Milling a B-3 head

[Doug Brown]

How much can you safely mill off of a B-3 head for a compression increase?

How much of a compression increase will occur with a .020", .030" and .040" cut?

Getting ready to take things to the machine shop!

[ToSloTrk]

I don’t know exactly but I’ve personally had .040 milled off and it worked great.


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[Doug Brown]

OK, thought I could get away with .040" off the head. Glad to hear from someone who has done it.

Did you notice any horsepower gain from the milled head/higher compression?

[ToSloTrk]

I also did a home shop port job and added a FMS cam at the same time.
I was happy with the combination as it had more power and would get high 40’s to low 50’s for mpg.
I’d do that combo again rather than the B6 I currently have.


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[theastronaut]

In case anyone is searching in the future, I took .100" off a scrap head and didn't run into any water ports. That takes the compression ratio up to roughly 12.8:1 on a stock bore b3.

[1990new]

In case anyone is searching in the future, I took .100" off a scrap head and didn't run into any water ports. That takes the compression ratio up to roughly 12.8:1 on a stock bore b3.

If you have not installed that head on an engine can you do some measurements of the thickness from the valve cover edge to the block mounting edge. I had a head rebuilt about 3 years ago that is sitting on the shelf in the garage and I'm not sure how much they took off of it. And do you know the standard thickness of the new head?