Head Shave amount??

[jd52cranbrook]

I did a search on this topic, and I found that 100/1000 would still be fine?

I spent yesterday afternoon at another club event talking with a engine builder, and some others on the topic of why my Edgy Head does not want to keep plugs, or even inserts within it's confines. Last week I had a plug shoot out from my head on the freeway, and it had a regular time sert in it. I was able to put a Big Sert in it's place and continue on. I do have about 30,000 miles on the head, and do not make a habit of pulling plugs. But the thread count on a aluminum block should be more I think than it is. Plus, after talking to few older fellows in the know, my problem could be it was never hardened after it was cast. I am following up on that end. Another item I learned is that these Edgy heads are no where near 9:1 compression.

But I have my original head I want to put back on for the time being, would not mind taking some off the bottom just for kicks.

So does 100 thou sound safe enough? From the search I did it would seem so.

[41/53dodges]

sounds good for a briggs. measure the depth of the valve wells in the head, subtract lift height of valves, and take off some for clearance, and there you have it.

[james curl]

At .100" you will probably have to relieve the head on the outside of the combustion chamber by tightening the radii between the vertical to horizontal transition. I had mine milled .100 and I clayed the chamber above the valves and the outside edges of the valves cut through the clay in that area. I took a round burr and cut the radii tighter in those areas. I have around 20,000 miles on the engine since rebuilding it including a trip from Texas to California and Bonneville before returning to Texas.

[jd52cranbrook]

Thanks a bunch.

[BeBop138]

JD, I took 65 thou on mine, plus 3 thou on the deck----I then I started to worry and took 50 thou fly cut on the head in the valve area--buk-buk:D

[Jerry Roberts]

At .100" you will probably have to relieve the head on the outside of the combustion chamber by tightening the radii between the vertical to horizontal transition. I had mine milled .100 and I clayed the chamber above the valves and the outside edges of the valves cut through the clay in that area. I took a round burr and cut the radii tighter in those areas. I have around 20,000 miles on the engine since rebuilding it including a trip from Texas to California and Bonneville before returning to Texas.

This is just a question , because I don't know . It sounds to me like you are talking about increasing the size of the combustion chamber . Doesn't this defeat the purpose of milling the head for greater compression ? If that is the case , why not mill the head only enough to be sure that it is flat .

[jd52cranbrook]

Your right Jerry, I think a cut to still leave good valve clearance would be a good move. A friend of mine also thought cutting the valve guides a bit shorter would help with flow. I may look into that next winter when it comes apart for new guides.

[Plymouthy Adams]

There is no good reason to max mill any head just for a performance gain on the old falthead, street driven there is no way you will totally use this miniscule "performance" increase and to sacrafice future cuts to keep a head serviceable well into the future..just not cost effective in my book..that is exactly why these margins to rebore and mill are built into an engine..to prolong its life over a long period of time..these flatheads have ability to go .050 and better beyond max bore for most late model blocks of today..

now if you building strickly a flat out salt lake racer..then mill, fly cut, relieve..bore et etc till your hearts content..