R3 Item!

[mfg]

What item does a 'B' series Studebaker Avanti R3 engine have that the earlier 'A' series R3's did not.......?........

1) Dual Breather Rocker Covers.......2) 276' Cam.......3) Fifth Crankcase Breather on oil Pan Vent Tube.....4) Aluminum Carb Enclosure....or.....5) 'A' series R3's had items 1 thru 4

[1963r2]

I think number 3.

pb

[mfg]

41 minutes ago, 1963r2 said:

I think number 3.

pb

Good try but no, the 'A' series R3's had the fifth breather.

[VtMike]

My bet is that the A series didn't have the milder 276 cam.  They have been described as hand built racing engines, and their job was to produce a lot of power and promote the performance image at Bonneville and in early magazine road tests.  So there likely would have been much less concern over whether they had street manners that non-racers would expect.  Second, I think Jack Vines wrote recently that the Stude factory refused to use one of the cams in the factory R3s . . . maybe because it was too wild?  So that may have been related to the intro of the milder 276 cam?  Anyway, that's my wild guess.

[mfg]

15 minutes ago, VtMike said:

My bet is that the A series didn't have the milder 276 cam.  They have been described as hand built racing engines, and their job was to produce a lot of power and promote the performance image at Bonneville and in early magazine road tests.  So there likely would have been much less concern over whether they had street manners that non-racers would expect.  Second, I think Jack Vines wrote recently that the Stude factory refused to use one of the cams in the factory R3s . . . maybe because it was too wild?  So that may have been related to the intro of the milder 276 cam?  Anyway, that's my wild guess.

What you wrote makes good sense, however, the "A" R3's (well, I should say the one that I'm basing this trivia question on) were indeed equipped with the 276' camshaft.

[mfg]

All through here?

[mfg]

UNCLE?

[lschuc]

Answer #5 is correct.  All A and B series had all those items.   But one BIG difference is that the A-series engines were 299ci displacement, and B-series engines were 304.5 cid.

Working with a standard R2 engine as its base, the first prototype R3 engines displaced 299.5 c.i. These are generally referred to as "A" engines and were used in the first record setting Bonneville Salt Flats runs. When one of these engines pushed an Avanti to 170.78 mph it officially became the Worlds Fastest Production Car. 

The "production" R3 engine was bored out further to 304.5 c.i. and are stamped as "B" engines. Standard R3 camshaft was 276 degree with 288 degree optional.

See the attached photo of the #9 Bonneville Avanti that shows the dual breathers on the valve covers, and a breather cap on the oil pan breather tube.

 

 

[saddletramp]

Does anyone know what the rearend ratio was on the Bonneville Avanti??

[VtMike]

I think I read somewhere that one of the Bonneville Studes tried a ratio of 2.9ish but settled on 3.00.

[mfg]

And lschuc is CORRECT here! (#5).......Thanks for posting that photo!