Newly rebuilt engine – oil smoke from one pipe

[oz]

Greetings.
I rebuilt my ’69 302 last early this year and got it running and on the road in the last month. I don’t have many miles on the engine yet but I am concerned because it smokes a little from the left pipe only (just enough to create a slight haze when idling – gets slightly worse on acceleration). When I started up the engine the first time I (long story short) was sucking a bit of oil through the PCV system that ended up running down the #8 runner and made a lot of smoke out the left pipe. I corrected the problem but a small amount of smoke persists. I am quite sure that no liquid oil is getting into the intake at this time. I blueprinted the engine when I built it and all ring gaps were within spec.

The engine is .030” over with flat top hypereutectic pistons and chro-moly rings. It has stock rebuilt heads with screw in studs and roller rockers. The valve covers do not have the baffles (the initial cause of the oil in intake) but I have made changes to eliminate oil use.

Now that I have driven the car some, I need to check the plugs to confirm it is #8 that is using oil but assuming it is - Is it possible I did harm to the rings in #8 during initial startup and cam break in when the cylinder was burning some oil? If this cylinder did not break in then, will it eventually break in and stop using oil?

Any suggestions?

THANKS!

 

[Ozsum2]

This is common. The rings need to "wear in" and you should be bone dry after that.

 

[oz]

Thanks for the reply.

I would also consider this normal except for the fact that 90% of the smoke is from the left pipe... the right pipe is clean.

Since I am not putting out a mosquito repelling amount of smoke, I will probably spend some time on the highway to break in the engine. The smoke is a pet peve of mine though and I hate to see it... it drives me nuts.

I was thinking back on if I could have messed up the oil control spacer. I was pretty deliberate with the build and rechecked everything many times so I don't think this is it. The only possibility of this happening is on a couple of cylinders, the rings came out of the compressor too early and I had pull out the piston to put it back on. Maybe I missed it and the spacer overlapped... I sure hope not. I would think it would be smoking ALOT if this were the case.

Thanks again!

 

[Ozsum2]

Well, you could have something going on in the ring area. Give it a little time, and see. I hope you don't have to go back in.

 

[oz]

I drove it more last night. It does smoke out of both pipes - a little more on the left. (the good news).
It is a substantial fog. (the bad news).

I have rebuilt and engine or two before and never remember having smoke like this long term. Does it have anything to do with the chro-moly rings I used this time? Are they slower to break in the cylinders or something?

 

[crushnut]

Does it have anything to do with the chro-moly rings I used this time? Are they slower to break in the cylinders or something?

Yes, it is a possibility. Chrome rings do take longer to break in compared to cast iron rings and standard moly rings. Do you know what grit stone was used to finish the cylinder walls? For chrome rings it should be a 280 grit stone and a 30 degree cross hatch hone pattern.

What do your plugs look like, black and shiny?

 

[1966conv]

Oil Fog

After I had my motor rebuilt (chrome moly rings also); it smoked a little and used oil up till about 2500 miles.
I ran oil per the builders instructions for 500 miles and then changed to synthetic. At that point I used oil at the rate of 1 qt/80 miles.
After about 1000 mile I talked to the builder and he said the rings had not properly seated yet and to go back to regular oil till it quit using oil (appx 2500) and then I could change back.
I'd give it a little longer.

Good Luck.

 

[oz]

Yes, the plugs are black and shiny. There is oil on the threads when I take them out. A couple of times when I fired it up cold (it's pretty cold in Michigan right now) it had a fouled plug. It cleared out after I ran it for a few minutes and took it to higher rpms.

I only put about 250 miles on it a year (before the rebuild)...
I guess I should get used to the smoke

It has improved slightly in the first 100 miles so I do have hope for it.

Thanks!

 

[allcarfan]

just curious, how did you fix your oil problem after you removed your baffle?

 

[oz]

I picked up a screw in breather from the local auto parts store that has a baffle w/foam in it and a hole in the top. I bought a gromet for the hole on top and installed the PCV there. I ran the pcv hose from the PCV on the right valve cover up and under the lip above the fire wall, across to the left side, down along the intake and up to the vacuum port on the front of the carb. I theroize that the uphill climb that any liquid oil would need to take keeps it from running into the port. It seems to work fine and I was able to hide the hose under the braces and fire wall flange - I tucked it behind the bolts that hold the braces on at the fire wall.