Camshaft Tolerances

I just got my camshafts out tonight and doing a preliminary inspection revealed a couple of questionable circumstances:

The cams have the following numbers:
1-3(L) 930.105.147.7R
4-6(R) 930.105.148.7R

I was suprised to see that the housing that holds the cams do not have liner bearings (Like the crankshaft) The clearances are .002 inches throughout on both cams.The cam size is 1.926 on all of the cam journals. But if I read the small spec book I have they should be 48.926 - 48.942mm (1.908 - 1.909 inches) Did I convert wrong ?

I think it's 2.54 cm per inch.

David,

It looks to me like your cam is within spec: 48.942 / 25.4 = 1.9268 "

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Warren Hall
1973 911S Targa

Thanks guys. Thats what I get for using the wrong conversion.

I just noticed a very small pit on the #4 intake cam lobe. It is right at the edge of where the rocker arm would ride( Based on the wear pattern). If I replace the cam would it be worth upgrading or just replace in kind? If I change one cam should I change both? The original plan was to pretty much stay stock.

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78 911SC

David,

How wide is the pit? If we are talking 0.5 mm or so, I don't think you need to worry about replacing that cam! You could, of course get them reground to 964 cam specs, and a worthwhile boost in power.

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Warren Hall
1973 911S Targa

Thanks again Warren.. The pit is much less than (.5mm) I'm unfamiliar with the 964 cams and what other mods would be required. Where can I find out more??

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78 911SC

David,

Try contacting WebCam ... www.webcaminc.com

i don't believe any other modifications are required, though SSI's or '65-'74 heat exchangers would help quite a bit! The 964 cams are considered to be the 'hottest' cam that can be used with CIS fuel injection, which are sensitive to intake pulsations or reversion caused by more aggresive cams.

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Warren Hall
1973 911S Targa