This past winter I rebuilt my motor, well actually I had to buy a new/used block because I cracked a sleeve in my original block. I ended up getting a C5 block that was from a Real Time Racing (RTR) ITR, and yes it is really from RTR. Anyway, it had already been bored over a little and I was planning to go with CTR OS pistons so it was not that big of a deal. The machine shop that I took it to to be cleaned and a fresh hone job said that it would be fine and that the bores would not be to big. The deck and head were also straight. Oh yeah.....my original motor never burned any oil, it was one of the few ITR's that didn't burn any.
So the assembly went fine, the entire bottom end was balanced a blueprinted. Everything worked out fine, the only small issue was that the ring gaps were a tad on the loose side, some were ok but some were anywhere from .002 - .003 bigger that factory spec. I asked around and pretty much he consensus was that that would not make that much of a difference. So the block went back together and into the the car.
During the break-in period everything was fine, no problems, never smelled anything that I should not have, did not lose any oil, all seemed well. During my first few bursts into vtec I started to smell a little bit of burning but not really anything to be concerned about. But then when I took the car to the dyno and really started to get on it it was just pouring this thick black stank smoke out the exhaust pipe. During the course of the day it went though 2 quarts of oil on the dyno. We pulled the plugs and they seemed a little darker than they should have but not oily, so we did a compression test. I can't remember the numbers exactly but I do remember that they were fine.
So over the course of the next few days I did not really beat on the car at all, just kept is under 5800 rpm. I kept thinking about what it could be, and I really only came up with three things: (1) the rings, (2) the valve seals or (3) the head gasket. I had replaced the valve seals when I rebuilt the motor but I thought I migh not have put them in correctly, so I ordered more from Len at Baranco. The compression test told me that it was not the head gasket and probably not the rings, so I pulled the head off and changed the valve seals again, but this time I changed them alot more carefully.
When I did pull the head I noticed that the exhaust valves were caked in carbon build up while the intake valves still looked perfectly clean and everything else looked fine including the head gasket. I cleaned the exhaust valves as best I could and put everything back together.
I went out for a drive and noticed that it seemed a little better, but it was still burning oil. Although the smoke was now alot lighter in color and not as heavy. I pulled the plugs and noticed that this time they were pretty saturated with oil. SoI did another compression test and the number were ok (1) 255 (2) 250 (3) 245 (4) 260. I would like to do a leak down test, but don't have a tester, I have been trying to borrow one from someone on HT but nobody has responded.
So does anybody have any ideas as to what might be wrong with my motor? Any thoughts would be of service, thanks.

Justin

 

I know you know Black smoke is gas and did you check the PVC ?

 

You need a leak down test ASAP. If you cannot find one, go to a decent shop in your area that will look at it for you. Don't wanna be doing unnecessary damage to your engine. Good luck

 

iif u are using oversized ctr pistons then those compression numbers are a bit low. You should easily be hitting over 280 psi if not 300. I had two rebuilds with ctr pistons i hit nothing less than 300psi, on two different testers, right now i have a 97 spec jdm itr motor and i hit 270 staight across. I think its the rings

 

Well would those compression numbers be different if I had a milled deck and a different thickness head gasket? My deck was milled .030 and my head gasket is a Cometic MLS .078.

 

they should be higher even with the gasket and and especially the milling. Remember ctr pistons in a b18c5, the compression ratio is 12:3:1 in a b18c1 its 12:5:1

 

I wanted to keep the compression under 12.1:1, so I am pretty sure that with the thicker head gasket we figured it was somewhere between 11.8:1 and 12.0:1.

 

my bad its 12:1 in a C5 and 12:3:1 in a C1