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shaving the head


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also wanting to shave my head for cheap mod. just stroked with 4 mill trinity crank 795 weiscos 65 bore. will be using 110 octane racing fuel. what is the best way to check clearance? i used modeling clay and a steel rule wasnt very accurate but got a jist of where im at now. about .060. how much clearance should be okay with octane im using. also work in a machine shop have thought of a few ways of going about shaving. what is the easiest and best setup to do so?

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Has it ever been shaved before?

 

Check the comp. before you take it off.

 

Check the squish when you reassemble it, and then check the compression again.

 

Make sure you at least use the same thickness or less head gasket when you reassemble it.

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Mine has been shaved .080 which is about a 17cc dome.

 

I already have .30 off of mine. It's a fairly cheap mod instead of buying a Cool Head or something but it does help I noticed a difference. I am going to take .30 more off mine when I get my new cylinders ported.

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what is the minimal head clearance to have and not have any worries? have heard .040 to .060.

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what is the best way to check clearance? i used modeling clay and a steel rule wasnt very accurate but got a jist of where im at now. about .060. how much clearance should be okay with octane im using. also work in a machine shop have thought of a few ways of going about shaving. what is the easiest and best setup to do so?

 

An easy way to check your clearance is with solder. Pull the plug and insert the end of a length of solder, slightly thicker then your expected clearance, into your cylinder. The end should touch the cylinder wall. Crank the motor over once (iginition off). pull the solder out and mike it for thickness.

You can also observe taper in your squish, a slight taper (increase in clearance towards the center of the bore) is usually perfered. Something else to consider is if your pistons are loose in there bores the pistons will rock on the piston pin and give a false reading, so try to use 2 pieces of solder inserted 180deg apart to load the pistoin the same. You can also check it in several locations to see how well your head is centered. If you use a resin or acid filled solder (I perfer it because it is softer) start the motor afterwards to clean any out that may have squirted into the cylinder.

Ban

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Mines .080 and I have no worries :shrug:

 

I think you mean you have it shaved .080...not .080 of squish....there's a difference.

 

Ban posted good info how to check your squish...however, for a correct reading, you need to shove the solder in parallel to the wrist pin. Otherwise, even the normal bit of back and forth rocking in the cylinder will give you a false reading...

 

A piston won't (or shouldn't anyways...) rock side to side due to the wrist pin/rod, but it will rock back and forth...exaggerating the clearance with a false reading.

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