Technical smoking on left bank

On my y block I get oil fouling on # 8. It has good compression Is it possible that oil is getting sucked in via a breach in head gasket from the oil return port , it is beside #8

 

Is it possible the oil return is plugged and submerging in oil a bad # 8 valve stem seal and fouling the sparkplug ?

 

Not likely. The pressure in the cylinder when it fires is several hundred pounds and a leaking head gasket would cause a lot of other problems if it were blowing into an oil passage.
Gary's idea is a good one...and a check of the valve seal on that cylinder is a good plan as well. A worn guide will act similarly. A compression check would be a good plan as well, to compare with other cylinders.

 

On a Y block, the only place you can get oil into the cylinder is past the rings or the valve guides. It's pretty much got to be one or the other.

 

thanks for the input , I was just hoping it was top end

 

I bought an OT truck, sbc 400 with dual exhaust.
It was smoking bad out of one side and perfectly clear on the other.
Needless to say that I got a great deal on the vehicle.
I drove it for a few weeks. Diligently checking the oil level.
The number 6 plug fouled and # 8 was worse.
Finally, pulled it in the garage and pulled the head. I immediately noticed that there was something covering the rear oil return hole in the head. Turns out it was the paper gasket from the cap of a quart of oil. About the size of a quarter. Fit there very well.
Reassembled with new stem seals and it runs great.

 

Had a buddy with a 351M engine in his car. Used to start smoking after a while. Pulled valve cover to do valve seals, and discovered the drain back holes were full of sludge. Cleared them out, and no more smoke.

 

The lasttime I had my Y-block heads off I replaced the umbrella seals with positive ones from Competition Products. (Metal base) I bought the tool from Comp Cams and did it with a hand drill motor. My engine has never run so good and all the plugs no longer appear to get any carbon.

 

I thought this was about lighting up a heater in Paree.
I'd go for leaky guides. I've installed umbrella seals on a few cars and it worked...for a bit.

 

Oui, Oui