Zmanco Posted April 24, 2006 Share Posted April 24, 2006 I'm in the process of rebuilding my N42 block. After hot tanking the shop told me that there was only about .002" between my flat top pistons (not from this block) and the bores, so they could just hone it and not bore it 20 over. I liked this because that meant I wasn't going to have to replace my pistons. However, now that I'm trying to find rings I'm having all kinds of problems. I picked up a set of Perfect Circle std (top chrome ring) and am finding that the end gap is coming in between .020 and .022". The How to Rebuild your Datsun book says .017 is max. I was told that Nissan used to have some .005 over rings, but according to Courtesy Nissan they are NLA. So what do you recommend I do next? Do I have any options besides taking the crank back out, and going .020" over with new pistons? I'm really trying to avoid that expense if I don't have to spend the $$$. Another issue: I had the block honed for chrome rings. But I've also heard how hard it is to seat chrome rings. My car is a weekend toy car, driven hard to 6500 rpm. I've got a mild cam, late model 5 speed and 4.11 so the revs are always above 3k and usually higher. I do a few track days each season. Do I need the durability of chrome top rings, or will cast iron be ok? I've heard that moly-faced would be best, but haven't found a source for L28s. Quote Link to comment Share on other sites More sharing options...
Silent Posted April 24, 2006 Share Posted April 24, 2006 you can run stock rings and be happy for a while. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted April 24, 2006 Author Share Posted April 24, 2006 Silent, how long is "a while"? I really don't want to do this again any time soon as it's expensive and a lot of work. Are we talking about 5-10k miles, or 50k, or 100k? I realize no one can tell me any exact number, but if it's only a few thousand miles (which I doubt) then that would cause me to go with chromes for sure. Quote Link to comment Share on other sites More sharing options...
Silent Posted April 24, 2006 Share Posted April 24, 2006 depends on how hard to drive the car. i run my pretty hard and have no had a problem. then again, im not using l series rings either. {kinda hard to do with a 3.1} Quote Link to comment Share on other sites More sharing options...
78 280zcar Posted April 25, 2006 Share Posted April 25, 2006 I would like to know what you will do too, I just bought the same set of perfect circle (41577) rings with the weird oil ring on it, I have the same problem but it is not that much of a gap. I just went ahead and put them in! Only the top ring is chrome, right? Quote Link to comment Share on other sites More sharing options...
Zmanco Posted April 25, 2006 Author Share Posted April 25, 2006 Only the top ring is chrome, right? Yes, just top ring is chrome. I found a set of Deves cast iron rings that I'll pick up tomorrow. I'm hoping that a different brand will have an end gap within spec. Otherwise I'm thinking it will be boring over .020 and new pistons. $$$ Quote Link to comment Share on other sites More sharing options...
78 280zcar Posted April 25, 2006 Share Posted April 25, 2006 Let me know what happens with the deves rings, I wanted to get cast iron rings in the first place, its just a matter of money! How much do those rings run for? Quote Link to comment Share on other sites More sharing options...
Zmanco Posted April 26, 2006 Author Share Posted April 26, 2006 Let me know what happens with the deves rings, I wanted to get cast iron rings in the first place, its just a matter of money! How much do those rings run for? I picked up a set of the Deves cast iron. End gap measures almost exactly the same, so I guess I have an issue with how my machine shop measured the bores. I guess it's time to take the block, pistons, and rings over tomorrow to work this out. The Deves set were $90.33 before tax. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted April 26, 2006 Author Share Posted April 26, 2006 Now that I have found quality sources for both cast iron and chrome rings, I need to decide which way to go. I really hate the thought that I might have sealing issues and that I would tear it all down again (which leads me to the cast iron) but I also wonder about the cast iron living at high revs (~6500 max) on a NA engine. Any thoughts from those who have tried both? Quote Link to comment Share on other sites More sharing options...
z-ya Posted April 26, 2006 Share Posted April 26, 2006 I used the Deves rings on my F54 flat top rebuild with the stock pistons. The bores were in good shape so I just honed and put new rings and bearings in. The end gap was within spec BTW. The engine has been rock solid relaible, and does not smoke or use oil. It has done three years of track days and autocrosses, so when it is driven, it is driven hard. Made 165WHP when it was NA. It's now supercharged, and getting ready to hit the dyno soon. We'll see how the rings hold out in the new configuration. Quote Link to comment Share on other sites More sharing options...
racerx260 Posted April 26, 2006 Share Posted April 26, 2006 I built a motor with the ring gap like yours and it ran strong but smoked on high speed deceleration.More embarassing than anything else.I wish I hadn't done it.Finally just put in a turbo motor. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted April 29, 2006 Author Share Posted April 29, 2006 FYI, I have found a source besides VB for a .030 over piston set with moly top rings (ITM) and have them ordered. If I was only doing a refresh on a basic transportation vehicle to get another 50k miles out of it, I'd just put it together with what I have now. But with everything apart it just doesn't make sense not to do it right. It's not that much more $$$. That's how I'm rationilizing it Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted May 12, 2006 Share Posted May 12, 2006 so for a stock 280 internals with F54 block.. Deves rings are the way to go? -Ed Quote Link to comment Share on other sites More sharing options...
Zmanco Posted May 12, 2006 Author Share Posted May 12, 2006 I have no personal experience with them other than what was discussed above, but a few people whose opinion I respect have said they are as good as cast iron rings get. No one said anything negative when I was asking around for my rebuild. Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted May 15, 2006 Share Posted May 15, 2006 I just need some good rings, had the OEM ones prematurely fail on me. I found this thread, I don't know alot about the difference between cast iron and chrome moly rings, but they seem to be recomended with the chrome top ring... -Ed Quote Link to comment Share on other sites More sharing options...
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