Blow-by and crankcase ventilation-fuel contamination?

[joedrum]

if you raise compression you raise leakage ...i dont see how this would tell anything in my opinion .....i also agree that head shaving not going to make a hill of beans difference in how it runs ....040 shaving is nothing compared to the distance the cam path is ...as far as timing goes ...loose belts causes more timing problems than head shaving ..in my opinion

 

[slabghost]

Keep in mind the oil is being pumped through the motor. It isn't FULL of oil. There is a lot of open space in there with a lot of moving parts that will push air around. Like the insides of the pistons and spinning gear teeth. And yes I agree timing belt tension has a big effect on valve timing.

 

[ekvh]

Where are the belts loose?

 

[slabghost]

When I checked the belts on one of my bikes they were so loose on the tension a quick burst of throttle had the belt slipping on the tensioner. The tensioner actually did catch up later. I checked the tensioners and they both spun free with no binding or wobble. One tightened a bit throttle response improved along with idle.

 

[ekvh]

Tensioned properly they should not have any effect under load. In the wing motor when two pistons are in the way down, two are out, so air in the crank should be pretty evenly displaced. There must be a little blow by. I've just always wondered how much and is it measurable to indicate ring compression condition?

 

[slabghost]

You could fit one of those breath testers from a Dr. on the breather hose and see how far up the ball or disk goes.

 

[mike in idaho]

It's hard to tell how much blowby is acceptable. A leak-down tester will tell you more about the condition of the rings.

 

[slabghost]

.Build a tester.
https://www.google.com/patents/US3411357

 

[dan filipi]

Back in the day smoke out the valve cover oil filler hole was what we used to gauge excessive blow-by. Maybe that doesn't even apply here, I learnt that from my Dad.

 

[Denver]

Back in the early 50's people still adjusted valves, & valve job's were a wear & tear sort of thing, if you ran it hard well, a lot sooner. The spring's metal wasn't as good as it is now. :roll: