b-nasty Posted June 28, 2010 Report Posted June 28, 2010 Putting the 421 toghether and did a compression check, Only had around 75psi and Couldnt get a squish reading. Dont know what the heck is going on. Everything seemed ok when I took the head off. Its a 4mm cranks, cub cylinder, blaster pistons, and a RDZ head with 20cc domes. Do they have to be RDZ domes? Let me know what you guys think. thanks Quote
RadarRacing Posted June 28, 2010 Report Posted June 28, 2010 Domes for a blaster piston are different than banshee pistons by quite a bit. Also domes for a stock cyl 4 mil crank are different. You probably have a bad match on something. If you call Jeff at FAST he is very good at getting that lined out. Quote
dajogejr Posted July 8, 2010 Report Posted July 8, 2010 Since RDZ is now a site sponsor...why don't you ask him Directly? http://bansheehq.com/forums/index.php?showuser=36089 Quote
sleeper06 Posted July 12, 2010 Report Posted July 12, 2010 also cut domes will not work because of the deck height being almost zero,so if your domes are cut for a 4mil squish would be non existent Quote
dajogejr Posted July 12, 2010 Report Posted July 12, 2010 also cut domes will not work because of the deck height being almost zero,so if your domes are cut for a 4mil squish would be non existent Not really...it would be 2mm plus the actual squish...LOL. Do yourself a favor...measure deck height. That's how far the piston sticks out of the bore at the edges. It is quite possible there is a mixup and you got the wrong parts. It happens. Quote
drap660 Posted July 12, 2010 Report Posted July 12, 2010 (edited) Are you sure the 4mm crank is a 115 rod and not a 110mm? That would be an issue. Edited July 12, 2010 by drap660 Quote
b-nasty Posted July 13, 2010 Author Report Posted July 13, 2010 Got the problem all figures out. Ordered some 21cc domes for the blaster pistons. Squish was at .053 and compression was good. Need to double check with another compression guage. Quote
RadarRacing Posted July 13, 2010 Report Posted July 13, 2010 still kinda sounds like you have about .010 thous too thick of a base gasket but should be close enough unless you are still about 10-20 psi short of what you are wanting it may be short on bottomend since its a pumpgas motor depending on what you weigh. Quote
b-nasty Posted July 14, 2010 Author Report Posted July 14, 2010 Its an alky motor, F.A.S.T told me to go with the 21cc domes. Quote
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