Wacky Camshaft Part Number Confusion...
 

Okay, Warren's favorite topic. I'm compiling data for the Appendix of the engine book. I've looked at Frere's book, and the numbers that he has do not match any of the nine Porsche spec books. These are the intake/exhaust open/close numbers.

I don't understand where he got these numbers from, and how everyone of the spec books can be wrong. Or am I overlooking something obvious?

-Wayne

Wayne....
Check the way he compiled the numbers.
Most cams are checked at the .050" lift point.
However...I have seen numbers for some manufacturers that must be at zero lift....hence the numbers are larger even though the cams are the same.
Bob

That's initially what I thought, but there are no footnotes on the table.

???

-Wayne

Sorry I can't help with your question, but I have another one...

I have 2 2.4S engines, a 72 and a 73, and both of the right cams have an E part number. At first I thought it may be because the cam was reground to S spec, but after I acquired the second engine I am starting to doubt the spec book. Both cams measured to S spec. Anybody have any insight?

Thanks!
BK

The number is 901.105.110

Unfortunately, I don't think that the number that is stamped on the camshaft is necessarily the same as the part number. Kindof like the case casting numbers are not the case part numbers.

-Wayne

Wayne,

It is standard in the German automotive industry to use timing specs at a lift of 1.00 mm. I have seen references to that method in VW and Porsche cam data dating back to 1961. Long before US mfrs started using the 0.050" method ... just once it would have been nice for the USA to use methods and data compatible with european publications in the industry! Like it makes a big deal ... 0.040" vs 0.050" wouldn't have mattered a bit!

Bruce Anderson just shot me back some useful info:

Hi Wayne,

There is a problem with something with the cam timing specs in one of the
books. It is the 911 E-C engines Type 911/01 and 911/04. Specs should be the
same as 901/09 and 901/11. The rest all seem to work if you use 1 mm as a
checking height, then you seem to come up with pretty much the same numbers
as in the spec books. I am not sure what sort of a measurement scheme they
were using when Paul got his numbers.

Bruce

also:

Hi Wayne,

Actually there is only one E cam, they just time it a little different on the
2.4 cars. This is actually the same grind as what we call the “Solex Cams”.

Bruce

Time for battle of the experts!

-Wayne

The part no. is on the camshaft.

BK911,
Your right side cam (901.105.110) is an E cam. Apparently, it has been reground to S spec. Can't say why both your S engines have this same configuration.

The numbers for '67-68 S cams are:
901.105.123 (left)
901.105.124 (right)

The numbers for '69-73 S cams are:
901.105.183 (left)
901.105.168 (right)

Wayne,
I would cite tech specs from Porsche rather than from a secondary publication, even a Frere pub.

Sherwood Lee
http://members.rennlist.org/911pcars

I don't think that the casting number on the side of the billet actually reflects the cam grind on the early cars. I have seen 'E' cams with a completely wacky part number on the side that doesn't correspond to anything...

-Wayne

Wayne,

Looking back in the text of chapter 3, Frere says data taken with 0.1 mm valve clearance ... rather than 1 mm ... so it would appear that his data is of the type 'advertised duration' ... used in hotrod publications! That would explain 'bigger' numbers than the spec book!

Hmm, I still can't find reference to either Frere's method of calculation, or the factory's method either. Anyone have a Porsche document they can point me to?

I checked the back of Ch3, and I can't find it (sixth edition).

[edit - okay just found it in the appendix]

That would make sense to me, but I'd still like to reference it in print...

-Wayne

Revitalizing this old thread: I have an original 1973 2.4S engine (never opened, I'm 99% sure) that has the 901.105.183.0R (S) number on the left one and the 901.105.110.1R (E) number on the right shaft. In rebuilding, we discovered this, but now I read that it's (relatively) common that the right S-cams had E numbers? Any more info on that? thnx. Tom

For an ultimate concours disclosure :) or FYI?

If for rebuilding info, can compare the intake/exhaust lobes of each cam to confirm they're compatible.

S

thanks. My point is that the factory used cast E-cams with S-profiles on the right shafts, seems to be on '72/'73 engines. Does anyone have more info on that?
Profiles of my both cams match; Part.numbers on the shafts don't. How come? Nobody did regrind the cam after factory delivery...

Thback, I have the same experience as you with 2 motors.
One 73 RS motor and on 72S motor.
I didn't pull the motors apart so I thought I had an E-Cam as replacements on both.
Bought a set of original "S" re-ground cams from Henry Schmidt and guess what? Same part number. He swore they were the original cams out of an S motor.

I have access to a cam doctor so someday when I have absolutely nothing else to do I will verify the grind.
Visually and a little measuring, I am 90% sure they are an S grind with what we have been led to believe is a "E" part number.

thanks for verifying and confirming; I measured the grind and it was an S-grind. I know of some others that had (at least) and "S" on the cam side; However, mine just had " 01" on de side. I guess the factory needed S-grinds urgently and had some E-castings left .. :confused:

There are plenty of S grinds with Solex casting numbers out there as well