3.0 Cam, 3 vs 4 journal surprise
 

I think I know the answer but I will throw it out for comments by the experts.

Redoing my '77 3.0 top end due to broken rings, 4 out of 6. Anyway, while it's apart, I decide to "upgrade" to a Web 964 cam but today I learned I have (3) journal 47mm towers not the (4) journal 49mm that Webb thought I had. I also just today learned that early 3.0's had 3 bearings and then later had 4, after the release of the 930. I guess they could save machining or something.

So do I:
A) Have Web send me a 4 journal 47mm 964 cam and run it in the 3 journal tower?
B) Use the 49MM cam and either buy a 49MM tower or machine mine to 49MM?

From what I have read, but never seen, I can run the 4 journal in the 3 tower.
Appreciate your comments. Thanks

I run 964 cams, WEB 120/104 grind and they do have the bigger journals.
Plus the nose has to be welded, ground and the woodruff key slot cut in to use the early cam sprocket. They also need the PS and scavenge pump drives cut off for earlier engines.
You could use the 964 sprockets, but the timing tools are around $1000 and you would've cut off the timing tool notch with the PS drive.

Just get used 4 journal towers, cheaper than new cams and stronger than 3 journal.

If you grind the 4 joirnals to fit the 3 journal carriers the lobes on the cams won’t permit installation.
The vernier chain drives are all the same, 901 part numbers but on a real 964 cam right side you need to cut off the power steering drive so you clear the oil cooler.
Bruce

No they are not, the 964 cam nose hub and sprocket are different and are not interchangeable.

I should know as I've modified more than a few 964 sets to accept the early 901 sprocket.
The 964 cams take sprocket part# 993 105 546 00 and 02, it has no woodruff key, it doesn't use the 901 sprocket adjuster hub and pin, I believe it has a different big washer as well.
The 901 sprocket hole is too big for the stepped nose on the 964 cam, that's why the 964 cam nose has to be welded, ground and have a woodruff key slot cut to use a 901 sprocket assembly.

Maybe some of the early 964 cams had the 901 sprocket, I admit that wouldn't surprise me knowing Porsche.

Web Cam has a 47mm 964 cam that can be used in the 3 journal.

My only other choice is stay with the 2.7 911S cam that was in it. THe darn thing was fun even with bad leak down in 4 of the 6 Cylinders.

I have also seen a post that the earl "S" cam with Euro 9.8CR pistons and carbs works really good.

Mark, you’re referring to the 993 cams without the key way.
I just installed 964 cams into a 3.2 using the 901 chain drive vernier after cutting off the PS drive.
Bruce

Maybe I'm wrong and I have 993 cams, just figured the cams I have were 964 because that's the number cast into them.
964 246 which is odd as they usually have at least 9 digits.