Can anyone identify these factory race camshafts?

[blue72s]

Factory 4-bearing center-lube camshafts

Casting numbers
911-105-155-00
911-105-156-00

I still don't know what is the diameter of the bearing journals but does anyone recognize those numbers above? What spec/model are they for?


Thanks in advance.

[Classic 911]

Following


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[gled49]

All 4 bearing center oil race cams were small journal. Don’t know if the casting numbers are part numbers. By part number, not RSR or 935 by my info. What size are the cam nuts and the thread pitch. Could be home made?

[blue72s]

These look factory to me. I don't know the cam nut size or thread pitch as of yet.

[Flat6pac]

Fine thread 42 mm nut size, on the couple I built.
Bruce

[blue72s]

So, nobody knows what model the cams are for?

906?
ST?
2.8 RSR?
3.0 RSR?
SCRS?
Carb or MFI?
Sprint or Endurance?

One of the clues is the first three digits of the casting number:
"901" tends to be early (usually pre-69) whereas "911" is probably after that. But don't take my word for it.

[gled49]

3.0 RSR in 74 was first 4 bearing race cams. I ruled out all 3 bearing cams, 906, R, ST, 2.8. Those look like fine thread, recessed end factory cams. That’s all I got.

[dannobee]

All you have are the casting numbers. Any other info is normally stamped on the end of the cams, but even then, it's no guarantee of anything because they could have been reground.

If you really want to know what you have, get out a dial indicator, a couple of rocker arms, and a degree wheel and measure them. The short cut would be to use a cam carrier and a rocker arm and measure valve lift, then compare to a chart of the race cams. But even then, you still wouldn't know the duration without using a degree wheel.

Or, if you happen to know an automotive machinist with a "cam doctor," he can put them in some V-blocks and tell you what you have.

[safe]

Originally Posted by dannobee

All you have are the casting numbers. Any other info is normally stamped on the end of the cams, but even then, it's no guarantee of anything because they could have been reground.

If you really want to know what you have, get out a dial indicator, a couple of rocker arms, and a degree wheel and measure them. The short cut would be to use a cam carrier and a rocker arm and measure valve lift, then compare to a chart of the race cams. But even then, you still wouldn't know the duration without using a degree wheel.

Or, if you happen to know an automotive machinist with a "cam doctor," he can put them in some V-blocks and tell you what you have.

+1
The cast number are just a number for the blanks before grinding.

[Travis Neff]

Part number for a blank, uncut cam? I found this.

https://www.early911sregistry.org/forums/showthread.php?80721-FS-Porsche-Camshafts

[blue72s]

Originally Posted by Travis Neff

Part number for a blank, uncut cam? I found this.

https://www.early911sregistry.org/forums/showthread.php?80721-FS-Porsche-Camshafts

Thanks for the link. I did not see that before.

Thanks everyone.

[icarp]

If they are real "FACTORY RACE CAMS " the numbers will be missleading on purpose ,
All info is set to mix up the user , factory privilage eyes only. It's in code

VS JUST CUSTOMER RACE CAMS


Ian

[MoreGAS]

Measure the journal diameter to narrow it down, that is about as easy as wanting info gets.
Then if you still strike out, send them to Web and ask them to evaluate them on the Cam Dr (see exact open and closing times for both sides, total lift etc) and learn what they are exactly, in case they have been modified. This will tell you what lobe centers they are on also, in case folks desired a changed.