Rage

I am looking for a cutting tool that can be used to increase the depth of the valve relief 'eyebrow' in Merc 496 cast aluminum pistons while the pistons remain in the engine. The tool is installed in the engine valve guide in the place of the valve and is rotated by hand like a thread tap or by electric drill with the head bolted to the block and the piston at top dead center.

I am aware of the Isky Cam tool for this which I have used but it gets dull after about two hyper-eutectic cast aluminum pistons because of the high silica content and then due to its strange cutter design it is totally impossible to sharpen.

I am aware that Manley used to have such a valve relief cutting tool manufactured from an actual valve and hardened but it is no longer available from Manley. I have never used this tool but I am interested if anyone knows where there might still be available a Manley cutter with 3/8 stem for a 496 2.195" to 2.250" diameter valve head if it ever was available in that size.

Any other source for such a tool is solicited.

Any other approach to accomplish increasing the piston valve relief without removing the pistons from the engine nor the engine from the boat is also solicited (excluding doing free hand with air grinder or Dremmel tool).

ratman

i wouldn't think of cutting them myself, take it to a machine shop its only 6 or 8 bucks per piston.

Vinny P

I agree with Ratman. By attempting to cut a valve relief while the piston is in the engine, you will have no way of regulating the depth of the cut. It would be diffficult to get the pistons cut evenly, along with not knowing for sure how much piston material is left. Too thin and you just created a hot spot that may burn through.

woody1

isky cams makes one that works perfectly, used it many a times

Rage

Did you use it on the hypereutectic cast aluminum pistons?

If so did you have to resharpen the Isky tool?

If you ever resharpened the Isky tool how did you do it?

Thanks,

Bill

Rage

WOODY1 used the Isky tool on Ford forged aluminum, not the hypereutectic cast aluminum, pistons so sharpening was never an issue.

Any other such a tools around????????

paradigm shift

How much material are you removing? Balance of motor would be off I would think. Of course I know some that have said balancing a motor that runs no more than 5000rpm is a waste of money.

Sorry no help with tool your are looking for.

Rage

About 1 cc of aluminum has already been removed for a .6 lift cam. I am considering a bigger LSA cam that happens to also have a .62 lift to correct reversion issue. Looking for a better cutter than the Isky I used last time. Plus the deeper you go the less efficient is the cutter even when sharp.