3731762 heads

[Robert P.]

I have two sets of 3731762 heads. Both have proper part #s and are within two weeks of casting dates ( G-6-6 and G-20-6) but one set has the two towers on both ends of the head and the other only has them on one end. Can anyone tell me why?

[Edward M.]

Re: 3731762 heads

Pictures would help. Only thought that comes to mind is that one end was machined off. Is the casting raw or machined where the head symbol should be?

[Robert P.]

Re: 3731762 heads

Pictures would help. Only thought that comes to mind is that one end was machined off. Is the casting raw or machined where the head symbol should be?

Thanks for the reply. Took some pictures and can't seem to attach them. But I wire brushed the ends and it appears that the towers have been ground off one end. Don't know why. Ends are machined, not raw. I also thought that the single digit year suffix (G-9-6) denoted a correct Flint casting. True? Let me know if pictures came through.

[Edward M.]

Re: 3731762 heads

Robert;

I did not get any pictures, but I think you found the answer. Casting symbols have been machined off for some reason. Who knows why?

With enough work, a good welder could restore the casting symbols.
I have seen it done, but it really does take someone who understands
welding cast iron.

These heads are probably worth the effort, given the value.

Yes, single digit year in date code indicates Flint casting.

[Robert P.]

Re: 3731762 heads

Thanks. I appreciated your input. Going to sell this pair and wanted to make sure I had proper info.

[Terry M.]

Re: 3731762 heads

Working from memory, but I remember a thread on this board a week or two ago on the subject of cylinder heads, and the single digit year date was on a head casting with a T cast into it. That T was depressed and kind of faint, but showed up in a photo. I don't recall the year of that casting or the number, but what I took away from that thread is that the single digit year date does NOT necessarily exclude a Tonawanda cylinder head casting.

If I had a dog in this race I would be searching the threads from the last month, but I don't.

[Joe L.]

Re: 3731762 heads

All------


Not all Tonawanda castings use a 2 digit year code. This is is a "myth" that some folks regard as a "hard-and-fast" rule. Of course, these heads could still be Saginaw castings. However, if there is a "T" seen anywhere on the castings, then they are, for sure, Tonawanda-cast.

[Edward M.]

Re: 3731762 heads

All------


Not all Tonawanda castings use a 2 digit year code. This is is a "myth" that some folks regard as a "hard-and-fast" rule. Of course, these heads could still be Saginaw castings. However, if there is a "T" seen anywhere on the castings, then they are, for sure, Tonawanda-cast.

Is the 'T' stamped (recessed) or cast (raised) in this situation.

Do you have a reference for the Tonowanda and single year digit information? This is the first time I have heard this.

[Edward M.]

Re: 3731762 heads

I think this is the thread that Terry is referring to:

https://www.forums.ncrs.org/showthre...highlight=head

There is a theory postulated (I like that word) that a head with a single digit year date code, but also having a 'T' stamped (recessed) into the casting means that the head is a Tonowanda casting.

This issue came up a while back about 762 heads with a 'T' stamped into the casting, and also having a single digit year code.

OK, here is what Alan Colvin says about these heads:

"This cylinder head was released late in the 1956 model year. It had the same small combustion chamber as the #3725306 head. It was identical with #3703523 except that the valve guide boss diameter has been increased. There was also a truck version of this cylinder head released, but it had a much larger combustion chamber and a large "T" in the middle of the rocker arm area. The truck #3731762 cylinder head "twin tower" external head marking is also slightly different from the passenger car cylinder head. The towers are taller and closer togerther (1959). This cylinder head was also used in early 1957 production."


Based on this info, I suspect that the 'T' represents Truck, and not Tonowanda. So, a single digit year code head, with a 'T' stamped into the casting, would be a Flint casting truck application.

I have seen Tonowanda castings (two digit year codes) with the 'T' stamped into the casting as well.

Thoughts?

[Cecil L.]

Re: 3731762 heads

I think this is the thread that Terry is referring to:

https://www.forums.ncrs.org/showthre...highlight=head

There is a theory postulated (I like that word) that a head with a single digit year date code, but also having a 'T' stamped (recessed) into the casting means that the head is a Tonowanda casting.

This issue came up a while back about 762 heads with a 'T' stamped into the casting, and also having a single digit year code.

OK, here is what Alan Colvin says about these heads:

"This cylinder head was released late in the 1956 model year. It had the same small combustion chamber as the #3725306 head. It was identical with #3703523 except that the valve guide boss diameter has been increased. There was also a truck version of this cylinder head released, but it had a much larger combustion chamber and a large "T" in the middle of the rocker arm area. The truck #3731762 cylinder head "twin tower" external head marking is also slightly different from the passenger car cylinder head. The towers are taller and closer togerther (1959). This cylinder head was also used in early 1957 production."


Based on this info, I suspect that the 'T' represents Truck, and not Tonowanda. So, a single digit year code head, with a 'T' stamped into the casting, would be a Flint casting truck application.

I have seen Tonowanda castings (two digit year codes) with the 'T' stamped into the casting as well.

Thoughts?

Ed,
The referenced thread was specifically 461 castings that Tom Parsons has and some similar 462 castings that I have. I posted some pretty clear pics showing the single digit year casting and both the stamped T (below the casting number) and Cast T between the valve springs. The other head I have is clearly a Tonawanda casting and has the stamped T but not the cast T.
https://www.forums.ncrs.org/showthre...=2123#poststop
I suspect the change to single digit year on Tonawanda castings came about the same time as W engine casting shifted to CFD and they changed from 2 digit year casting to Julian dates. That was in late 62. I don't have any examples of late 62 or 63 Tonawanda small block castings, but I do have a 68 T cast 327 with single digit year.

