Author Topic: Venting fix?  (Read 11228 times)

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Offline Nastytls

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Re: Venting fix?
« Reply #175 on: April 28, 2019, 03:08:41 AM »
Is there such a thing as too much venting? Or another way to put it would be, could adding this additional vent to atmosphere have any adverse affects?

Offline rbabos

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Re: Venting fix?
« Reply #176 on: April 28, 2019, 12:56:19 PM »
Is there such a thing as too much venting? Or another way to put it would be, could adding this additional vent to atmosphere have any adverse affects?
Who knows. I see it as a big mf bandaid for defective head breathers. If they worked well there would be no need for external venting. Venting makes them inoperative for proper function, if they actually seal.
Ron

Offline kd

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Re: Venting fix?
« Reply #177 on: April 28, 2019, 12:59:10 PM »
The MOCO is probably keeping it low profile because they are basically venting to atmosphere now and you know who doesn't like that.  :wink:
KD

Offline roadcaptain

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Re: Venting fix?
« Reply #178 on: April 28, 2019, 01:29:41 PM »
Is there such a thing as too much venting? Or another way to put it would be, could adding this additional vent to atmosphere have any adverse affects?
Who knows. I see it as a big mf bandaid for defective head breathers. If they worked well there would be no need for external venting. Venting makes them inoperative for proper function, if they actually seal.
Ron


Look at the size of the breather bolts in the head, about 1/16"? That's not much considering you've got two 4" pistons pumping air. Then the MoCo sealed off the main bearing on the pinion shaft with the latest version of the oil pump cover. The service manual says the crankcase breathes through the main bearing. So how does the crankcase breathe with the bearing sealed, through the cam bearing? There's not a lot of room for air volume there either. I honestly don't know what is going on here.

Offline rbabos

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Re: Venting fix?
« Reply #179 on: April 28, 2019, 01:34:55 PM »
The MOCO is probably keeping it low profile because they are basically venting to atmosphere now and you know who doesn't like that.  :wink:
No problem. They will just buy the guy lunch and a beer, then business as usual.
Ron

Offline PoorUB

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Re: Venting fix?
« Reply #180 on: April 28, 2019, 02:43:15 PM »
Has anyone here actually hooked up a pressure gauge to the crankcase while riding or on a dyno?

I remember years ago Briggs and Stratton had a spec for crankcase vacuum while running. As far as I know virtually any four cycle engine's crankcase should have a slight vacuum while running.
I am an adult?? When did that happen, and how do I make it stop?!

Offline Rockout Rocker Products

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Re: Venting fix?
« Reply #181 on: April 28, 2019, 04:10:35 PM »
Has anyone here actually hooked up a pressure gauge to the crankcase while riding or on a dyno?

I remember years ago Briggs and Stratton had a spec for crankcase vacuum while running. As far as I know virtually any four cycle engine's crankcase should have a slight vacuum while running.
You can't compare a Briggs & Stratton engine to a.... wait..... carry on.
www.rockout.biz Stop the top end TAPPING!!

Offline rbabos

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Re: Venting fix?
« Reply #182 on: April 28, 2019, 05:21:39 PM »
Has anyone here actually hooked up a pressure gauge to the crankcase while riding or on a dyno?

I remember years ago Briggs and Stratton had a spec for crankcase vacuum while running. As far as I know virtually any four cycle engine's crankcase should have a slight vacuum while running.
On my lawnmower the first few starting revs it has pulses of pressure. It then turns into static- slight negative. Only reason I know this is I tried to run a mikuni pulse fuel pump off the crankcase once. As for all, yup I thought that too. V rod has no umbrella valves, only a 3/16" outlet hole in the canister. A few good out huffs on starting and it does mini in and out of the hole from there. One way valving has been tested on these with a hp gain and less oil into the breather box. To this day I have no idea why Porsche never incorporated them unless it was a cost factor for HD at the time.
Ron