Shaving stock head

[Cool Hand Lurker]

Is it worth the effort to shave a stock head?
How much can safely be taken off and what would the ratio be then?
I have a spare head and a Bridgeport and I would like to experiment.

[Tom Wesenberg]

I don't know how much can safely be removed, but I'm sure the compression won't raise enough to make it worth the trouble.

[ctlikon0712]

Also make sure the head on the Bridgeport is totally true to the table and the Way's aren’t sloppy or when you make multiple passes on the head with your Schell mill or fly cutter you will get a mismatch.... Not sure if you knew that or not and i don't mean to insult you if you did, but I posted that just as much for the readers.

[James Rogers]

You can remove as much as .125 from a stock head without problems. The difference in removing stock from the stock head and the 5.5 Snyder head is the design of the combustion chamber.

[Cool Hand Lurker]

"Also make sure the head on the Bridgeport is totally true to the table....."
Yup, a friend has a machine shop where they make fixtures and jigs for other shops and he told me they tram the head before every work session. You never know who used the machine before and whether they hit something that tweaked the head, even just a little bit.
I am self-taught but I listen well when the experts speak.

Jim, I know the Snyder's and Brumfield's heads have specially designed combustion chambers that really make a difference, but I have the spare stock head already. If that doesn't work out I might be giving you a call for one of your heads.

[Terry, NJ]

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Yes Tram the head! Make sure the gibs are nice and snug. Tighten the knee and crossfeed after indicating the head. Make sure you have enough travel and if the machine is old and worn, watch for table tilt as one end of the table aquires excessive overhang as you crank it past the end of the head. Ithink when your done milling it, you'd better set up a big piece of glass as a lapping plate and lap it for a hour or so.
Terry

[azmodela]

It sounds like you and your buddy have way too much time and spare mill bits on your hands! There's really nothing to experiment with here, its been done thousands of times over the years.

That's why the old 'C' heads were used in favor of stock A heads before moving onto other high compression heads that were and still are produced. The 'C' heads started with a higher compression ratio and better chamber design than what's employed in stock A heads.

[hardtimes]

Originally Posted by Terry, NJ

Yes Tram the head! Make sure the gibs are nice and snug. Tighten the knee and crossfeed after indicating the head. Make sure you have enough travel and if the machine is old and worn, watch for table tilt as one end of the table aquires excessive overhang as you crank it past the end of the head. Ithink when your done milling it, you'd better set up a big piece of glass as a lapping plate and lap it for a hour or so.
Terry

Terry,
Could you say ...what grit(s) you use in your lapping work and how is paper held in place

[George Miller]

You can take 1/8 with out problems, but you are better of with a 5.5 head.
If you try to machine your head with carbide cutter you will have a small step from one cut to the next. You have tool pressure to deal with. Every thing that is made from metal gives, tools deflect when cutting. You will need to use a fly cutter or a cutter big enough to go across't the head. If you use a end mill made of high speed steel you will have better luck. But you will still have a small miss match.

[Kohnke Rebabbitting]

George is right, you have to cover the head in one pass, or it will be stepped!

[Richard/Ca]

If I had some stock heads how would one know if they have been shaved or not? If as James Rogers stated the most it should be cleaned up is .125. I really don't know a much about machine work. Richard/Ca

[Cool Hand Lurker]

"It sounds like you and your buddy have way too much time and spare mill bits on your hands! There's really nothing to experiment with here, its been done thousands of times over the years. "

Yup, you are right. No sense at all to get out in the shop and mill a stock head, even though that is how I really enjoy my retirement. Yup. Get a beer and watch that Housewives of New Jersey show on TV. Maybe get some shell peanuts to crack for my exercise. Get out the computer and order some new 5.5 head from some supplier, play a few hundred games of Solitaire before shutting it down.
Yup, makes more sense than getting out to the shop and doing something that has been done thousands of times already. What a waste that would be.
I guess I will go out to the shop one last time and clean up the Bridgeport, coat it with cosmoline, put a box of sawdust on it with a small electric light too, which will create a dry temperate storage environment. and cover it with shrink wrap. Have a beer, toast Mr. Bridgeport and toast the experiments of Edison and Ford, then go in to bed, turn out the light and dream of sheep, puppy dogs and stock options.

