Why not vent the crankcase directly?

[05softail]

Most people agree to vent the head breathers to atmosphere instead of the air cleaner. Of course this makes sense. No dripping air filter, or oil in the combustion chambers leading to excessive carbon buildup.

Why can't we drill and tap a hole in the cam cover for 1/8 inch npt and fit a 5/16th or 3/8th nipple , run a hose to a crankvent or similar vent valve then to atmosphere (the ground, a catch can, filter, whatever).  This should greatly reduce crank case pressure, allowing the engine to spin more freely (efficiently) and eliminate dipstick ejection and the other above noted common concerns.  I plan on doing this during the winter. Just ordered another cam cover. I figure there is plenty of room to attach a fitting. I'd put it at the 12 o clock position under the air cleaner to minimize the amount of oil mist being pushed out. ( would leave the stock umbrella valves intact and keep my vent tubes to ground as they are)  I've searched for months and could not find any references of this being done. Am I missing something? The crank pressure does not need to go up the pushrod tubes, through the restrictive maze in the heads and through the tiny drillings of the banjo bolts. The top end is oiled through the pushrods via the lifters like any typical pushrod engine. 

Thanks for reading.

Rich


Note: I've never had my dipstick blow out or oil drip from my air cleaner. I just think there has to be a better way.

I'd like to hear pros, cons and opinions of this. Certainly it has been done or at least tried.

[RevFastEddy]

Why not vent the head like S&S does. One head vent to the AC and the other to the back of the carb. It actually pulls a vacuum into the crank case. Nothing ever leaks of drips in to the AC. Makes the dip stick rock solid and hard to pull out when running. Been workin for me the past 9 months.

[GoFast.....]

Why not vent the head like S&S does. One head vent to the AC and the other to the back of the carb. It actually pulls a vacuum into the crank case. Nothing ever leaks of drips in to the AC. Makes the dip stick rock solid and hard to pull out when running. Been workin for me the past 9 months.

It comes down to if you want to burn it which can effect A/F RATIO or spit it on the ground

[crazy joe]

Would you have to much oil carry over with the vent on the cam cover?

[Jeffd]

Most people agree to vent the head breathers to atmosphere instead of the air cleaner. Of course this makes sense. No dripping air filter, or oil in the combustion chambers leading to excessive carbon buildup.

Why can't we drill and tap a hole in the cam cover for 1/8 inch npt and fit a 5/16th or 3/8th nipple , run a hose to a crankvent or similar vent valve then to atmosphere (the ground, a catch can, filter, whatever).  This should greatly reduce crank case pressure, allowing the engine to spin more freely (efficiently) and eliminate dipstick ejection and the other above noted common concerns.  I plan on doing this during the winter. Just ordered another cam cover. I figure there is plenty of room to attach a fitting. I'd put it at the 12 o clock position under the air cleaner to minimize the amount of oil mist being pushed out. ( would leave the stock umbrella valves intact and keep my vent tubes to ground as they are)  I've searched for months and could not find any references of this being done. Am I missing something? The crank pressure does not need to go up the pushrod tubes, through the restrictive maze in the heads and through the tiny drillings of the banjo bolts. The top end is oiled through the pushrods via the lifters like any typical pushrod engine. 

Thanks for reading.

Rich


Note: I've never had my dipstick blow out or oil drip from my air cleaner. I just think there has to be a better way.

I'd like to hear pros, cons and opinions of this. Certainly it has been done or at least tried.

I am pretty sure that is how the R&R cam plate vents.

[maineultraclassic]

I vent mine to the ground, no more dripping air filter or mess on the motor.

Steve

[bob2002]

I'm using Zipper's system to vent to the ground,works great.

[PoorUB]

Why can't we drill and tap a hole in the cam cover for 1/8 inch npt and fit a 5/16th or 3/8th nipple , run a hose to a crankvent or similar vent valve then to atmosphere (the ground, a catch can, filter, whatever).  This should greatly reduce crank case pressure,

One thing about venting the crankcase is to not let any air back INTO the crankcase, the reason for the umbrella valves in the heads. The valves let air out, but not back in. Simply drilling an opening into the valve cover may have a negative affect as it lets air into the crankcase under certain conditions. Toss one way check valve in the vent hose and I may buy the concept!

[Faast Ed]

Using your current vents and running them to the ground is hard to beat. There are already holes in your rocker boxes for them.

I just can't see a reason for drilling into that beautiful chrome for something that really doesn't need doing (in my opinion).

[Mike52]

05softail. If I'm not mistaken, the HD Evo engines used a vent from the crankcase up to about '92-'93, the S&S engines also had them (my '99 S&S did). If you're already venting the head breathers to the ground, it makes no sense to vent the cam cover for the reasons mentioned above. Why try to reinvent the wheel without an engineering degree, there is more to this than drilling a hole and screwing in a fitting.  JMO

Mike

[05softail]

PoorUB:
I would be using a check valve. Krankvent comes to mind. (can't think of the other names at the moment)

Faast Ed:
I have the silver engine so I wouldn't be drilling into a nice chrome cover. However, chrome nipples are available, and braided hose would blend right in.

Thanks for the replies so far guys . Still looking for someone whom has done this, or if there is an overwhelming reason it won't work.  The only obstacle I can visualize is possible excessive oil mist trying to exit (which would necessitate a catch can and frequent draining) . Though maybe running the hose high towards the backbone under the tank and putting the check valve at least 6 inches from the nipple may limit the oil due to gravity.

[Bagger]

Have you seen the Feuling setup?

