Whats the best way to to vent my motor? I just switched to carb and I went to fabricated outside bolt valve covers. I have to drill my holes for the breathers. Has anyone done this? Any tips? Should I go breather and PCV or run two breathers with no PCV (it looks alot better)?

My buddy went with two breathers and the pressure in the engine kept blowing out his front oil pan gasket till he removed one. But I do see cars run with two breathers at car shows all the time. Whats the deal?

Is there any good reason to run a crank case evacuation pump? I here it helps with power. Does anyone have any expperiance with these pumps?

I know its allot at once but I would like to cover the whole situation if possible. Thanks!!

 

Drill the holes and run a proper PCV system (with valve).

PCV systems use engine vacuum to pull out the crankcase vapors whereas dual breathes have to wait until excessive pressure is built up and then it self-vents.

 

a guy i use drag with used a bung welded into his collector and a 1 way check valve and then conected it to the breather hole on the valve covor, so at higher rpm the ext would make a huge amount of vac. ive seen it for sale in summit but i forget the cost

 

Use a PCV in one valve cover and a breather in the other.

 

That system doesn't work worth **** on the street. Use a PCV system.

 

If you can't install a oil baffle under the PCV valve hole in your valve covers then install a paper elemement fuel filter in the PCV hose to ensure no oil get drawn from the valve covers into the engine thru the PCV. be sure to drill the PCV fitting hole in the valve cover so that it is not directly over a rocker arm. That way oil will not be directly sprayed onto the PCV from the rocker arm oil port.

Use a functional PCV system on any street driven car. Other wise the carb will run rich if the PCV is not hooked up and working. The carb's idle circuit is calibrated to allow for the slight air leak from the PCV valve. If you eliminate it, the carb will not function as designed and you'll just have one more tuning headache. (Rich idle, incorrect throttle blade position at idle)
There is no downside to useing a PCV, but lots of down side to not using one.

 

negative pressure (vaccum) in the crankcase is the opposite of positive pressure in the cylinder during firing stroke--- it helps the rings seal the combustion event better. crankcase vaccum pumps are the next step above the vaccum the engine makes through the pcv valve, but are expensive. unless you're trying to get that last couple of hundredths in the quarter, I wouldn't worry about it. The dual breathers offer NO vaccum in the crankcase, plus will "seep" oil all over the valve covers eventually, and can also leave dangerous combustion gasses in the crankcase (blow by from the rings), which if is too fuel rich can ignite and literally blow the valve covers off.

the "vac-u-pan" systems work well, but like air_adam said, they're mostly for racing where there's LOTS of volume of exhaust gasses going out the headers (quarter mile pass), but are somewhat ineffective in an idling or part throttle operating engine.

use the pcv system with one filter (inlet to the crankcase) in one valve cover, and the pcv valve hooked to manifold vaccum (below the throttle blades), that'll fix you up.

 

Just to clarify... A PCV system does not create a vacuum in the crank case. It is a Ventilation System. the crank case will be very near atmospheric pressure when the engine is idleing. The PCV just draws air thru one valve cover (vented)
through the crank case than then out the other valve cover
thru the PCV valve and into the intake manifold at the carb base. You want airlfow thru the crankcase, not vacuum in the crank case. The PCV valve has a defined flow restriction to regulate how much airflow is created thou the system to purge combustion gasses from the crank case.

A racing crankcase evac system is a different beast entirely. Different purpose. Won't work at idle. Often won't work thru mufflers. Needs an open exhaust system.

 

Here is a link to a Crankcase Evacuatiuon system that is supposed to be street friendly. I think I may give it a try. What you guys think?

http://www.diabolicalperformance.com...caseevac2.html


Anyone have any ideas on how to drill the holes in the valve cover if I decide to use the PCV?

 

That looks like a good way to make your car faster, by reducing weight. In particular, the weight savings will be concentrated at the driver's wallet.

Put a normal PCV system on it, with a regular PCV valve in one valve cover with an oil separator/baffle under it, and a source of CLEAN FILTERED air into the other VC, also with an oil separator under it.

 

My new covers are sheet matal fabricated and super trick but they don't have holes or baffles. How do I get the separator/ baffle you speak of for non baffled covers?

 

You make it. Drill a hole, fab up a little sheet metal baffle and weld it in place.

 

What if ya ran it like a sand drag or other car where they run hose
from the valve covers to just after the headers. So the engine scavanges its self and keeps pressure equal above and below the piston?

Looks **** too

 

Seen several similar post bu using electric vac pumps used on many GM cars. Not all are suited for it but my 2.8 has one in its system.