Datsun Roadster Forum-311s.org

Im having an oil burning issue. I checked my compression and Im showing 180,185,190,and 180 for compression (as of 2 weeks ago), but I still burn oil. I went through my head a year and a half ago. I did new valve springs and seals, as well as lapping the valves and installing a new B cam and rockers. My machinest said everthing looked good. So after Solvang I swapped a reground cam in and a few weeks later I noticed the backend of my car was turning black. After getting the carbs tuned and rejetted, it ran better and was burning less oil, but is still burning oil.
Does anyone have any ideas? The head has maybe 4000 miles on it. It seems to run great, but it is making a mess.

Thanks,
Will

I would put as suspect:

1: The head gasket. It might not be sealing right somwhere.
2: The valves. One of them might be bent.
3: The oil pump. Excess pressure.
4: The oil gallies. It might have clog creating excess pressure.
5: The breather hose. The is hose sending oil into your carbs.

If 1, get a new gasket and put some copper seal on it. If not, get a copper gasket - not cheap but nice.

If 2, your cam is off and get new valves.

If 3, replace or dial down the pressure somehow.

If 4, try too flush it out the block. If not, I don't know.

If 5, I don't know.

Will,
You didn't mention valve guides or seals being replaced when you did the head. I imagine they had to have used new seals but if they let the guides go, that could be your issue. That's why mine burns oil. I'll build a new head on of these days.

The oil pressure is fine. The positive crank vent just vents into the air. The valve seals are new (when I redid the head), and if the headgasket were bad, I would have compression issues. I was wondering about the valve guides, and that could make sense. I didn't have the seats and guides done when I had the thing apart. Upon pulling the sparkplugs the #1 plug had a bit of a carbon deposit on the electrode. The rest looked like they were running a little rich (I know they are, I need the next size smaller pilot jets. I have 140s, I need 135s). I am going to run 20/50 oil when I do the oilchange. That might help as well.
Brian- whats the word on that crankshaft?

Will

Will-

If tuning the carbs helped, then I think it might not be an oil-burning issue. It could be you're running rich.

Try venting the breather into some sort of catch can, like a Coke can or something. Run for a while and see what liguid (if any) has accumulated in the can. Sounds like it could be a blow-by problem rather than oil burning. Oil burning will be blue while running fat will be black. Also check the spark plugs for oily deposits or a sooty appearance.

You can figure it out.

Hey SLORoadster you go to SLO High? Some locals spotted a car that as described sounds like yours running around? Did you find the brake parts you needed by the way?
Nothing goes unheard when tied into a small town

No I don't go to SLO High, I am a college student (when I can afford to be). I have the brake parts as well as many many others.
See ya,
Will

Hit me up...let me know when you can catch up this week!