new 2270 blowby

[damo99]

i have a fairly new 2270cc type 4 in my 61bus (2000 klm;s) .
it has 914 heads with 44 x 38 valves , EMW h cam (286 Duration X .488 Lift)
78mm crank , cb super rods . KB 96 pistons, type 1 high volume oil pump .
microsquirt ,CB 40mm throttle bodies 9 to 1 comp ect,
anyway when i drive this i get oil blowback i think it's coming from the
dipstick even though i have put a rubber o ring to try and stop it .
i can;t find anywhere else it could be coming from.
i have breather lines coming from the rocker covers , also 2 from the
oil filler neck and also from the distributor hole (distributorless).
they then go to a 3 liter catch can with air filter on it .
the breather lines are all half inch .
why would i still be getting blowby with all the breathing i have .
every time i go for a drive down the freeway it coats the rear
tray with oil .
i am going to try and get a tiny camera to put in th engine bay and have a look
where it;s definitely coming from
but if anyone has any ideas i would love to hear them

[Piledriver]

There are a few great threads on crankcase ventilation, Ray Greenwood and FJCamper have done a great job documenting successful setups.

The simplest change is getting a couple woven SS ribbon pot scrubbers and stuffing them in the breather chimney (air/oil separators) and lose the breathers at the rocker boxes, or at least on the 3/4 side, as that tends to accumulate oil at cruise speed if vented, the small amount of blow by from the valve guides (exhaust mostly) helps the oil get back to the sump.

The scrubbers being in the case, heat keeps them from getting plugged with vaseline summer or winter, and helps keep the oil in the oil sump.

I run about 5" WC case vacuum at idle or cruise, even a small amount of case vacuum helps the ring seal greatly.
The case vacuum is limited by a small adjustable vacuum break and directed by a check valve to the 3/4 side breather, so flow can only go into the head. You don't want high levels of vacuum on the street as it tends to wear the oil seals.

I run a 1L vacuum accumulator/"catch can" fed by restricted case vacuum via a check valve, larger would be better. This easily could be set up to drain back to the rocker box vent in a Bus.(via a check valve) as you have plenty of room in the engine compartment.

[damo99]

thanks for the info piledriver ,i found the crankcase ventilation thread by fj camper .
it;s a good read .
i still got alot more to read up on

[Piledriver]

IMHO a good PCV setup can sometimes even help fix a marginal ring seal over time.

I used my old oil swilling 400K 1700 as a worst case test pig for various PCV setups for ~200 K miles and by the last ~100K it had ~ zero blow by or oil consumption, and the cylinder bores were beautiful, compression was even and excellent until the end..

I only had to tear it down due to one of the cam thrust surfaces wearing and eventually breaking off, thus making for disturbing bottom end noises at idle from the cam thrashing back and forth for the last ~20K. (I ignored it as long as I could as it still ran great)