240hoke Posted January 2, 2004 Share Posted January 2, 2004 Hey guys, I got a set of Hastings rings from Topend Performance for my enigne. I was getting ready to put everything back together and checked the ring gaps. They seem to be very excessive, all with a gap of .020-.021". According to the little equation .004"Xdiameter the l28 should have a gap of .014". I have also checked the bore and it came out dead on (3.386", I believe) I searched on the 6 cylinder tech board and found one other guy that had this exact problem with beck-arnley(sp?) rings. There was only one reply to the post so i thought i would try here. what do you guys think, do I need a new set? or is .020" tolerable? Thanks Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted January 2, 2004 Share Posted January 2, 2004 Go with factory spec, no sense putting the engine together and having excessive blowby or lower compression then you should. YOu could always ask for 1mm oversize and file to fit. Quote Link to comment Share on other sites More sharing options...
240hoke Posted January 2, 2004 Author Share Posted January 2, 2004 Aight guys, i slid a couple of my old rings in there (6K miles) and they also have ~.020" clearences. I searched around on zcar.com and found that some others had had this same issue with pre-fit rings. Also got a mix of replies, some suggested not to use them while others said they were fine. I know that my car ran fine before and that It wasnt using any oil. I had minor blowby but nothing excessive. Also one question to add in here, what are you guys reading for your compression on a stock l28et? im gettting 155psi. What would you guys do? -Austin Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted January 2, 2004 Share Posted January 2, 2004 Do you have a factory manual, see what it says. I like mine tighter, but the engine takes longer to break in that way. I have between 150 to 160 psi cranking pressure cold, but I don't have stock pistons. Quote Link to comment Share on other sites More sharing options...
240hoke Posted January 2, 2004 Author Share Posted January 2, 2004 I dont have a factory manual, but I have the "how to rebuild your datsun/nissan engine" book. It specifies a gap of ~.014", and that between .012"-.017" is tolerable. Just curious if anybody else has used these pregaps rings with .020" tolerances and what there expiriences have been, I mean like i mentioned earlier the old rings were gapped this way so i think that i will be fine. I m thinking about going ahead and putting in the pistons. -Austin Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted January 10, 2004 Share Posted January 10, 2004 I got some rings from VB they were the beck arnley type, they had excessive ring gap, so I got another set that cost more and they also had excessive ring gap. I can't remember exactly what the gap was, but it was over .40mm, max spec is like .33mm. I ran them anyway and haven't had any problems that I can attribute to piston rings. I will check my compression tomorrow. Hopefully it's good! I think .33mm is .0130in Quote Link to comment Share on other sites More sharing options...
240hoke Posted January 10, 2004 Author Share Posted January 10, 2004 I went ahead a put them in, they all had a gap of about .020 - .021" so im hoping they will be alright. ive almost got hte engine ready to go in the car, should be running in a week or so -Austin Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted January 10, 2004 Share Posted January 10, 2004 that's probably pretty similar to the gap I had. I used metric gauges because metric is much easier. Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted January 15, 2004 Share Posted January 15, 2004 ok I have done two compression checks on my engine. one when it was still cold (forgot I had to warm it up first) and the compression was around 130-135 on all cylinders. then today I did a hot test, after finding out that my engine has been detonating under full boost and was smoking a little bit. compression was around 110-120 on all cylinders. And the compression went up slightly when I dumped some lightweight oil in there (not engine oil though) Now, I think the compression was higher before but I didn't do a hot test. Maybe I damaged my rings? possible. It doesn't make any extra sound on stock boost after I took out the controller. I re-used the stock pistons and just honed the cylinder walls when I rebuilt the motor. The car still runs great, I have to check on the smoking again in the daytime, but I guess I am probably not producing the power I should be because of the lower compression. Maybe running those excessive gap rings is not a good idea after all. Quote Link to comment Share on other sites More sharing options...
CU Zcar Posted January 16, 2004 Share Posted January 16, 2004 I was probably that guy with the Beck Arnley rings, I remember posting about it. I used them anyway with whatever gap it was I said I had, and it doesn't seem to be a problem. I haven't ever checked my compression though. The engine doesn't seem to be hurting for power or burning (much) oil. Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted January 16, 2004 Share Posted January 16, 2004 mine still has lots of power, but I guess it's possible that it's not as much as it should be making. I am not overly concerned with the lower compression yet, it only started to smoke yesturday and it was just a little bit. but I think I might have damaged it with the detonation that I miss diagnosed so many times. Quote Link to comment Share on other sites More sharing options...
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