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-   -   Are cam journals polished during a regrind? (http://forums.pelicanparts.com/911-engine-rebuilding-forum/1035070-cam-journals-polished-during-regrind.html)

bpu699 07-18-2019 01:50 PM

Are cam journals polished during a regrind?
 
Just curious. Got my cams back from webcams. They look great.

Of interest, one cam spun really easily before regrind, one spun ok, but with minuscule resistance...

Was planning to retorque cam towers and all...

Now, both spin freely...

Wasn’t expecting that? On the one hand it’s great. On the other hand, doesn’t polishing increase clearances?

KTL 07-29-2019 08:10 AM

Bo,

When I had my damaged cams repaired by Webcam, they sent them out to have the journals repaired. The lobes were previously hardwelded by Webcam (I sent them good used cores for a 120/104 profile) and I assume the journals were left as is. Then when I had an oiling problem, the bearing debris thrashed the journal surfaces. So they sent them out for repair.

Regarding the spin resistance, I suspect it's more due to the housings and not the cam itself. The housings apparently tend to twist and that affects the bore alignment.

Webcam is GREAT to work with. They turn things around in the time promised and their time is not lengthy at all.

bpu699 07-29-2019 11:50 AM

Quote:

Originally Posted by KTL (Post 10539916)
Bo,

When I had my damaged cams repaired by Webcam, they sent them out to have the journals repaired. The lobes were previously hardwelded by Webcam (I sent them good used cores for a 120/104 profile) and I assume the journals were left as is. Then when I had an oiling problem, the bearing debris thrashed the journal surfaces. So they sent them out for repair.

Regarding the spin resistance, I suspect it's more due to the housings and not the cam itself. The housings apparently tend to twist and that affects the bore alignment.

Webcam is GREAT to work with. They turn things around in the time promised and their time is not lengthy at all.

Yep, cams look great. Whatever black coating they coat them with is very fragile... seems to almost flake off with minimal contact...

Not sure what they did to the cams, but they both spin great now, with the same minimum resistance...

Its very satisfying to FINALLY get to this point in this eternal project...

stownsen914 07-29-2019 03:33 PM

As mentioned, any machining done anywhere in the stack can impact flatness of the surface the the cam towers bolt to. Ive heard that even the torque sequence can impact free turning cams vs having resistance. Sounds like you should be good to go!


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