Fly Cutting Tooling

HSG

HSG

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Mar 11, 2009
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Does anyone have the information on the tooling and dimensions that we need to fly cut pistons? Its on Roachie's 12 valve. Thanks!!!!
 
Might have to do some measuring of the head and the piston...shouldn't be too hard on a 12 valve.
 
Im looking for the actual bit that goes in the machine. Assuming its a fly cutter?

The operation seems pretty easy, I just want to cut the valve reliefs. Would it just be easier to take them to a machine shop?
 
Most machine shops will already have tooling to do this job, it's not a complicated setup but neither is it cheap to buy just for one job, you will need to tell them where to cut the pistons and how deep to cut. After having the pistons cut I would highly recommend having the set matched for weight.
 
Well, the best way to do it in my opinion is to put an old piston in the cylinder hooked to the rod and crank. Then find some old valves and grind the ends to a point. set the head back on the block and put the ground valves upside down in the guide and hit them with a hammer. Now you know exactly where the center of the relief needs to be. Now you can set up your jig to machine the good pistons.

You need either a CNC mill or a rotary table to clamp on the table of the mill.

If you need to have a valve job done, the valves will move up in the head .040 instead of flycuts.

Or if you have a lathe turn your needed clearance off the top. What cam are you using? how thick of headgasket? has the block head been decked?
 
Im waiting on the cam specs to know the depth needed.

Block will not be decked, head is not known now.

Basically building a kamikaze engine, longevity is not in mind for it.

The ground valves are a good idea, if I can find my old valves is the new problem.

Anyone know the exact tool needed for this?
 
what you building there roachie???
hey need some more info from you tomorrow! i need the lengths between the mount points for a reg cab and mega cab trucks
 
Im building nothing (covers with sheet)

Can do, Ill scribble them all down and get back to you with what will work.
 
might be getting his short bed frame along with the 2wd front and swapping the long bed i have for a short bed he has
 
If you cut the valves deeper in the head it will further shroud the valves. We cut some off of the head to sink the valve down further into the cylinder. Low lift flow numbers come up a good bit. Also be sure to make the cut at least .060" larger in diameter than the face of the valve so that everything can expand and when the valve is slightly sideloaded there is no kissing going on. For marking just put some prussian blue on the face of the valve, install one piston the head and the crank push the valves down to mark the pistons. Needs to be done on a mill unless you are going for major decompress and you can then chop the piston on a lathe.

Zach
 
Hamilton Cams said:
If you cut the valves deeper in the head it will further shroud the valves. We cut some off of the head to sink the valve down further into the cylinder. Low lift flow numbers come up a good bit. Also be sure to make the cut at least .060" larger in diameter than the face of the valve so that everything can expand and when the valve is slightly sideloaded there is no kissing going on. For marking just put some prussian blue on the face of the valve, install one piston the head and the crank push the valves down to mark the pistons. Needs to be done on a mill unless you are going for major decompress and you can then chop the piston on a lathe.

Zach
Click to expand...

Is there any issue with using a ground down valve or punch to mark the location? Just a slight dimple, not a 3# hammer dent. Seems that would be more accurate for finding the center of the valve.

Is milling the top of the pistons with an end mill bit a bad idea? Not to sure if I want to put the 370 pistons in this one.



Tohya said:
If you want an end mill, I'd try MSC.

STANDARD and other SINGLE END MILLS at MSCDirect.com
Click to expand...

Thanks but, I need help there, mill is typically a fancy drill press for me:hehe:

Which one?
 
One that fits in your small mill? :hehe: Since you haven't done this before, buy a large cheap one that fits. Then you have to cut a larger circle out with it.


You may want to practice on something, like a 2x4.


And if your mill is a fancy drill press with a table you can spin. Mount the piston off center so it will cut out the circle size you want when rotated.
 
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I'd use the Prussian Blue idea. Gives the whole diameter of the valve. Might just mark the ridge and then the center of the valve.
 
I think I see something with tripes in the furture. the prussian blue then the center punch might be the way to go.
 
Hamilton Cams said:
If you cut the valves deeper in the head it will further shroud the valves. We cut some off of the head to sink the valve down further into the cylinder. Low lift flow numbers come up a good bit. Also be sure to make the cut at least .060" larger in diameter than the face of the valve so that everything can expand and when the valve is slightly sideloaded there is no kissing going on. For marking just put some prussian blue on the face of the valve, install one piston the head and the crank push the valves down to mark the pistons. Needs to be done on a mill unless you are going for major decompress and you can then chop the piston on a lathe.

Zach
Click to expand...

I said only to move the valves up in the head only if there is a valve job being done. A cutter can be used to remove the material shrouding the valve too.
 
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