911 Camshaft Timing Help Needed Options

[Cfletch]

Hey there everyone, Newbie to Cam timing in general and working on putting the engine back together after repairing an oil leak from the Cam Thrust Plate o rings.

I am having what I hope is just a simple issue of misunderstanding on the timing of the cams and can use some help.

Engine is a 1974 2.7 CIS that retains the stock camshafts:
L:911.105.141.00 R:911.105.142.00

I currently am running into an issue where I am unable to get more adjustment out of my cam because I am hitting the piston with the valves when trying to rotate it in either direction.

Current process has been having the engine at Z1, having my distributor facing #1 cyl and having my piston at the top of the stroke confirmed by a whistle adaptor in the cylinder. Camshaft have the "911" at 12 o clock and the part number listed at 6 o clock. I have my #1 Intake Valve installed and set to correct valve clearance and have the timing chains tensioned by the stromksi tensioners. Pin is installed and nut is snugged up to the cam to get a reading for when rotating the engine. I have a drop gauge and z bar set up on the #1 intake valve and when rotating the engine over, the valve does not seem to lift at the correct position on the crank, and I am also not able to get the same lift I once had of 3745 Thousandths. I would like to rotate the cam at this point to get it adjusted slightly to get it to start raising at a better time relative to the crank, but when attempting to rotate it, I can feel interference with the valve and piston. I feel this going either clockwise or counterclockwise. I am stuck at this point and called it for the day and am looking for some help here.

Based on various videos and my 911 rebuild book from Wayne Dempsey. I seem to be doing everything correct, but just am not getting it to raise the correct amount and when trying to adjust the cam I run into clearance problems with the valve so I am clearly not in the right spot there. I am looking for any guidance here either in text format or possible a phone call tomorrow to walk through stuff. I have everything more or less set up ready to go and this is my last step before I am able to get it buttoned back up and reinstalled into the car.

One thing I had noticed is that we were getting relatively close to the expected measurement, but it was very far away from, Z1, probably about ~100 off from where it would be expected.

Today I had the help of Robert A, he drove up and we worked on repairing the leaky seals but had ran out of sunlight and time today. He left me his tools to hopefully wrap this job up and we were both stumped on this after a long day of work. Any help is most appreciated!

[rudedude]

I don’t know your cam stamping but the key slot should be facing up at z1

[Cfletch]

I don’t know your cam stamping but the key slot should be facing up at z1

Confirming the cam key slot is at 12 o clock

[rudedude]

Could you have switched sides? Left 1-3, has the further lobe separation

[rudedude]

Are you using z1 on the pulley or flywheel? The z1 mark on my 2.0 flywheel is some 40 degrees off z1 on the pulley

[Robarabian]

Not possible.

We only removed one cam at a time. We removed the 1,2,3 side first, removed the cam chain housings, changed the gaskets / seals, and re-installed that cam. Then we did the 4,5,6 side.

We thought we were being smart and measured the overlap prior to tearing into it, so we could replicate it. Now we cant for some reason. The overlap it had was slightly off from the book (Colin, you can speak to this) so we will approach it from the "book spec" versus what we measured with the stomski setup prior to removing it all.

Z1 on power stroke. Turn the crank and the overlap is not coming on til we are just about at TDC and the numbers rise After TDC. My experience has always been that the overlap happens prior to TDC.. hence the "overlap."


The keyways were facing up both sides when we index the cams. On his cams, the part number is on the bottom, "911" is on top and I think there is a small dot as well.

Could you have switched sides? Left 1-3, has the further lobe separation

[sixnotfour]

If #1 is at TDC and rotor pointing at firing #1..It should be on compression stroke intake valve closed ..
and # 4 will be at overlap..

[sixnotfour]

0.03745 ??? #1 at overlap Rotor pointing to #4 at z1

[sixnotfour]

Is .3745 total lift ? (IMG:style_emoticons/default/idea.gif) (IMG:style_emoticons/default/popcorn[1].gif)