PCV elimination... How critical is it??
Thread Starter
Burning Brakes
Joined: Aug 2000
Posts: 1,211
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PCV elimination... How critical is it??
On my '69bb427/390 I recently switched to full roller rockers and tall (aftermarket) valve covers. I had trouble with the PCV connection as the new valve covers didn't have a built in oil shield/baffle to keep oil from getting sucked out the PCV to the carb. at high RPM. Also, couldn't find a rubber grommet with a baffle that fit a PCV, the ones with the built in rubber baffle only fit the breather caps (1&1/4" opening).
After being frustrated with this situation I just switched over to one breather on each valve cover and eliminated the PCV and also the benefit (if any) that it provides in clearing out blow by gases from the crankcase.
My questions are: Does eliminating the PCV from the engine cause any harm? Does it put more wear on the internals since there (in theory) might be more pressure in the crankcase? Isn't this the way engines used to be back in the pre-PCV days??
Any help or opinions are appreciated. I've been away from the Forum for awhile, glad to see some familiar, as well as new new members here.
Regards, Mark :flag :chevy
After being frustrated with this situation I just switched over to one breather on each valve cover and eliminated the PCV and also the benefit (if any) that it provides in clearing out blow by gases from the crankcase.
My questions are: Does eliminating the PCV from the engine cause any harm? Does it put more wear on the internals since there (in theory) might be more pressure in the crankcase? Isn't this the way engines used to be back in the pre-PCV days??
Any help or opinions are appreciated. I've been away from the Forum for awhile, glad to see some familiar, as well as new new members here.
Regards, Mark :flag :chevy
Le Mans Master
Joined: Apr 2000
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From: cincinnati ohio
St. Jude Donor '09
Re: PCV elimination... How critical is it?? (marky mark)
In the days before pcv they used a pipe from the crankcase to an area below the engine to vent crankcase fumes, called a road draft pipe. I think the theory was the air passing over the end of the pipe would help evacuate the combustion by-products.
I don't think eliminating the pcv is a good idea, you will get fumes in the cockpit along with a much dirtier engine bay.
I drilled my intake behind the carb for the pcv and plumbed a hose to the air cleaner base for fresh air intake. Getting everthing except a filler cap off the valve covers
I don't think eliminating the pcv is a good idea, you will get fumes in the cockpit along with a much dirtier engine bay.
I drilled my intake behind the carb for the pcv and plumbed a hose to the air cleaner base for fresh air intake. Getting everthing except a filler cap off the valve covers
Team Owner
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From: Exiled to Richmond, VA - Finally sold my house in Murfreesboro, TN ?? Corner of "Bumf*&k and 'You've got a purdy mouth'."
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CI-VIII Burnout Champ
St. Jude Donor '06-'10, '13
Re: PCV elimination... How critical is it?? (yellow 72)
The entire PCV/breather set up is there for two basic reasons.
1: vent oil / blowby fumes back into the carb. and engine for a re-burn. Keeps things clean, keeps fumes out of the air, yadda yadda yadda.
2: The vacuum created by the PCV system actually helps the seals of the engine from leaking. Leaking can be accelerated by excessive crankcase pressures. In a small way these pressures push oil past seals and gaskets and create leaks. So, running a good PCV/breather system helps keep the leaks at bay.
If you run a PCV, run a good filtered breather. Some of those cheapy push on breathers can actually allow un-filtered air into the engine. Think of driving down a dirt road with the engine pulling dust into the crankcase :U .
1: vent oil / blowby fumes back into the carb. and engine for a re-burn. Keeps things clean, keeps fumes out of the air, yadda yadda yadda.
2: The vacuum created by the PCV system actually helps the seals of the engine from leaking. Leaking can be accelerated by excessive crankcase pressures. In a small way these pressures push oil past seals and gaskets and create leaks. So, running a good PCV/breather system helps keep the leaks at bay.
If you run a PCV, run a good filtered breather. Some of those cheapy push on breathers can actually allow un-filtered air into the engine. Think of driving down a dirt road with the engine pulling dust into the crankcase :U .
