Engine: Note on S.I. deep breather caps/filters

[Mike Van Veghten]

A note for anyone buying these "extremly" HIGH cost caps.

As they come out of the box...they are mostly usless as a "breather cap". And, they will only fit the rocker covers. I tried mine on the iron breather tube, the short alum. breather and the long alum. (pot metal) tube and it didn't fit any of them.

The two tiny little .128" (or so) holes in them will not even support human life..!
To make them work as designed, you will have to drill/grind as much of the "inner" cap away as you can. Just remember to not remove the material adjacent to the spring. Also use grease on the drill to hold as many chips as you can....then clean the cap as well as you can.

The design has changed, along with I assume the manufacturer, and that manufacturer/designer, knows nothing about air transfer.

Just a word to the wise....DO NOT expect actual "breathing" to take place with these caps until modified.

Mike

[skyway]

Aw come on Mike, you don't actually plan to drive with those caps do you?

[SN-60]

These caps must be for 'closed crankcase' Studebakers!

[StudeRich]

All PCV equipped Studes. had these restricted Oil breather Caps as Mike describes, these are "open" systems as used on all 1963's and the South Bend built 1964 models.
The aftermarket chrome Caps are exact copies of the OEM Red painted Caps and the "R" Series chrome Caps.

The Hamilton '64's with the "upper" pollution control closed system, have a Cap with no breather holes whatsoever on the left and a Cap with a hose fitting for the air cleaner hose on the right.

[Mike Van Veghten]

StudeRich, SN-60 -

Well...not so quick...!
I do have an OLD...cap. No idea if it is "original"..old, but it's been around a very LONG time.
The design of that one is correct...as far as a "breather" goes. It's got a "little" of the STP sticker still on it and is of the deep design.

Plus...what use are they if they don't.."breath" ? Might as well just seal up the holes in the rocker covers/pan "breather" tubes.

Or...was this the first form of introducing vacuum into the crankcase thru the carburetor ? Modern vacuum systems do have valves somewhere in the system (normally on a rocker cover) to limit the actual vacuum in the engine.
I doubt this though, since once the throttle is open quickly and fully...vacuum in the system will drop to zero (near zero)...eliminating any good that would have come from the vacuum....just when you need crankcase vacuum the most.

And skyway -

Sure..they fit much better thAn current, modern short style caps. At least they don't move around because of the loose fit..!
Just gotta make them work as breathers..!

Mike

[JoeHall]

All PCV equipped Studes. had these restricted Oil breather Caps as Mike describes, these are "open" systems as used on all 1963's and the South Bend built 1964 models.
The aftermarket chrome Caps are exact copies of the OEM Red painted Caps and the "R" Series chrome Caps.

The Hamilton '64's with the "upper" pollution control closed system, have a Cap with no breather holes whatsoever on the left and a Cap with a hose fitting for the air cleaner hose on the right.

I have had several full flow 259/289s, from California to Kentucky, and have seen a kajillion orange breather caps, still with the original STP stickers on them. But I have never seen even ONE that did not have 10-12 breather holes in bottom side, around the outer edge, about 5/16" in diameter.

[Mike]

I have had several full flow 259/289s, from California to Kentucky, and have seen a kajillion orange breather caps, still with the original STP stickers on them. But I have never seen even ONE that did not have 10-12 breather holes in bottom side, around the outer edge, about 5/16" in diameter.

The restricted caps have the large holes around the rim. Inside, next to the spring, there are the two small holes mentioned.
Mike M.

[63 R2 Hawk]

I seem to remember something I read years ago about R2 cars having different, special restricted breather caps. R2s have both the air cleaner intake vacuum port and the vac port with check valve at the base of the AFB which is ported to the dipstick "hole" to provide venting. Due to CRS, I don't remember where I read that......

[Bob Langer]

This is from the Avanti shop manual explaining how the oil filler caps work with the positive crankcase ventilation system.

[StudeRich]

I have had several full flow 259/289s, from California to Kentucky, and have seen a kajillion orange breather caps, still with the original STP stickers on them. But I have never seen even ONE that did not have 10-12 breather holes in bottom side, around the outer edge, about 5/16" in diameter.

You are correct Joe about the outside Air Holes in the Caps.
AGAIN: "ALL Studes. except Calif. & New York or possibly ALL Hamilton '64 1/2, '65 and '66's have the open, filtered Oil Cap you describe, BUT '63 & South Bend '64's have the two very small restrictor holes inside" as Mike M described, just like the Avanti System that Bob Langer posted about.

So NOW, is everyone on the same page and CLEAR now? I hope so because I am sorry, I can not describe it any better.

[WCP]

Only the R3 caps were open inside (without the 2 metering holes) and are apparently are slightly larger in "bore" diameter.

[Flashback]

Someone please post a good engine picture or a shop manual picture, showing a 63 Avanti R-2 pcv system. The breather tube that comes from the oil pan on the right side, just has a 5/8 or 3/4 opening in the top right? No breather cap? Is the wye mentioned in this line? I thought this large line went to the air cleaner. Is there any other fittings in the big tube other than the oil dip stick? How big is the big tube, and does it just drop down the the air cleaner hose size at the top? Is the pvc valve and check valve two different animals on the R-2?

[Hawklover]

Rich, I have had my Avanti since 1966, and the caps on the rocker covers have all the holes around the inside, plus the two tiny holes adjacent to the spring at the bottom..........what does this mean???

You are correct Joe about the outside Air Holes in the Caps.
AGAIN: "ALL Studes. except Calif. & New York or possibly ALL Hamilton '64 1/2, '65 and '66's have the open, filtered Oil Cap you describe, BUT '63 & South Bend '64's have the two very small restrictor holes inside" as Mike M described, just like the Avanti System that Bob Langer posted about.

So NOW, is everyone on the same page and CLEAR now? I hope so because I am sorry, I can not describe it any better.