| bluebus86 |
Thu Mar 03, 2011 1:10 pm |
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the larger diameter the hoses, the better for a breather, 3/4 inch is not too large. there shouold be no low spots in the hoses that will fill with oil liquid and be a like a plumbing trap, air flow will then be restricted.
the idea is to flow the air and vapour well, but all the vapour to condense back to oil liquid and drain back into the motor. a catch can does not allow return of liquid and muct be peridoically dumped.
it is still wise to retian the road draft tube even with a breather set up.
use three hoses, one from each valve cover (mounted high up on cover) and one from the oil filler area. mount breather box high enough so it is all a down hill flow back to the motor |
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| onehappykombi |
Wed Jul 09, 2025 10:04 am |
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volksfiend wrote: vwracerdave wrote: Breather boxes are not necessary until you go above a 1776cc engine or start turning over 5000 RPM.
(Glenn can type faster then I can)
Unless, of course, you run a sand sealed pulley. In that case you will have restricted one of the engines natural sources of air flow, and must therefore compensate with a breather. I, personally, do this to all my engines as I would rather the air entering the crankcase be filtered.
I am barely crossing the limit: built a 1679cc for my bus with a sand seal so I’m having pressure issues. At highway speed the valve cover gaskets will get messed up and the oil dumped on the road.
I already got new valve covers with tabs on them and they help a bit but aren’t a magical solution.
If I don’t want to get vented valve covers, can I just use the filler breather tower and vent to the oil bath cleaner? (I have a mechanical fuel pump so can’t vent there either) I imagine my excess of pressure is minimal so I would like to use the simplest solution.
What are other venting locations that don’t require removing the fuel pump or venting the valve covers?
Any advice appreciated! |
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| Schepp |
Wed Jul 09, 2025 1:53 pm |
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I have a newly built 1600. I started having issues once I crossed the (+) 4500rpm range.
I'm in the process of making my own box with -10an lines. Bigger hoses are better. The filter area of the box also needs to be equally as big or bigger than the hoses combined. Or that volume of air wont be able to escape quick enough.
You cant have a 1" diameter hose and a 1/2" diameter filter. Its like filling your lungs and trying to exhale through a straw.
If the air doesn't have an easy escape path, it'll make its own. Like out the pulley crank snout.
I'm using an older factory oil filler with drain tube. I'm cutting off the small upper outlet and welding on a -10an fitting. Along with vented valve covers. |
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