[Kurt in NJ]

I didn't know that it wouldn't work with a 4" cutter and multiple passes---6 cyl BMW, "lapped" with 600 paper to be pretty-, 4cyl Saab,the lines are optical, the line showing from the 2nd pass is almost optical(less than .0001), 3 passes on this head, started with a head warped .028 the long way, .008 the short way, removed .011 from the head after straightening ----A 6cyl Benz diesel is a pain, can only get the mill off the head at 1 end, takes 5 passes, havn't tried iron, have an old Van Norman grinder for that.

[Gravelroad]

Cool Hand Lurker, You sound just like me. I enjoy my retirement just like you, out in my shop on the mill, lathe and surface grinder, maybe welding some things together for no good reason. Just wasting my time. Keep on doing your thing. Just because it's been done a gajillion times by others doesn't mean it's not an experiment to you. Keep the machines humming. Happy milling.

[Terry, NJ]

The glass is a lapping plate. Plate glass is pretty flat. Use the coarse valve grinding compound. lay the glass on something as flat as can be found. Place the grit on the glass and spread it around lots of it. Lay the head gently on the grit and move it around in a figure eight motion. After about 10 minutes pick the head up and see any low spots. Put a litle Kero on the grit and lap it some more. It's a slow way to do it, grinding is probably faster (Although .100?) But carefully milling and then finishing up on a lapping plate should give you the desired result. I have "flattened" a lot of surfaces with this method. Notably oil pumps, one for the Ford 8N and my old obsolete oil burner. Good luck. Old granite tombstones would work well too!
Terry

Originally Posted by hardtimes

Terry,
Could you say ...what grit(s) you use in your lapping work and how is paper held in place

[just plain bill]

"shaving" heads
Gee, I read all of these remarks about the use of this tool and that one. I also read of some cutting materials being better than the other one. Some methods are better than others.
Well a few years back I purchased a cast iron Winfield head that, I discovered later, been welded across the water tube area on the top. This was to repair an exterior crack. Engine side looked okay but the head was warped .045. Not knowing I was doing it wrong I milled it with a 2" diameter indexable carbide end mill. Taking it off in light cuts, dry, I ended up with a flat surface, no measurable mismatch in tool mark patterns using a .0005 indicator.
Of course I had indicated the Bridgeport head in beforehand using the same .0005 indicator on the end of a 6" arm.

[hardtimes]

Terry,
Thanks ! kero(?) kerosene. I just knew that I should't have gotten rig of that big slab of granite! Hmm, glass would be 'ground' ruff too,eh?

[bbrocksr]

Originally Posted by Cool Hand Lurker

"It sounds like you and your buddy have way too much time and spare mill bits on your hands! There's really nothing to experiment with here, its been done thousands of times over the years. "

Yup, you are right. No sense at all to get out in the shop and mill a stock head, even though that is how I really enjoy my retirement. Yup. Get a beer and watch that Housewives of New Jersey show on TV. Maybe get some shell peanuts to crack for my exercise. Get out the computer and order some new 5.5 head from some supplier, play a few hundred games of Solitaire before shutting it down.
Yup, makes more sense than getting out to the shop and doing something that has been done thousands of times already. What a waste that would be.
I guess I will go out to the shop one last time and clean up the Bridgeport, coat it with cosmoline, put a box of sawdust on it with a small electric light too, which will create a dry temperate storage environment. and cover it with shrink wrap. Have a beer, toast Mr. Bridgeport and toast the experiments of Edison and Ford, then go in to bed, turn out the light and dream of sheep, puppy dogs and stock options.

Depends on how far the Piston protrudes out of the block, usually .035 so if you left a .050 counterbore you would be safe. With aftermarket pistons that don't protrude I remove the counterbore completely.
Bill