runsstrong Posted April 11, 2006 Report Share Posted April 11, 2006 just wondering what it should be around thanks Quote Link to comment Share on other sites More sharing options...
Old Two-Smoke Posted April 11, 2006 Report Share Posted April 11, 2006 I am suprised none of the builders have jumped in here. When I built my cub I had to recut the domes a bit, if memory serves me I ended up with .036 I didnt like the .024 it was but that dosent mean I was right. I am sure someone else will jump in Quote Link to comment Share on other sites More sharing options...
PassionRE Posted April 11, 2006 Report Share Posted April 11, 2006 (edited) Minimum squish clearance is simply the minimum mechanical limit a engine will not crash the piston into the head...literally , due to heat expansion and rod stretch in the harshest of circumstances. What is MUCH!!!!! more important is squish VELOCITY. It determines WHERE the power is going to be BEST, detonation control is also determined by SQUISH VELOCITY, and you can move it where you want depending if you want best power at peak rpm or best power prior to and up to peak torque curve. It must be calculated though using ex. port timing, bore, stroke, max rpm, squish band width, squish clearance, and compression ratio.... It is NOT a universal number just to be thrown around. especially if SAFE is your concern...Jim Edited April 11, 2006 by PassionRE Quote Link to comment Share on other sites More sharing options...
harley_sr Posted April 12, 2006 Report Share Posted April 12, 2006 Minimum squish clearance is simply the minimum mechanical limit a engine will not crash the piston into the head...literally , due to heat expansion and rod stretch in the harshest of circumstances. What is MUCH!!!!! more important is squish VELOCITY. It determines WHERE the power is going to be BEST, detonation control is also determined by SQUISH VELOCITY, and you can move it where you want depending if you want best power at peak rpm or best power prior to and up to peak torque curve. It must be calculated though using ex. port timing, bore, stroke, max rpm, squish band width, squish clearance, and compression ratio.... It is NOT a universal number just to be thrown around. especially if SAFE is your concern...Jim 500372[/snapback] I was just about to say the same thing.. J/k Jim... Quote Link to comment Share on other sites More sharing options...
Ducman Posted April 12, 2006 Report Share Posted April 12, 2006 Well typically you want it to be at least .030 to not have interference or detonation problems. You could run, and I have talked to people that have run as little as .025 but reliability would be questionable, sooner or later the piston will either hit the dome, or smash carbon buildup into the dome, or you'll get detonation around the edge of the piston and result in a short piston life. Typically .035 is optimum. Probably more than .045 and your combustion starts loosing efficiency. I'm not an expert but at least I didn't give you a blah blah blah answer with no numbers to help you out! Quote Link to comment Share on other sites More sharing options...
runsstrong Posted April 13, 2006 Author Report Share Posted April 13, 2006 thanks ducam thats what i needed to know Quote Link to comment Share on other sites More sharing options...
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