Cams and Cam Housings

[chris_seven]

As we are just about to start machining our forged rockers and we are also looking at buying some cams and I have been trying to figure out the various types irrespective of profiles so we can sort out blanks.

I think that there were the following types:

A: 3 bearing, 47mm dia, Centre Lube, External threads. Very Early 911 and 906 ?

B: 3 Bearing, 47mm dia, Spray Lube, External Threads 65-68. 911 and may be 74 and 75 2.7 litre CIS

C: 3 Bearing, 47mm dia, Spray Lube, External Threads, MFI Drive on Left Hand
Cam, MFI Engine 1969 to 1973

D: 4 bearing, 47mm dia, Centre Lube. External Threads, MFI Drive on Left Hand
Cam - 2.8 RSR

E: 4 Bearing 49mm dia, Spray Lube, External Threads 1976-1979

F: 4 Bearing 49mm dia, Spary Lube, Internal Threads `1980 -1989

I am also keen to understand the purpose of the lug in the casting on a Left Hand 1969 911S cam - anyone know?



I also have an odd set of cam housings dated 1974 and used on a 2.7 CIS engine.

The housings appear to have 4 bearings 47mm dia but only 3 are drilled for the spray bar. I am confident that there are 4 journals.

The cams were 3 bearing, external thread type.

We took these housing off a 1974 2.7 with a K Jetronic.

If we drilled out the 4th spray bar hole could we fit RSR small journal cams?

I would be grateful if someone would point out the mistakes I am sure to have made.

[Spenny_b]

Chris, can't answer the more in depth historical stuff for you, but w.r.t. that "?" in the photo, I know that on the Vauxhall cams in something like my XE "Redtop", they have very similar looking square sections, which we use simply to be able to counter-hold the cam when tightening up the pulley bolt, and also to rotate the cam when timing-up with vernier pulleys.

But that wouldn't explain why only the LH cam has this?

[ajwans]

Originally Posted by chris_seven

I also have an odd set of cam housings dated 1974 and used on a 2.7 CIS engine.

The housings appear to have 4 bearings 47mm dia but only 3 are drilled for the spray bar. I am confident that there are 4 journals.

The cams were 3 bearing, external thread type.

We took these housing off a 1974 2.7 with a K Jetronic.

If we drilled out the 4th spray bar hole could we fit RSR small journal cams?

I would be grateful if someone would point out the mistakes I am sure to have made.

Does the casting number on the housings end with "1R". I think what you have there is a set of the transition housings which are neat because they can be used with early cams and also with 47mm 4-bearing cams.

andy

[chris_seven]

Originally Posted by ajwans

Does the casting number on the housings end with "1R". I think what you have there is a set of the transition housings which are neat because they can be used with early cams and also with 47mm 4-bearing cams.

andy

Andy,

Yes it does end in 1R and this is what I had hoped.

[tom1394racing]

Chris

I believe the 4 bearing 47 mm journal towers are the RSR type. The 4th journal was machined, but no lube holes added, because the RSR used center lube cams.

I have a couple of sets of these as well.

[Flieger]

I think the 1977 911S had those housings with the 4th bearing that was cast but not machined.

[tom1394racing]

Originally Posted by Flieger

I think the 1977 911S had those housings with the 4th bearing that was cast but not machined.

This is true...These were made in 76 and 77 and are the same casting as the "RSR" tower with the machined 4th bearing journal..