Milling Snyder 6.0 Head

Richard in Anaheim CA

Richard in Anaheim CA

Well-known member
Has anyone had any experience milling the Snyder 6.0 head for more compression?

How did you mill it and what would you guess the compression is?

Richard
Anaheim CA
 
Richard in Anaheim CA said:
Has anyone had any experience milling the Snyder 6.0 head for more compression?

How did you mill it and what would you guess the compression is?

Richard
Anaheim CA
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Since no one else has responded, I will say this. Yes, I resurface each 6:1 head I install, -but to your question, not to necessarily increase compression. I resurface them to obtain a better surface finish, and to ensure the deck is truly flat. As for compression, I can cc it for you but in all likelihood you would only see a marginal increase of probably less than 0:1.
 
Worth noting that, overall, milling heads to gain compression is a tradeoff at best. You get the compression, but at the cost of further shrouding the valves – which didn't have great flow to begin with. So performance at high RPMs will be reduced compared to a head that's been designed to have that CR from the beginning.
 
alexiskai said:
Worth noting that, overall, milling heads to gain compression is a tradeoff at best. You get the compression, but at the cost of further shrouding the valves – which didn't have great flow to begin with. So performance at high RPMs will be reduced compared to a head that's been designed to have that CR from the beginning.
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Colin, it has been my experience that the shrouding occurs on the backside of the valve from the seat up to the head, and not so much in the roof area. The chamber walls on the backside of the valve are pretty much vertical which likely won't cause much additional shrouding if the head is lowered. The biggest issue with milling the head too much is lowering the counterbore in the head where you get interference with piston protrusion. It is my opinion that instead of increasing the compression, that work spent on increasing air-flow efficiency will net a greater gain.
 
When I first bought my 5.5 Snyder Head, I installed it straight out of the box (after painting it). I ran it like that with no problems. When I had a new touring engine built and re-used that head, my engine builder said that he just routinely surfaces any head regardless. He did say that he only just skimmed mine as it was actually pretty close anyway.
 
Unfortunately my 5.5 was just the opposite. I had to mill, as I recall, 8 thou, to get it flat. About that same time(5 yrs ago?) there were reports of several “ out of the box” heads that weren’t flat.
 
Raising compression is only one piece of the puzzle..fuel,camshaft design, ignition upgrades..it takes a balance of all components to make good smooth efficient power..a modified flathead ford four cylinder engine geared correctly can compete in today's traffic..along with a tight chassis and 16" rubber ...even mechanical brakes do the trick if you set them up right..that was the goal of my build,to drive solo in CA boulevard and freeway traffic without being a menace..
 
My experience in milling a head for more compression is on a stock "low" head for a Model T. about 5/8 inch was removed. It worked great. I don't know what the resulting compression ratio was. So, has anyone milled a stock A head to gain compression ratio? I suspect the area above the piston would have to be relieved to clear the piston.

BTW, the milling on the T head went into the water jacket but it was blocked by the head gasket.


Just as important as the higher compression ratio is the combustion chamber design. Does the design promote turbulence? Does it relieve the valve area for better flow?
 
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I took my new 6:1 head (2019) to the local auto machine shop to check flatness and he said that it was surprisingly flat.
 
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