C2 Flint vs Tonowanda Small Block Heads

[Bill L.]

Hi:

There are numerous posts on this board about Flint vs. Tonowanda heads on C2 small block equipped cars. The judging manual(s) (At least the '67 manual) points out the difference; Tonowanda = rough surface on the double hump area and Flint = smooth surface on the double hump area.

My question:

Can anyone state or cite the definitive documentation that proves these cars should only have so called 'Flint heads"??? (i.e. smooth double hump surfaces---)


Thanks
Bill

[Patrick B.]

Re: C2 Flint vs Tonowanda Small Block Heads

Are you suggesting that some of the heads machined at the Flint plant from Flint castings did not have the double humps machined smooth, or are you suggesting that some Flint engines were assembled with heads cast and machined in Tonawanda?

[Bill L.]

Re: C2 Flint vs Tonowanda Small Block Heads

Are you suggesting that some of the heads machined at the Flint plant from Flint castings did not have the double humps machined smooth, or are you suggesting that some Flint engines were assembled with heads cast and machined in Tonawanda?

Good question Patrick:

I am questioning the claim in the judging manual that "ALL" Flint small blocks had smooth surfaces on the head double hump areas.

Bottom line: Where is the documentation to support this claim????

Just to really throw a curve ball into the mix: My small block 67 300 HP car with original motor has a driver side head with both the front and back double hump areas that are smooth(so Flint??? Right???)...... HOWEVER---the passenger side has a rough surface on the forward double hump and a smooth surface on the double hump at the rear of the head =======(So this one came from what plant???)

Thanks!!
Bill

[Patrick H.]

Re: C2 Flint vs Tonowanda Small Block Heads

(So this one came from what plant???)

Thanks!!
Bill

You could always remove the valve cover and take a peek...
I believe that the date code format would be different.

[Patrick B.]

Re: C2 Flint vs Tonowanda Small Block Heads

If the head was cast at Tonawanda, the casting date would use two digits for the year rather than just one for Flint (7 for Flint, 67 for Tonawanda). Also, there is usually a "T" cast somewhere on a Tonawanda casting. Check the casting date of your odd head.

[Bill L.]

Re: C2 Flint vs Tonowanda Small Block Heads

You could always remove the valve cover and take a peek...
I believe that the date code format would be different.

Yep:

I have photos (Changed out the gaskets to stop an oil leak and took these photos in the process for general documentation) ---

Top with both double humps smooth (J256)
===and bottom with both rough and smooth double hump surfaces (K226)



I don't see any difference --- the car was built on December 5th 1966 by the way.

Thanks!!
Bill

[Bill L.]

Re: C2 Flint vs Tonowanda Small Block Heads

Thanks Pat:

See my previous post ====with the photos of the dates ====

Both heads have a single digit date code so Flint then=====

Still wondering where the information in the Jugding Manual came from with regard to the surfaces.

If your guidance is right about the dates (and I assume it is) then the right side head has BOTH types of surface on the double humps....

Thanks for providing this info...

Regards
Bill

[Marco H.]

Re: C2 Flint vs Tonowanda Small Block Heads

Bill,
The information collected and used in the Judging Guides typically comes from many observed original examples and possibly manufacturing blue prints from Flint and/or Tonawanda. Based on the date formats, both your heads were cast at Flint, and one missed a step in the machining process. That doesn't make it wrong, it just makes it unusual. I would leave it alone. As we may pay more attention to such details, more examples may show up.

What may do not understand; writing a Judging Guide requires very often to put "gray areas" into "black and white". The information included in there is what most observe as typical at the point of print. New data is continuously collected and accumulated to be included in future revisions.
Nick Culcowski, as well as other Team Leaders are doing a fantastic job working with many hands-on individuals to keep the JG to the highest standard.
Marco

[Mike M.]

Re: C2 Flint vs Tonowanda Small Block Heads

the fact that one of the two ends of your head was broached means, to me, that the head is definitely a flint cast product. i've seen flint heads with very light removal of the sand casting camel hump area on ore end of the head and deep, significant broaching removal of the camel area on the other end of said head. all tonowanda heads i've owned had significant sand cast texture on both ends of said head. mike

[Joe L.]

Re: C2 Flint vs Tonowanda Small Block Heads

Yep:

I have photos (Changed out the gaskets to stop an oil leak and took these photos in the process for general documentation) ---

Top with both double humps smooth (J256)
===and bottom with both rough and smooth double hump surfaces (K226)



I don't see any difference --- the car was built on December 5th 1966 by the way.

Thanks!!
Bill

Bill-------


One non-related thing I note is that it appears that this engine has had the head bolts replaced. The head bolt I see is a flanged head bolt with a different style headmarking than normally seen on original small block head bolts. Functionally, this is a good thing; GM should have used flanged head bolts for small blocks but they did not. It's just not original. Not that it should matter; no one will see them, anyway.

[Bill L.]

