shanYE west Posted December 30, 2008 Report Share Posted December 30, 2008 Yeah.. it ran good until the skirt broke in about 2 hours or so.. Quote Link to comment Share on other sites More sharing options...
BUILDER Posted December 30, 2008 Report Share Posted December 30, 2008 It ran good? One more vote for not modding them. I was going to have my pistons done when i did my 4 mill and they told me not to do it. They said it was not worth doing it and most people that do have the skirts break on the pistons. Quote Link to comment Share on other sites More sharing options...
uwenr Posted December 30, 2008 Author Report Share Posted December 30, 2008 He has a custom ash tray... LOL. Any thoughts on the over revving? Quote Link to comment Share on other sites More sharing options...
deckheight Posted December 30, 2008 Report Share Posted December 30, 2008 (edited) There's a reason it's just the right tube, maybe multiple reasons??? I'm guessing between windowing the pistons and something else??? Good pics of both pistons (good one and bad one) would help. Top and bottom of piston crown, wrist pin removed. I also agree w/everyone else... I do not believe increasing piston window time area is doing much for you performance wise. on edit: Wouldn't think rpm is it. What ignition you using? Edited December 30, 2008 by deckheight Quote Link to comment Share on other sites More sharing options...
dajogejr Posted December 30, 2008 Report Share Posted December 30, 2008 Shot in the total dark... Crank bearing going bad? Quote Link to comment Share on other sites More sharing options...
uwenr Posted December 30, 2008 Author Report Share Posted December 30, 2008 Shot in the total dark... Crank bearing going bad? What do I look for? Quote Link to comment Share on other sites More sharing options...
sheefreak Posted December 30, 2008 Report Share Posted December 30, 2008 What do I look for? With the top end off the cases grab the rod while keeping the crank from rotating and pull straight up and down and see if you have wiggle room. You should have virtually none. Quote Link to comment Share on other sites More sharing options...
sheefreak Posted December 30, 2008 Report Share Posted December 30, 2008 He has a custom ash tray... LOL. LOL! Quote Link to comment Share on other sites More sharing options...
uwenr Posted December 30, 2008 Author Report Share Posted December 30, 2008 With the top end off the cases grab the rod while keeping the crank from rotating and pull straight up and down and see if you have wiggle room. You should have virtually none. Too late for that, cases are already split and being welded. Cylinders being bored, trying to get it together for the new years race. Quote Link to comment Share on other sites More sharing options...
KEVSWS6 Posted December 31, 2008 Report Share Posted December 31, 2008 I know I go against the grain here but I cut all my pistons up. The only two I had ever go bad is when someone else did it. I see your pictures and they look fine as far as the window cut. Are they cutting the side skirt also? Tight radius on that area and they let go. I would guess on a detonation problem like dajogejr said. You would start with your UCCR or static PSI. Cut of your dome. Clearance of your piston ATDC. Timing plays into this also. What are you running for ignition? You still have a bridged intake right? I have seen people cut the bridge out and wonder why the pistons keep breaking on the intake side Quote Link to comment Share on other sites More sharing options...
uwenr Posted December 31, 2008 Author Report Share Posted December 31, 2008 I know I go against the grain here but I cut all my pistons up. The only two I had ever go bad is when someone else did it. I see your pictures and they look fine as far as the window cut. Are they cutting the side skirt also? Tight radius on that area and they let go. I would guess on a detonation problem like dajogejr said. You would start with your UCCR or static PSI. Cut of your dome. Clearance of your piston ATDC. Timing plays into this also. What are you running for ignition? You still have a bridged intake right? I have seen people cut the bridge out and wonder why the pistons keep breaking on the intake side The timing is at +6 the last time i checked the compression it was 155. The domes i dont know about. The piston window is only cut on the intakes not the sides or the bottom and the intake windows only get cut on the top as you can see in the pics the bottom corner thats cracking is the stock location for a blaster. Quote Link to comment Share on other sites More sharing options...
firebanshee Posted January 1, 2009 Report Share Posted January 1, 2009 How long are your connecting rods ? Quote Link to comment Share on other sites More sharing options...
KEVSWS6 Posted January 1, 2009 Report Share Posted January 1, 2009 The timing is at +6 the last time i checked the compression it was 155. The domes i dont know about. The piston window is only cut on the intakes not the sides or the bottom and the intake windows only get cut on the top as you can see in the pics the bottom corner thats cracking is the stock location for a blaster. Well that is plenty safe. Quote Link to comment Share on other sites More sharing options...
uwenr Posted January 2, 2009 Author Report Share Posted January 2, 2009 (edited) Nope...drop them in.I've never seen proof that windowing a piston does anything notable on the track or performance otherwise. I have seen a few broken skirts. I would drop them in. Don't touch a thing. A loose bore in addition to a weakened skirt could very well be an issue... Process of elimination. Talked to another builder last night and he said he cuts windows in everything above a mild port. This is a very reputable builder holding some P.S. records from 2008. He said over revving with the sloppy sleeve caused it. Edited January 2, 2009 by uwenr Quote Link to comment Share on other sites More sharing options...
dajogejr Posted January 2, 2009 Report Share Posted January 2, 2009 Cool...get to cutting your next set of pistons... Just trying to figure out why you asked the question when it seems you already had your mind made up?? Quote Link to comment Share on other sites More sharing options...
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