time to time the cams......

rcwaldo · 01-30-2002, 06:03 PM

Hello all. My rebuild project is coming along on the 2.7. I need to time the cams. I am used to Chevy's where I use a LARGE degree wheel and cam card (cam card comes with new cam).

Can anyone help me out with cam specs? In all the reading material that I have, I cannot find any specs for my cams. This is a 1974 2.7 from a 911, not a 911S. The cam part numbers:

Right side: 911.105.144.0R
Left side : 911.105.143.0R

Can anyone help me out? Also, any tips to avoid mistakes?

thanks a bunch!

Chris

makaio · 01-30-2002, 06:40 PM

I can't help, but just wanted to say good luck!

Fishcop · Fishcop's Garage

You'll need a dial guage with correct mounting arm, the big crows-foot spanner and the "other" tool that holds the cam as you turn the big nut. I watched my mechanic do it a while ago and was very impressed! Not something I'd like to do alone. Bruce Anderson's book goes through it fairly closely, I'd advise you have a look at that section.

Big good luck!

Early_S_Man · 01-30-2002, 10:00 PM

Chris,

Per the '74 spec book, with those cams the TDC overlap intake lift value is 0.40 mm to 0.54 mm, with 0.50 mm being the 'desired' adjustment value. You need to get the values for left and right banks as close together as possible ... the same, or within 0.001" or 0.01 mm.

rcwaldo · 01-30-2002, 10:31 PM

thanks guys for the help. I have all of the measuring equipment, just not the specs.

Anyone verify what cams that I have? Please see original post for the p/n's. I guess my question is, are these 2.7 CIS S cams or just 2.7 CIS cams?

I appreciate it greatly!!!!!!

Chris

Early_S_Man · 01-30-2002, 11:00 PM

Chris,

Spec book says '74 CIS 911S/Carrera cams!

ChrisBennet · ChrisBennet's Garage

Chris,
In order for your cam measurements to mean anything they must be repeatable. You should be able to get the same reading +-.01mm again and again. I've found the following things to have an effect on repeatability:
Proper chain tension: You can use mechanical tensioners or a special tool to keep the chain taught. A hydraulic tensioner doesn't push hard enough.
Cam lube: If you have too much lube on the cam lobes the rocker will ride on top of the lube. As you time the engine the rocker will spread the lube out and the rocker/valve clearance will change on you.
Eyeballing the TDC mark: I find it much easier to line the pulley mark up with the mark on fan housing than the seam of the engine. I install the fan housing when timing my cams for this reason.
have fun!
Chris