Re: C2 Flint vs Tonowanda Small Block Heads

Bill,
The information collected and used in the Judging Guides typically comes from many observed original examples and possibly manufacturing blue prints from Flint and/or Tonawanda. Based on the date formats, both your heads were cast at Flint, and one missed a step in the machining process. That doesn't make it wrong, it just makes it unusual. I would leave it alone. As we may pay more attention to such details, more examples may show up.

What may do not understand; writing a Judging Guide requires very often to put "gray areas" into "black and white". The information included in there is what most observe as typical at the point of print. New data is continuously collected and accumulated to be included in future revisions.
Nick Culcowski, as well as other Team Leaders are doing a fantastic job working with many hands-on individuals to keep the JG to the highest standard.
Marco

Thanks Marco:

I fully understand the process of writing the manuals and I have great respect and gratitude for those that write them. I understand the "gray areas" as well. This subject, in my opinion, is one of them. I can certainly understand and it is logical that Flint sourced engines would all have similar parts. Again, that is logical and common sense would dictate it to be true. However, I still struggle with the "observation" issue. Clearly, we have NOT seen all the cars but that is another discussion and a statistical one at that. In the spirit of "Not TYPICAL factory production" it would also seem logical that a given engine could have two heads from the two different plants. How would that happen? Possibly an on-line engine repair in St. Louis??? (I assume that was done?), maybe an issue with parts in stock at one engine plant or the other???? There is also the possibility of service replacement by a dealer using a "Tonowanda" head on a Flint engine.....altogether a different approach and discussion for that one .....

Bottom line my point here is that (again my opinion) Different heads showing up on an engine is certainly a "possibility"..... it may not be "Typical" but it is certainly "Possible" ---- My concern in this instance is this is stated as an "absolute" in the manual. I am not making any changes to my car.... I simply offered it as an example --- one pretty clear aberration from the stated absolute.

Thanks for chipping in on this one---

Regards
Bill

[Joe L.]

Re: C2 Flint vs Tonowanda Small Block Heads

Thanks Marco:

I fully understand the process of writing the manuals and I have great respect and gratitude for those that write them. I understand the "gray areas" as well. This subject, in my opinion, is one of them. I can certainly understand and it is logical that Flint sourced engines would all have similar parts. Again, that is logical and common sense would dictate it to be true. However, I still struggle with the "observation" issue. Clearly, we have NOT seen all the cars but that is another discussion and a statistical one at that. In the spirit of "Not TYPICAL factory production" it would also seem logical that a given engine could have two heads from the two different plants. How would that happen? Possibly an on-line engine repair in St. Louis??? (I assume that was done?), maybe an issue with parts in stock at one engine plant or the other???? There is also the possibility of service replacement by a dealer using a "Tonowanda" head on a Flint engine.....altogether a different approach and discussion for that one .....

Bottom line my point here is that (again my opinion) Different heads showing up on an engine is certainly a "possibility"..... it may not be "Typical" but it is certainly "Possible" ---- My concern in this instance is this is stated as an "absolute" in the manual. I am not making any changes to my car.... I simply offered it as an example --- one pretty clear aberration from the stated absolute.

Thanks for chipping in on this one---

Regards
Bill

Bill------

I don't think this is a case, at all, of a Tonawanda head being installed on a Flint small block. I think that what you're seeing here is just a Flint machining anomaly. That could happen for a variety of reasons but most likely originates from an anomaly in the casting. In the latter case, the anomaly was not serious enough to cause the head to be scrapped but did cause an "irregularity" in the external appearance of the head. I'm confident that Flint inspectors were not too concerned about that sort of thing. It could be, though, that when this head was machined it caused some "cuss words" from the machine operator.

[Cecil L.]

Re: C2 Flint vs Tonowanda Small Block Heads

Single digit casting year is not the absolute rule here.
There was a period when Tonowanda cast heads and some blocks with a single digit year.
I have a 462 casting with single digit year and a T stamped, not cast just below the casting number. They also have a two digit number cast near the first spark plug hole.
I also had a 68 Tonowanda 327 block with a single digit year casting date.

See discussion a pics here:

Machined vs NON-machined double humb symbol on 461 heads

[Bill L.]

Re: C2 Flint vs Tonowanda Small Block Heads

Joe:

Yes the non-smooth end is rough and has some significant machine marks on it -- (the irregularity).

See below - a couple of ridge / machine marks on the face of the head are clearly visible:



I don't see this as an issue ---both heads are Flint (on my car) --- so good to go --- no changes will be made.

I am still thinking it would have been possible for a car to have one of both types of head for any number of reasons.

Thanks!!
Bill

[David L.]

Re: C2 Flint vs Tonowanda Small Block Heads

Most of the Tonowanda cylinder heads that I have seen in the past 35 years have the very common 2-digit casting year, however, I once had a pair of 3782461 cylinder heads dated "H205" and "H35" (August 20, 1965 and August 3, 1965) that had a large "T" casting. When I bought my "early" 1963 Corvette in the late 1980's it had a 1967 Chevrolet 327 engine in it with 3890462 cylinder heads and "I86" casting dates (Sept. 8, 1966) along with the large "T".

Dave