85euro928

I need some advice on what to do with my cams (sorry if this is long). A little history; the PO had a timing belt failure about a year before I purchased the car and I’m guessing they didn’t torque the drivers’ side cam gear correctly as it came loose and ruined the cam (see my avatar). The cam I need to replace has a PN of 928 105 188 with a 212 stamped on the end which makes no sense to me as the PET shows 928 105 188 as the PN for a M28.11/12 and 928 105 212 as the PN for a M28.21/22? My block is stamped with M28.21. The problem I have is that I purchased a cam with PN 928 105 188 which only has a small triangle stamped into the end of the shaft, no other number. In the first picture my 1-4 cam is on the left, my 5-8 cam is in the middle, and the 5-8 cam I just purchased is on the right. If you look closely at the pictures you can see that the middle cam and the right cam lobes have different profiles. I’ve measured the lift and they’re virtually the same. The cam I purchased appears to be from an ’83 M28.11/12.
My question is, can I “easily” have the ’83 cam ground to match my cam, or can I have my 1-4 cam ground to match the ‘83 cam? Any advice would be appreciated. Thanks.


Pic 1


Pic 2

IcemanG17

the early euro S cam has the same lift, but less duration than the later Euro S LH cams you have...the cams you need are the 211-212 stamped cams.... Contact 928intl, they might have a set for you..but they typically sell as a set...

You could use the older Euro S cams...but I would change them both so they match...but you will loose some HP too....

85euro928

Iceman,
I guess grinding the '83 cam to match the '85 cam is out of the question then? From the naked eye it looks like it should be possible as long as the lobe seperations were the same. I was hoping someone here might be able to tell me if it could be done and suggest someone here who could do it.

123quattro

1. I think your original cam could be fixed by a competent machine shop.
2. I would just put the new cam in and run it as is.

If you regrind the cam, you'll have a ton of money into it for maybe a net difference of 5hp.

Lizard928

If Brian is correct on those figures, which would make sense.
It does appear as though the cam on the far right has slightly more duration than your cam in the center.
This means that it is more likely to be the later camshaft.......

With the slight addition of a tick more duration, I doubt it will make any difference.
The LSA appear to be identical, and if not identical, then close enough that you will not see a difference.
This coupled with the fact that the stock 16V cars do not have adjustable camshafts like the 32V means that you should see zero issue with running that cam.

IIRC from the manual, the intake has 2 deg less duration on the intake, and the exhaust closer to 3-4.

85euro928

John, I already took the cam to a local well-respected machinist who said that if the cam wasn't cast he could just cut the cracked end off then make up and weld on a new piece so I don't believe that fixing my cam is an option

Colin, Yea I'm not the kind of person who could put two mismatched cams into my engine and then sleep at night. Even if they are real close spec wise. Considering how much time and $ I've sunk into the car already I think it's worth doing it right.

On another note in doing some searches on the forum I notice that some people may have experimented with reducing the cam base by 1mm. If I need to get one cam ground I might as well get them both done. Anyone every find out if there was an oiling problem with the lifter when doing this? What about valve interference? I think I remember Mark K noting that there was about 3mm of clearance at TDC, anyone have any problems with this when shaving the cam base?