Guest Venture-Z Posted March 11, 2003 Share Posted March 11, 2003 Can I mill down a set of flat top pistons to lower compression ratio enough to run pump gass on an N-42 L-28 flat-top set up? If so how much would I have to take them down to get about 9.5:1? Would It even be worth doing? Please reply soon, I hope to start on my rebuild this weekend, but I need to figure out wich motor to tear down. Quote Link to comment Share on other sites More sharing options...
Guest Venture-Z Posted March 11, 2003 Share Posted March 11, 2003 Will stock N-42 valves clear the flat tops, what about with a mild street cam? Do I need to flycut the pistons. Is it even worth doing, or should I just stick with the dished pistons. Quote Link to comment Share on other sites More sharing options...
z-ya Posted March 11, 2003 Share Posted March 11, 2003 From what I know, no piston milling is needed, and if you use the stock head gasket thickness, your CR will be around 9.8:1. It's a common upgrade to put an N42 or N47 head on a F54 ZX block with flat tops. Pete Quote Link to comment Share on other sites More sharing options...
Mudge Posted March 11, 2003 Share Posted March 11, 2003 I ran 11.4:1 on pump gas, and have heard of higher, even here in Crapifornia. Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted March 12, 2003 Share Posted March 12, 2003 Although it's not necessary in your application,yes you can mill pistons. The flat tops probably can be milled around .030" without losing any real piston strength integrity at CR's below 10:1. The dished pistons can be milled .080" with no integrity problems. I milled my dished pistons by hand on the floor of my garage using only emory paper and a micrometer to ensure an even cut all around. later,norm Quote Link to comment Share on other sites More sharing options...
Guest Venture-Z Posted March 12, 2003 Share Posted March 12, 2003 Thanks for the info guys, I hope to start my rebuild this weekend. Wish me luck. Quote Link to comment Share on other sites More sharing options...
CruxGNZ Posted March 12, 2003 Share Posted March 12, 2003 Norm, I remember you from when I used to hang out on Zcar.com. I admired your skills. You have a lot of patience! It took you what, a weekend to mill your pistons down with emory cloth? I still like the 12 second time slps for your n/a. !M! Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted March 13, 2003 Share Posted March 13, 2003 Norm' date=' I remember you from when I used to hang out on Zcar.com. I admired your skills. You have [b']a lot[/b] of patience! It took you what, a weekend to mill your pistons down with emory cloth? I still like the 12 second time slps for your n/a. !M! Shaving them .015" was easy. Shaving them .070" for the detonation prone 11.6:1 motor was a BIATCH !!! later Quote Link to comment Share on other sites More sharing options...
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