1937 21 stud head comparision

[fryguy]

Since I picked up a couple set of NORS 21 stud heads I wanted to compare them to a stock head I had laying around to see the differences. The first head is a stock 37 cast iron head. The only markings are the Ford script at the bottom of the head. In the center of the head, there is just the number 7. This head looks like its been machined but not sure if its from the factory or a previous owner.



The second head is a NORS casted in 1946. There is a casting date of 4-16-46. There is a part number as well, 77-6050a. There is no Ford Script at all on the head. The casting looks as is with no machining done to the head.




The chambers look identical on each head except for a thumb sized indent on the NORS head at the lip of the piston dome. It looks cast in as well. There is no indent on the stock head
This is the stock head with no ident. The dome area actually looks larger in surface are, almost looks to be 3/4 quarters of a complete circle




This is the NORS head that has the indent in the Dome area. The dome area actually looks a little smaller in surface area, not much maybe 10/15 %. Then there is the small thumb size indent. This looks to be design to route the compressed air more towards the spark(?)



I have another set of heads that are actually running on the motor, which are the English Pilot Heads the 77E series with the firing order cast into the head. I have not pulled them yet to compare the chamber against these two.

Just figured I post and get peoples take on the difference in the heads. Not sure if folks have more pics of other 21 stud heads that were available for these engines. I'd be curious to see the chamber on a stock aluminum 21 stud against these two

Fryguy

[28A]

I have a pair of 21 stud '37 heads that i believe are either replacement heads, or they are Ford Pilot heads. They have the firing order on them. Dunno the compression ratios, and never bothered to take any notice of the combustion chamber. I wonder if they are different to what you have.

I also have a pair of 21 stud, '37 heads that are Ford factory aluminium heads. I haven't bothered to check if they are different to the other heads. Maybe i might have a gander sometime..

[Ol' Ron]

Time to start measuring the volume of the chambers. I modified a set of 37 heads by angle milling them for AV8 Paul's 239 engine and I think I ended up with around 7.5 CR. I did have to remove some material fron the valve area for the L-100 cam

[BillyB]

Sponsored Links (Register now to hide all advertisements)

Here is a set of NOS English heads with a 20 thou cut. I was told they were WW2 surplus from Pilot Trucks. They originally looked like they were cut with a chainsaw they were so rough. Guess they had good gasket sealant back then!