OIL TANK BREATHER KITS
•   Stop dipstick blowout
•   Releases power robbing pressures from oil tank & crank case, reduces blow - by
•   Promotes proper oil flow and oil tank function

http://feulingparts.com/wp/feuling/v-twin/harley/oil-tank-breather-kits/oil-tank-breather-kits/

[05softail]

Hey Mike. Your input is always held in high regard. I agree that if nothing is to be gained then it's a waste of time. I am guilty of trying to reinvent the wheel without an engineering degree  (especially in the winter)

I just can't see how the factory head breathers can adequately evacuate these pressures.  Large pistons, single crank pin, very small crankcase, ect

Science is fun!  I will drill a hole under the timer cover plate into the cam chest. (cam cover removed for drilling of course) Tap the hole for my pressure/vacuum gauge and zip tie the gauge to the dash. Then I can see whats going on in there while riding. If there's no excessive pressure in the crankcase wide open on the highway then I'll ditch the idea.  Hopefully get this experiment done by the weekend.   

[Mike52]

Science is fun!  I will drill a hole under the timer cover plate into the cam chest. (cam cover removed for drilling of course) Tap the hole for my pressure/vacuum gauge and zip tie the gauge to the dash. Then I can see whats going on in there while riding. If there's no excessive pressure in the crankcase wide open on the highway then I'll ditch the idea.  Hopefully get this experiment done by the weekend.   

Now you're thinking, this makes more sense before the breather project, learn something before committing to it.

Mike

[djl]

Science is fun!  I will drill a hole under the timer cover plate into the cam chest. (cam cover removed for drilling of course) Tap the hole for my pressure/vacuum gauge and zip tie the gauge to the dash. Then I can see whats going on in there while riding. If there's no excessive pressure in the crankcase wide open on the highway then I'll ditch the idea.  Hopefully get this experiment done by the weekend.   

05, please post the results of your experiment when you have them.

[ICANTD55]

I have been kicking around this idea for a while and outlined it in one of Munkys post a while back on the old sight.I have not tried it yet havent had the time but already have the spare cover.I was gonna drill at the top of the cover directly over the cam plate. Then run it to a catch can on the right down tube but I was gonna try to find a pcv valve and a restrictor so I could let it drain back into the sump on shutdown from the bottom of the tank whithout haveing to drain it manually. Restrictor in the botton hose pcv in the top.

[ICANTD55]

Please post your findings,I am very interested in how things turn out. Good luck.
Rick

[hogmandon]

S&S makes a crank case breather reed valve that creats a slight vacumn in the bottom end and no more oil in the tb. I put one on a year ago and it works great and no more oil drips. Look in the S&S engine kit section part # 31-2070 fits behind the oil pump up to 06. I don't think it fits newer bikes

[05softail]

Thanks guys for the info and encouragement.
This is my only vehicle. I hope to have the time on Saturday night to tap the cover for the gauge. Sunday is 6 days away, but so far no snow or rain in the forecast.    I will post my findings as soon as I have it.

[Don D]

This is a good topic but first off HD did not just throw spagetti at the wall on this one and see if it sticks. There was considerable engineering involved. This oiling system was a big departure from the EVO and other previous models.
The S&S crank vent IMO a mistake and one of the few products they make that is not well engineered for the stock TC cases. Works fine with their cases. I could elaborate but on this topic of open crankcases...
The TC relies on the piston downpressure and a slight bit of oil in the sump to lubricate the main bearings. This means the TC breaths from the crank case to the cam chest and then up to the rocker boxes when the piston is on the down stroke. If I am understanding the circuit right the mist that is released through the breathers is just positive pressure above and beyond the piston going up and down which is a net of zero pressure. This positive pressure should be minimal if the rings are sealing properly. Many are not and this is likely to be the root cause of carry over for many. When the piston goes up the suction pulls the oil out of the top end and to the cam chest, through the right main bearing and back to sump. The two stages of the oil pump balances oil supply and scavenge so there is balance there.
Open the crankcase to atmosphere and now you are relying on gravity alone to get the oil from the top to bottom and have cut the oil circulating through the main bearing filling up the cam chest and not going back to the crankcase. Could be a problem right? Bottom line is research this throughly before diving in. The R&R cover is a lot more than just a drilled hole to let out pressure.
Breathers after the umbrella valves to the ground is a benign change in this circuit and just gets the mist (and that is all it should be) out of the intake stream and can help prevent carbon build-up and pinging.

[blackhillsken]

A couple years ago I had FastFLSTF Mike's Softail 121" motor apart and figured that would be the time to drill & tap a hole into the crankcase for testing once it was together.  The hole was on the top of the case behind the rear cylinder (into the flywheel chamber).
So............ got it together and up on the dyno for the testing!  Ran a 3/8 hose up from the fitting to about frame backbone height and tried it totally open first, then with an auto PCV valve at the end one way, then reversed it.

No difference in horsepower or torque during any of the testing.  The only reason it wasn't left in there for long term testing was I was nervous about losing some of the blow-through oil mist that lubes the right side crank bearing.

There's a nice 1/4 NPT plug in that hole now.

[ICANTD55]

Not sure that the MOCO had large displacement motors in mind when the came up with there  breather system . Maybe the same guy designed the cranks also?
Don Aside from a little larger scavanging hole for the pump what are the other differances between the S&S cases ?
That would make the read valve more efective on the S&S  cases.
Very interested in this .
I started a new tread for the Breather valve so we dont hijack 05's tread.

[itsafatboy]

The RR cam plate does just that it vents Crank pressure out the cam plate but it runs it through a labrynth first to separate the air and oil, then on the vent line comming off the side you could run a krank vent or just a catch can i ran a line to one of those small golan catch cans its all very neat and hard to see

[jsachs1]

The S&S vent rear head,vacum front head is NOT foolproof.
I've had to change a lot of them to breath out of the rear of the case.Just remove the pipe plug,install hose barb,and an auto parts PCV valve,or another S&S black & white oneway valve.
John
Not trying to hi-jack thread.