PinoyDat210 Posted January 25, 2014 Report Share Posted January 25, 2014 if and when necessary to notch relief on stock pistons what tools are required to do at home, and a run down of the process. and how a machine shop would go about performing this procedure and an estimated pricing? Quote Link to comment
zed Posted January 25, 2014 Report Share Posted January 25, 2014 well, I'm definitely not an expert, but Honsowetz' book describes how to use a cutter chucked into a drill, through the valve guides, to cut valve reliefs into piston tops. Maybe one could grind a groove into an old valve and use it as the cutter? He warns about making certain the pistons are properly oriented in the block, and not cutting too deep - a stock piston crown is only about 5/16" thick at the centre. Also, don't leave sharp edges to act as stress risers. Use a micrometer and mark on the valve stem to gauge how deep you cut. Must also check valve to piston clearance carefully after the job is done... Quote Link to comment
difrangia Posted January 25, 2014 Report Share Posted January 25, 2014 well, I'm definitely not an expert, but Honsowetz' book describes how to use a cutter chucked into a drill, through the valve guides, to cut valve reliefs into piston tops. Maybe one could grind a groove into an old valve and use it as the cutter? He warns about making certain the pistons are properly oriented in the block, and not cutting too deep - a stock piston crown is only about 5/16" thick at the centre. Also, don't leave sharp edges to act as stress risers. Use a micrometer and mark on the valve stem to gauge how deep you cut. Must also check valve to piston clearance carefully after the job is done.. As with many procedures, proper depth control is very important !! Whadduz that bring to mind ?? Seriously a collar with a setscrew on the valve stem on the top side of the valve guide would insure uniform depth on all the eyebrows. A little trial & error needed to get to proper depth. Steve Quote Link to comment
PinoyDat210 Posted January 25, 2014 Author Report Share Posted January 25, 2014 i figure it cant be too hard if it becomes neccesary. i mean without a flow chart we'll never really know the gains but if it become necessary to notch the piston using a reground cam and stock internals you probably wouldn't be removing much anyways just a little trim. ya i was thinking of using a drill and cutter. or maybe even a small grinding wheel on a dremel. I heard something about checking the clearance with clay on the valve? not sure about that process. also will reliefs change compression? or affect combustion efficiency? Quote Link to comment
datzenmike Posted January 25, 2014 Report Share Posted January 25, 2014 Not enough to worry about. Quote Link to comment
EricJB Posted January 25, 2014 Report Share Posted January 25, 2014 Put some clay on top of the pistons. Do a mock assembly without the head gasket, and slowly, gently rotate the motor. if there is no contact, you know you have at least the gasket thickness of clearance. Then pull the head off and measure how thick the clay still is. Quote Link to comment
difrangia Posted January 26, 2014 Report Share Posted January 26, 2014 As with many procedures, proper depth control is very important !! Whadduz that bring to mind ?? Seriously a collar with a setscrew on the valve stem on the top side of the valve guide would insure uniform depth on all the eyebrows. A little trial & error needed to get to proper depth. Steve I went back and read my post and it then sounded misleading. Maybe this makes more sense. Seriously a collar with a setscrew as a sloid stop on the valve stem shank of the eyebrow cutter on the top side of the valve guide would insure uniform depth on all the eyebrows. A little trial & error needed to get to proper depth. Steve Quote Link to comment
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