And shit compression... I guess the rings aren't seating. 1: 95 2:100 3:90 4:90 5:120 6:100 the plugs look great. Much better than I would think with that kind of low compression. I am not getting that much blow by, at least what I think would be commensurate with such low compression. I have a little bit of oil smoke under heavy boost, but again, not as much as I would think for that kind of compression numbers. I built the motor myself last time, and the rings (same rings, new set on current motor) were seated within about 50 miles, and held compression in the 160's until the cylinder walls got pitted up from leaky head gaskets. Different block, bored with a torque plate. I didn't overload the cylinders with oil on assembly. I checked the tolerances with the shops gauge when I was at the shop picking up the block. I used dino oil for break in. They are wiseco pistons and rings. The top one is chrome, which I have read numerous stories about people never getting them to seat right. I think it had better compression on dry cylinder walls on the stand than it does now when turning over by hand. WTF?? I swear sometimes I want to drive this car over a cliff.
Can you describe your method for compression test? What do you mean turning it over by hand Was this test with it cold or hot What was your procedure for bedding the rings in on first startup? What did you set your piston ring gaps to during the build?
Might be useful to do a leak down test also? Tip for anyone buying a new engine, do a leak down test on the engine before accepting delivery. Could help identify any problems with the build before handing over the final payment
top ring:045 Bottom Ring:055 Hot test, all plugs out, throttle propped wide open and balance tube off. Start up, I started the car, once I knew I had oil pressure, I held it at 2500-3000 rpm while the radiator was burping, took about 20 minutes to get the radiator filled. Once it was off the jacks, I drove it about 9 or 10 miles in second and third gear, revving up to about 5k rpm, and letting off to draw vacuum on the motor. I kept thinking every time I drove it it was finally going to seal up, but now, 250 miles in, still nothing. What is weird is to drive it, you wouldn't know it has such terrible compression. It'll still smoke the tires in first and second at 17 lbs boost. I took it out tonight and ran the piss out of it, bouncing it off the limiter, downshifting up to 6k, etc. Brought it home, and unhooked the fan and let it get up on the hot side, plugged the fan back in, and cooled it down three times like that. Then got it a little hot again, and turned it off. The guy at the machine shop said that he has seen people got between 500 and a thousand miles on chrome rings before they seat, and sometimes they need to get good and hot to seat right. We will see. I know by the time I shut it off, it had gone from drawing about 14 in. of vac at idle to about 17.
seems like you're onto it.. run-in procedure is almost exactly what i do (except i use second gear.. ) id say it just needs a little more time.. i haven't actually compression tested a motor so new before.. usually around 1-2000ks judging by your responses i assume you offset all the ring gaps, and havent done anything silly like line them all up, you seem to know what youre doing also i dont know the composition of dino oil, i always use a mineral oil specifically designed for running in.. hopefully its additives havent glazed the bores keep running it, and wait and see, the alternative is the same now as it will be in a couple of thousand miles
Sorry... Dino oil is a u.s. motorhead colloquialism for conventional motor oil. Straight 30w, non detergent to be exact. The instructions with the wiseco rings had the top ring and bottom ring 180 out from each other, the top oil ring and bottom oil ring about 50 degrees out from each other and the center oil ring at 12:00 on the other side of the piston. I guess the thing that has me alarmed is how quickly they seated when I built it a few years ago.
lol, i googled it.. didnt see much about it if noone comes up with any ah-ha! moments, please report back.. its nice to see threads with closure. have you done a wet compression test and a leak down test to confirm lack of compression is coming from rings? i still think its a little early to be concerned.. just keep driving it like you stole it
that's not many miles on it and if driven like an old lady ..rings will take longer to bed in ..give it some more time. are those ring gaps in mm or thou? .
that's huge, here's your problem imho... should be bore size x .0045- .005 in an application like this, .002 to .006 extra for the second ring, so around .017-.018 top ring .020-.022 second ring...
Imagine getting punched in the gut and simultaneously kicked in the nuts... that's about how I felt when I realized what I had done. I thought that gap seemed awfully big. I remembered back when I built it the first time, I had some expert assistance, and I remember after this little exchange that he had said about 18-19 thou on the top ring, and about 22-24 on the bottom. I completely screwed this up. I know what I am doing for the next few days....sigh. Being human is a real bitch sometimes.
Yeah MV... I have a 4" 320 grit ball hone that I will run down it. The good news is that I don't have to pull the crank and replace the seals. And I also figured out I can pull the heads off with turbos, mani's, etc still attached, so that saves some time. Thanks for the input from all you guys, and not kicking a guy when he's down.
you'd still want to pull the crank to hone so you can clean the block properly afterwards heads do come off with manis attatched, they can be a bit cumbersome and heavy but well worth the effort saved weve all been there mate, youll laugh about it later (quite a while later)
55 thou is a massive ring gap. Do you know what piston to bore clearance you had? Also did you file those rings to that size or just install them as they were
No I sized them... I was being a dumbass and not paying attention. Completely misread the directions that came with the rings. This is only the second time I have built a motor, but still, no excuse. This is partly what I get for staying up working on the car til three or four in the morning in a rush to get it done.
