enginehistory.org

[jwilcox]

The R 2600 is starting to go together, I've been thinking (dangerous) am I correct that any valve/pushrod cavity from the case on the push rod tube to the valve on a lower cylinder would always be full of oil? Never thought about it but there are no drains and no way I see for the oil to get out. Book says the lower intakes are not pressure fed and get oil from drip but the exhaust would for sure always be full. I have a book with some info on the 1820 and it appears to have valve cover drains, any one confirm this? Wondering if it would be a good idea to put drains on these to maybe open after a run so the oil can't seep by guides and maybe reduce leaks.
Jerry

[rwahlgren]

Some R-4360's didn't have lower rocker box drains either. And I thought the same thing you did. Another place for oil to leak and cause a hydraulic lock when sitting for extended periods. If you add drains a scavenge pump would be needed to make it work. Just going back to the sump wouldn't accomplish much. Are there plugged holes in the rocker boxes for drains?

[jwilcox]

I'm planning to give the valve cover drain idea a try, if these were normally aspirated engines and had vacuum on the intake I think a large amount of oil would be pulled by the intake guides but being supercharged probably changes that, does that sound correct? Still when shut down with hot oil it seems some must get by the guides and also leak externally if not sealed up properly. My plan is to have them plumbed to a common drain that can be opened after shut down and closed while running. A container would catch the oil and every few runs be dumped back into the main tank, a bit messy probably but worth it if it helped avoid lock and might clear up the running (smoke) a little sooner on start. I have plenty of spare valve covers and they are thick enough to tap for a 1/8 pipe thread so may just try a nipple in each one and see how it goes.

[rwahlgren]

All large radial engines I know of, had a supercharger and some have a turbocharger as well. The impeller also helps distribute the fuel air charge better. It would be nice to figure out how to plumb it without goofing up the rare parts. Even if you have to fabricate rocker box covers. The rocker box castings may already be drilled and tapped for drains.

[rkammlott]

Before I run my 4360 I have to drain the intake tubes . the lower cylinders collect a lot of oil. My engine has about 5 or 6 drain plugs on the tubes. my supercharger has a big one also. I never get oil into that one.if I flood the engine with a bad start I have to drain the gas. I collect about 2 qt oil in the engine if it sits for more than a week.I never had a problem with the rocker covers filling.

[jwilcox]

Apparently some if not all the 2600s that were used here had drains on the lower intake tubes. My question is where does the oil in the intake tubes come from? It surely cant be from the intake/supercharger side, if so it seems the oil consumption would be very high. I'm thinking it is hot on shut down and with the rocker covers and push rod tubes full on the lower cylinders the oil seeps past the intake guide and collects in the intake tube. Some may also get past the piston to an open intake valve. Could be I'm giving this too much thought and the intake tube drains are all that is necessary, after all these engines have run for over 70 years. Thanks for the reply's, much appreciated.

[rkammlott]

I think the oil is coming from the cylinder through a open intake valve. when I had individual stack exhaust , some of the cylinders leaked oil from the exhaust also. I think youll be fine as long as you check for hydraulic lock before each run.

[rwahlgren]

-59 B has lower intake manifold drains to drain off accumulated oil, there are lines connected to the drains to constantly drain off the oil.
http://www.enginehistory.org/Museums/SeattleMoF/cyl%20and%20drain.jpg
The rocker boxes are full of oil and are a possible source of oil, and past rings while sitting.