How To Hold This Part In Lathe?

If theres no blowby, why surface it. If you do surface it use copper sheet metal as a shim and gasket.

Sent from somewhere in East Texas by Jake Parker!
 
Because of the proud combustion chamber you will have to center that part perfectly to face it off. Nike is spot on with using a fixture and the faceplate. MO.

"Billy G"
 
Forget about using the lathe directly.

This is low compression engine so perfection not needed.

You can make a lapping plate so to speak.

Find a chunk of flat round plate and Chuck it in the lathe and make a female mating part that would fit the head.

Next place lathe in back gear and load the part with lapping compound and hold the head against it.

Short periods then test.

Does not need perfection as the gasket will take care of that.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk
 
First, cause no harm. You cannot just go to a store and buy a new head if it is damaged during the surfacing operation. Scrap the head, scrap the engine, perhaps. Mounting it on a face plate can be dicey and it scares me for an irreplaceable part. Kernbigo just beat me to it, but i would lap the head on a flat surface using sandpaper and a surface plate, plate glass, or something KNOWN to be FLAT. You can take your time, and check it with a good straightedge as you go. The gasket will conform to some amount of imperfection at the joint, so don't overdo the surfacing operation. Take your time, do it carefully, make sure to hold the part low down so it stays flat and does not have a tipping component to the lapping, ruining the flatness. Emphasize flat, not pretty, and go no deeper than necessary to make the gasket seal.

Edit: TQ60 beat me to it as well. I need to learn to type faster, or quit eating breakfast while I do this... 8^) I would not use the rotary lapping method for this part. More dicey, less likely to stay flat. You could also take the part to a machine shop and have it Blanchard ground, but where is the personal satisfaction in that?

Second edit: Missed that the center stands proud of the gasket surface. I would still lap it, just on a flat donut shaped plate with abrasive paper.
 
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just a fyi,
shaving a couple thousandths off the heads' thickness won't have any catastrophic consequences, i'm sure the valve to piston clearance is more than sufficient.
you may even get the added boost of a higher compression ratio, by decking the head!!!
if you port match and polish the head on that lil beast, you may get a horse and a half or 2 to the flywheel!
be sure to take a movie of the running engine, i'd love to hear it!
 
Thanks for all the good info!
Just a few comments on what I'm seeing above..
It doesn't show the extent of the rust erosion in the pics. It may be .060 deep in some areas and is beyond lapping, but that was a good idea. Actually the valve stem had rusted clear through & left the valve head laying in the cylinder where I found it..
I'm not trying to get a perfect surface. Heck I'll be quite happy if I can get a continuous ring of flat surface inside of the bolt holes. Then the gasket can do its job.
These engines have loads of space between the valves and piston, like maybe an inch plus.
I do like Techie's idea of mounting it faced towards the chuck. I will look closer at that concept, but I don't know if my lathe can handle that..
Thanks again & keep them coming..
 
This is my first forum post, ....... but hear goes .... if you were to use some type of tapered plug in the bolt holes and have these expand as you tighten them up that would hold the part to some sort of backing arrangement which could be secured in a 4 jaw or faceplate. The projection on the back looks like it is about 4" long would cause a lot of interference and is probable the reason you can't hold it in a 4 jaw chuck. This type of arrangement would stick out about 6" which is a lot of overhang. I would use the tailstock to support the workpiece with some type of plate with a centerdrill hole to sandwich the part between the chuck and the tailstock. This should give the set up enough rigidity to machine the face. A milling machine set-up might be easier but you asked how to do it on a lathe. An alternate might be to set some type of mounting pins in the 4 holes and pull the part down using a bolt through the valve stem holes. ......... or you could use some square stock and pins with a light press fit into the 4 bolt holes for the backing arrangement. Either set up needs the tailstock for support. Good Luck! :)


Jim
 
Air cooled with non water to leak , I think in would spray it he sealing surface with about 6 heavy coats of copper spray a gasket and use a copper head gasket and call it good
 
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