R3 Valve Covers

[Leo B]

I couldn't find if this issue has been discussed before. I noticed that the R3 valve cover has two breathers in both.
Is there a particular reason for that? Heat? More breathering flow? Were the dual breather covers only on the R3?

[Dwight FitzSimons]

R3 & R4 rocker (valve) covers have two breather caps per cover.  I assume the reason there are two is to evacuate the increased blowby gases that the R3/R4 engines produce due to their increased piston-to-cylinder-wall clearances.  The larger clearances throughout the engine reduce frictional losses.  (One result of this is that an R3 engine will rev up more quickly than an R2.) 

Note that the diameter of the breather tubes on an R3 or R4 rocker cover is not the same as an R1 or R2 (or 259 or 289).  It is larger, probably an eighth of an inch larger in diameter.

The larger "open" breather caps used on R3/R4 engines are also used on earlier six cylinder engines.

--Dwight

Edited June 24, 2023 by Dwight FitzSimons

[Leo B]

Thanks for the good answer. 👍

Edited June 23, 2023 by Leo B

[Nelson]

Leo. I also read, back in the day, the additional breathers in valve covers and pan was to allow oil return to the pan without fighting windage headed toward the valve covers. This is more true with the pan breather as the ones in the valve covers would seem to have a counter productive result to some degree. I also know high pressure in the oil pan will rob  hp as your combustion pressure to crankcase delta is reduced. Some drag race cars actually pump crankcase pressure out to maximize power. 

[Leo B]

Thank you Nelson. I just read this from https://www.curbsideclassic.com/automotive-histories/engine-history-the-studebaker-v8/

Is this related?
There was a tendency of the oiling system to send too much oil to the rocker arm shafts as they wore, which could lead to oil starvation on the bottom end and low oil pressure problems. This rocker arm shaft wear was often the result of extended higher RPM usage, like high speed highway driving. The engine would pump too much oil to the top end of the motor and it couldn’t drain back to the pan fast enough. In mid-1961 Studebaker made some modifications to attempt to correct this problem. They used a smaller oil passage in the rocker arm shafts to restrict the oil to the top end and a large drain hole in the cylinder heads to get it back to the pan more quickly.

 

[Nelson]

Yes, too much oil in the valve covers and not enough in the pan. They also added windage trays in the pan to help oil get to the pump instead of frothing it up with the crankshaft. A lot of simple but effective ways to keep oil under control at high rpm’s.