I'm going to get a set of those cool cast aluminum valve covers with the raised chevrolet and bowtie. The valve covers are sealed, and have no holes for oil fill, or breathers. What effect will this have, if any. I was told it would give me more vacuum, but I don't know. Should I get holes drilled in them.(?)

 

The motor really does need some way to ventilate the crankcase effectivly, and breathers do an excellent job. You may see some hp loss without breathers, you may not, but my personal experience was a loss.

Hope this helps.

 

ny 383 wouldnt even run right without 1

 

More Vacuum!!!!! LOL

You will build pressure in the crankcase and possibly blow some seals out or at least cause some leaks. Pressure in the crankcase makes it harder for the motor to pull the pistons back down and will force oil up past the rings into the combustion chamber.

Best thing to do would be to put a vacuum pump on, then you will gain power.

This should all, not be confused with intake vacuum and pressure. Different beast.

Hence: PCV ( positive crankcase ventilation). Just drill the holes and mount it back up.

Dave Brown
Wheels Up Racing
http://www.fastrides.net/board/image...e893644c6f.jpg

 

I drilled holes where I wanted and welded aluminum bungs onto the valve covers. I use threaded fittings and hook my crankcase breather hoses to my header evac system.

If I was going to do it again, I'd go for a cleaner look and just drill and tap a pipe thread hole for the fittings to screw into.

You do need some sort of breather even if it's just in one cover. Crankcase pressure will build up and you'll have more oil leaks than normal.

Because mine only have fittings in them I have no way to add oil to the engine. Changing the oil means pulling a valve cover to get oil in.

 

Remmeber, header EVAC systems only work when you are running without mufflers.

Dave

 

What's a muffler? My exhaust system consists of short turnouts attached to the headers so that the alcohol fumes exit out the sides instead of under the car.

Things why you can't use header evacs with mufflers:
Mufflers create backpressure and they won't suck the crankcase gasses out properly. They will still suck but not very well.
Lots of nasties in the crankcase. Oil and water vapor will condense in the muffler and cause more problems.

If you can't provide a proper crankcase evac system, it's best to just have open (filtered) breathers. Using a PCV just sucks the oil and water vapor back into the engine. Water doesn't burn.

 

I'm running a pair of the Moroso breathers on mine.
http://static.summitracing.com/globa.../mor-68730.jpg

Should do the job just fine.

 

The raised chevrolet valve covers are my favorite. I just wished they made them in center bolt valve covers.

 

I picked up about 10 hp on top by adding a breather. But then again my rings took their time to seat and probably was getting some blowby.

Put it on a dyno with your old valve covers and then with your new ones. See if there is a difference, then you will know for sure.