Shave or not to shave?

Cadillac Bill

Cadillac Bill

Member
I have a 1926 T Speedster. Have some overheating. I ran the engine and in a few minutes (At the correct water level) I saw bubbles coming up in the radiator neck.

I pulled the head and the head gasket showed no issues. Before reinstalling, I decided to have the head shaved. I have flat top pistons.

I did a test on the head to see if it had been shaved beore. No stampings from a machine shop. I did a test to see the amount of space in the combustion chambers in the head. I have 275cc which indicated the head not been shaved before.

I think I can shave 35 Thousands and the valves should not hit it.

I have been told about diametric opinions ranging from much greater power, to none.

Suggestions?
 
J Franklin said:
Starting with around 20 HP you won't notice too much. I would just make sure it was a flat surface.
Click to expand...

Thank you for your response.

I have heard that 1926-27 Model T somehow it was about 4 to one compression ratio, less than than 4.5 in earlier models. I have heard that a shave of 1/8th maybe up to 1/25th inches. I could get up to about 5 or 5.5 to one.

I have heard that I take a lump of clay on the tops of some valves, torque the head down, rotate the engine and see how much extra clearance will clear as it is, but still have a question that I could get the water jacket too thin?

Back to your question, about "a flat surface"?
 
High compression heads are available at most T parts suppliers. I was just saying shave to a flat surface for good gasket sealing.
 
You can feel the difference with .125 off the head. You need to find someone with an
old rotary broach type of machine, the new machines give a much finer surface
but they can't remove a whole lot of metal in one pass.
My old rotary broach can take off as much as .050 in one pass.
 
Dodge said:
You can feel the difference with .125 off the head. You need to find someone with an
old rotary broach type of machine, the new machines give a much finer surface
but they can't remove a whole lot of metal in one pass.
My old rotary broach can take off as much as .050 in one pass.
Click to expand...

I have heard that .25" Could be shaved. A local machine shop tells me they can do at .125, or even at ,25 for $100.
 
Spend the extra and get a real higher compression head from Snyder’s or one of those places.
 
I guess it was when i was young and dumb I, took my head to the local parts jobber with a machine shop. I spoke with the machinist to say I wanted it cut. He looked it over and turned to his assistant and said, "You can really cut a lot off of these with no problem".

Upon my return I was informed that he noticed a lot of rust flakes which he hosed out with water and air. If told me how much he removed, my brain was busy processing the cooling issues.

Bottom line it performed much better. Hills became less of a problem.
 
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