cam timing problem
 

doing a top end rebuild on a 1978 911 targa 3.0. trying to get the cam timing set, found some good info here to get me going in the right direction, got the left cam set to the spec for the cams, need more info on exactly how to set up the right cam, I'm running into interference when rotating the crank. I'm definitely missing something on the setup procedure. how should the rt cam be indexed when crank is at tdc #4?

Can you describe or post a video of the "interference"?

Did you insure the cam sprocket/s are in the proper depth position/s?

Cam timing procedure.........
 

Andy,

How did you set or orient the two cams at the start of the procedure? Did you set the valve clearance for both #1 & #4 cylinders @ 0.10 mm? If you did the cam timing for #1 correctly, there should be no interference when you move to cylinder #4. The initial setting of both cams should have the dot/930/woodruff on top. How many times did you make adjustment before you obtained the desired cam timing?

How many times did you measure the left cam timing? Multiple times? Are you aware that the ignition rotor should be pointing to cylinder #1 at start and end at #4?

The right cam timing is checked @TDC/Z1 same as the left cam but the rotor is pointing to #4 instead of #1. Repeat several times. Adjust cam sprocket accordingly to get the desired cam timing. Keep us posted.

Tony

You need to pin both cams to start. Both cams have to be fixed to start the settings and there is 2full revolutions to the complete settings.
Bruce

The cams are indexed the same on both sides. Match the angle of the left cam on the right cam and you will be close. I.E. Both dots up or down.

it seems that the valves are hitting the piston, checked the part numbers on the cams and according to the part numbers ive got the left and rt cams in the correct sides. ive tried the procedure numerous times and it will not make a complete revolution after the left cam is set. both cams are pinned with the 930/dot at #1 cyl tdc, dist pointing at #1. thanks for your help and input,Andy

Can you post a pic of your set up?

Then you need to start over because you're wrong at some poinT
Reference the crank. The pulley pin is at 9 o'clock, you can see it with the bolt out. Now back it up to 8 oclock.
Pull the pins on the cam gear, then the chain wheels. You want to see the key way on each cam up,
If it's not up, use 17 mm open wrench on the flats and turn the cams until the key way is up on each side.
Put cam gears back, tensioner so installed.
Turn the crank to 9 o'clock for pin locator on the pulley.
Pin both your cams. The left side rockersshould be both loose, the right side rocker intake moving the valve down. and the exhaust rocker loose
Dial gauge the left side and pin the number you want on one rotation. Once you're happy with the number match it on the other side with one rotation
Don't believe your distributor until you have cams timed then correct the distributor.
Bruce

going to video the procedure tomorrow. i'll remove sprockets and pulley to make sure all is lined up correct tonite

OP, welcome aboard!

WOW! I found the problem, after removing tensioners, sprockets and starting over as flat6pac suggested the problem has shown itself to me. the master link clip on the left chain must have been causing the problem. when I was putting the left cam sprocket back in I noticed the clip laying at the bottom of the housing. put it back on, assembled the rt side and tensioned the chains. now spins over with no interference and was able to set cam timing and recheck settings. thankfully it didn't fall off in the crank case.

That's odd, are you sure it will stay in place now??

Remember the clip is directional----------