JessZ Posted June 4, 2006 Share Posted June 4, 2006 175-185Lbs/cylinder is a little high for a L28 isn't it? Quote Link to comment Share on other sites More sharing options...
JessZ Posted June 4, 2006 Author Share Posted June 4, 2006 This L28 pressure read is for a t3 megasquirt application on a N42/N42. Quote Link to comment Share on other sites More sharing options...
racerx260 Posted June 5, 2006 Share Posted June 5, 2006 That motor should be a 8.3 cr motor and compression should be about 170.Could someone have put flat top pistons in it ? that or you have massive carbon buildup.Try a different compression gauge. Quote Link to comment Share on other sites More sharing options...
JessZ Posted June 5, 2006 Author Share Posted June 5, 2006 What a day. I just got done driving 7 hours to pick up this N42/N42 and we gauged the crank case pressure to a solid 170-175 across the board. DAW you mentioned you've seen internally oiled cams on a N47 head, is this not common? The reason I ask is because this N42 head has the internally oiled cam too. I mentioned this to the guy because the other N42 head I have has the "oil bar," not the "oil cam lobes." He said it was a rebuild sent from Japan. Ring a bell anyone? Anyway it was a nightmare trying to get that whole motor into the back on my girlfriend's Saturn. I told the guy to drop the oil before I got there, he said no problem, and that's why 2 quarts drained into the back of the car. Yeah, I should have doubled checked the dip stick:twak: So I'm going to replace the head gasket with a 2mm to drop the compression for the turbo parts I have aquired so graciouly from some of you on HybridZ. I need to reinstall my digi-cam software and start posting, anyway I'm racking out, g-nite. Quote Link to comment Share on other sites More sharing options...
Pyro Posted June 5, 2006 Share Posted June 5, 2006 Pull the head. If it has dished pistons then use a stock head gasket. Don't get hung up on the compression gage reading. Those things can be off by a lot. I have two gages and one always reads 30 psi higher than the other one. Which one is right, who knows? If the timing chain is advanced, it will rise cranking pressure. So, you can reduce cranking pressure by retarding the cam. The chain could be on the third postion which will make the pressure higher. There could also be a lot of carbon build-up in the cylinders. With the cylinder head removed, this can all be seen and corrected. If you pull the head and there are flat top pistons in there, then install a P79 head and run only 8 psi of boost. No problem. Quote Link to comment Share on other sites More sharing options...
JessZ Posted June 7, 2006 Author Share Posted June 7, 2006 This is a internally oiled N42 head. I was saying that my other N42 head has the oil bar, I've not seen a internally oiled N42 head like the one I just picked up from Z-dealer in Oakland. I suppose the cam could have been changed along with the application to make it internally oiled, or maybe there are already internally oiled N42 head, I don't know. BTW, the guy said the motor I bought from him was JDM out of a Z that was rebuilt by Nissan in the 90's in Japan. Is there any way I can tell if this is the case? Quote Link to comment Share on other sites More sharing options...
olie05 Posted June 7, 2006 Share Posted June 7, 2006 I get 210-220 psi across my 6 cyl. I have 10.3:1 CR with: flat-top pistons .040" over N42 head N42 block (not that it changes anything) You should be able to run on pump gas Quote Link to comment Share on other sites More sharing options...
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