[Edward M.]

Re: 3731762 heads

Ed,
The referenced thread was specifically 461 castings that Tom Parsons has and some similar 462 castings that I have. I posted some pretty clear pics showing the single digit year casting and both the stamped T (below the casting number) and Cast T between the valve springs. The other head I have is clearly a Tonawanda casting and has the stamped T but not the cast T.
https://www.forums.ncrs.org/showthre...=2123#poststop
I suspect the change to single digit year on Tonawanda castings came about the same time as W engine casting shifted to CFD and they changed from 2 digit year casting to Julian dates. That was in late 62. I don't have any examples of late 62 or 63 Tonawanda small block castings, but I do have a 68 T cast 327 with single digit year.

Cecil;

I'm not sure I follow your thought process here. Let me try it this way, and tell me what you think might be wrong:

Single digit year code, no letter T = Flint passenger car application

Single digit year code, letter T = Flint truck application

Two digit year code, no letter T = Tonowanda pass car application

Two digit year code, letter T = Tonowanda truck application

One thing I have noticed is that the early castings seem to have the letter T stamped (recessed) into the casting. The later year casting seem to have the letter T cast (raised). Could Chevrolet have done both (recesed and cast)? Certainly, not that it makes a lot of sense.

I still go back to Colvin's statement the T represents a truck application. That sort of makes sense to me, if you are using the same casting. The truck application heads could have the combustion chamber machined differently (for larger chamber size).

And, of course, I don't see any of the above as a hard and fast rule. I just haven't seen anything yet that convinces me that the large T (cast or stamped) means Tonowanda, and not truck.

Please enlighten me.

Here is a couple of pics of a head I just pulled off of Ebay. 1962 two digit year code with a cast T. My guess is this is a Tonowanda truck application.

[Joe L.]

Re: 3731762 heads

I think this is the thread that Terry is referring to:

https://www.forums.ncrs.org/showthre...highlight=head

There is a theory postulated (I like that word) that a head with a single digit year date code, but also having a 'T' stamped (recessed) into the casting means that the head is a Tonowanda casting.

This issue came up a while back about 762 heads with a 'T' stamped into the casting, and also having a single digit year code.

OK, here is what Alan Colvin says about these heads:

"This cylinder head was released late in the 1956 model year. It had the same small combustion chamber as the #3725306 head. It was identical with #3703523 except that the valve guide boss diameter has been increased. There was also a truck version of this cylinder head released, but it had a much larger combustion chamber and a large "T" in the middle of the rocker arm area. The truck #3731762 cylinder head "twin tower" external head marking is also slightly different from the passenger car cylinder head. The towers are taller and closer togerther (1959). This cylinder head was also used in early 1957 production."


Based on this info, I suspect that the 'T' represents Truck, and not Tonowanda. So, a single digit year code head, with a 'T' stamped into the casting, would be a Flint casting truck application.

I have seen Tonowanda castings (two digit year codes) with the 'T' stamped into the casting as well.

Thoughts?

Ed------


I have never known a "T" on any casting to represent "truck". A "T" on cast or forged pieces virtually always, if not absolutely always, represents Tonawanda-----either the foundry for cast pieces or the forge for forged pieces.

If a truck application used a different casting from a car application then, in most cases, the casting number would be different. The different machining that a truck part versus a car part might subsequently undergo would generally not be reflected in a casting mark.

[Edward M.]

Re: 3731762 heads

Ed------


I have never known a "T" on any casting to represent "truck". A "T" on cast or forged pieces virtually always, if not absolutely always, represents Tonawanda-----either the foundry for cast pieces or the forge for forged pieces.

If a truck application used a different casting from a car application then, in most cases, the casting number would be different. The different machining that a truck part versus a car part might subsequently undergo would generally not be reflected in a casting mark.

OK, lets assume that is correct. How do you reconcile that with Colvin's statement (yes, he can be wrong)?

Is there an "absolute rule" that distinguishes between Flint and Tonowanda cylinder heads (i.e machined vs raw casting symbols)?

[Joe L.]

Re: 3731762 heads

Is the 'T' stamped (recessed) or cast (raised) in this situation.

Do you have a reference for the Tonowanda and single year digit information? This is the first time I have heard this.

Ed------


In all cases that I am aware of, the "T" for Tonawanda is seen as a RAISED character. However, it's very possible that some were inset. Either way, I believe it represents Tonawanda. Many truck parts were cast or forged at Tonawanda.

As far as the year date code, I used to believe that all Tonwanda castings used a 2 digit year code. Then, I learned from multiple sources that I was wrong. I just don't remember what the sources were. However, I do recall that enough proof was provided that I unequivocally accepted that I was wrong. If you have some information that proves I was originally correct, I'd love to hear of it.

[Edward M.]

Re: 3731762 heads

Ed------


In all cases that I am aware of, the "T" for Tonawanda is seen as a RAISED character. However, it's very possible that some were inset. Either way, I believe it represents Tonawanda. Many truck parts were cast or forged at Tonawanda.

As far as the year date code, I used to believe that all Tonwanda castings used a 2 digit year code. Then, I learned from multiple sources that I was wrong. I just don't remember what the sources were. However, I do recall that enough proof was provided that I unequivocally accepted that I was wrong. If you have some information that proves I was originally correct, I'd love to hear of it.

Joe;

I have no proof, other than Colvin's statement, which made sense to me at the time.

I can certainly see that the T could be Tonowanda, and the raw casting symbol cylinder heads with the single digit year code also seems to point that way.

I'll poke around some more with other references and see if I can get any further info on this.

Fascinating.

I learn so much from this site!