Camshaft query

[AndrewSlater]

As part of my engine rebuild of a 1974 911 CIS 911/92 engine I have spotted my engine is fitted with a
911 105 141 00 left cam and a 911 105 144 00 right cam.

Am I correct in thinking that the 144 cam is definitely the wrong part?
From the PET guide and the Dempsey book I believe my right cam should be a 142 part.

Assuming that the 144 is the wrong part for the car is it feasible that the 144 has previously been reground to the 142 profile ( or would this be impossible from the original profile ).

Also any info on what the difference between the two profiles is would be helpful as I could make an attempt to measure the right cam.

This might explain why the car was put into storage in the late eighties after some form of engine rebuild. I'm guessing it wouldn't have run well with the wrong cam.

As always any help and suggestions much welcome.

Finally if anyone has a good 911 105 142 00 camshaft then please drop me a PM.

Thanks
Andrew

[Lightweight_911]

Andrew - the valve timing for those 2 cams is quite different:

'142' timing -

Inlet opens 1 deg ATDC, closes 35 deg ABDC
Ex opens 20 deg BBDC, closes 7 deg BTDC

'144' timing -

Inlet opens 6 deg ATDC, closes 50 deg ABDC
Ex opens 24 deg BBDC, closes 2 deg BTDC

I think it's highly unlikely to have been reprofiled


.

[AndrewSlater]

Thanks for the info Andy - much appreciated.

I spotted a couple of posts on pelican that suggested they were interchangeable but I was sceptical.
Makes me more convinced that this was probably why the car was taken off the road back in the 80s after a non successful engine rebuild.

I can't believe I didn't check the part numbers earlier, have checked everything else on the build.
Just glad I spotted it now as it wouldn't have been much fun to diagnose later down the line.

I've already got an offer of a '142' cam so I'm guessing that's the way to go.
As always thanks for the help.
Andrew

[sladey]

Yep good spot there - saved yourself hours of heartache later

[AndrewSlater]

Apologies for more questions but do you know whether the 144 camshaft has reduced lift over the 142?

The reason I ask is that I have now hit another low (read:show stopper) in the engine rebuild ( see my restoration thread ).

In summary I have fitted the new camshaft to the right bank, but after timing I am getting interference between the exhaust valves and the pistons. The left bank is good with 2mm clearance on both inlet and outlets. The right bank has issues at 0mm clearance.

The engine turned fine before the rebuild so wondering where I have lost 2mm of clearance on the right bank.

The machinists tell me the case bores were skimmed 0.3mm, so I have gone from a 0.25mm to 0.5mm cylinder gasket to compensate.

The only other thing that I have changed is the right camshaft, and the heads have been reworked.

One thought was that the 144 camshaft might have been less aggressive than the 142. ( Yes I am clutching at straws ). Or my right hand cam timing is out ( and yes I have checked it many times and it is 0.8mm at TDC with rocker gap set to 0.1mm ).

I'm at a bit of a loss as to where to begin.
As always any suggestion much appreciated.
Thanks
Andrew