Box Stock

Venting help

F

fasttommy

Member
I'm running a predator hemi lower end dyno 275 cam rtc8 head milled .070 660 bore methanol carb. We turn 7800 engine is fresh. I plumed it as I normally would pulse fitting on valve cover. And a mother one on top of crankcase to a small dodge pcv valve . I still get slight blow by. Can u guys post pic of how ur venting ur engine and pic of catch can. Thanks
 
It's not blow by. There 2 engines brand new that are doing this . If I turn them 7000 nothing comes out. It's when I turn 7400 and up it's not puking oil . Or worn out rings
 
The only time I every had oil come out was when my rings were wore. I know you said they were fresh and new. It how much of an end gap did you set the rings at?
 
If you have stock size valves and no port work, with that small carb you really are not making power at 7800+ anyways in my opinion. Make sure your ring gaps are clocked right and not lined up first, then do a leak down and make sure they are sealing. You shouldn't need more than the stock valve cover vent with such a mild stock build like you have....maybe one small vent in the block to a catch can. Make sure your pcv valve isn't installed backwards

Most of us vent just like you have yours, but without the pcv valve...meaning strait from the crank case to the catch can, with a breather on the catch can
 
The fact that the engine is turning 7800 RPM is telling me it's making enough horsepower, with that gear ratio, to reach that rpm. How fast it's going, at that RPM with that gear ratio, is another story. Now I'm pretty sure that if you ran the engine on a dyno you would find the horsepower going down at a very steep rate, and I think that's what you're talking about.

Something to try; if your turning 7800 RPM, try taking one tooth off the axle and see what happens. If you lose less than 100 RPM (or pretty close) you're actually going faster. Of course it depends on what gear ratio you are running to start with, but there are resources available to check it out.

It's possible you have too low of a gear ratio, but only experimenting, and some calculations, will prove it.

It's called tuning, and tuning is tough! (Al Nunley)
 
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