CAM timing - Sanity Check

[jjrowe]

I searched and found some had a similar issue but I never saw a resolution.

I am timing the cam on my 1976 911s. I am using modified "SC" cams by camgrinder that should be timed at between 1.4-1.7mm. I set the crank to TDC, set the cam with dot up (and verified that woodruff key is also up). I than adjust intake valve #1. Here is where I run into a question. I have no movement on my dial indicator until AFTER I turn the crank 360.

I have to turn the crank another 20 degrees to move 1.4mm. I set the timing by turning the crank 360 from TDC, stopping, and then moving the cam counterclockwise until I have movement of around 1.55mm. This seemed to work well.

Is it reasonable that I got no movement after 360 degrees from TDC? Wayne's rebuild book indicates that I should see the movement before 360.

Thanks,
Jesse

[lucittm]

Jesse,
I went through this also. Not only do you have to be at TDC, but you have to be on the firing cycle of cylinder #1. You can do this by verifying that once you are at TDC, you can also see the distributor fotor is pointing at the #1 plug wire. So you may have to go around twice to get to "firing" at TDC on #1 cylinder, then ensure you have the cam dots up.

1.55mm is good at TDC.

Mark

[jjrowe]

I am on TDC for cylinder 1. I have lined up the distributor with a mark that was already set. I am just wondering if it is reasonable that my cams are retarded enough that #1 intake doesn't get any lift until beyond TDC for #4. In the rebuild book it states that the lift should happen just before I get to TDC #4 (or 360 from TDC #1)

Jesse

[jjrowe]

Alright, I think I talked myself through this. Whether I have to move the cam backwards or the crank forward to get the measurement, it doesn't matter. This is only a function of which side my initial setting was off. The only thing that matters is that after I set the cam timing the intake valve on #1 should have opened 1.4-1.7mm when the crank is at TDC for cylinder #4.

Jesse

[Bobboloo]

Originally Posted by jjrowe

Alright, I think I talked myself through this. Whether I have to move the cam backwards or the crank forward to get the measurement, it doesn't matter. This is only a function of which side my initial setting was off. The only thing that matters is that after I set the cam timing the intake valve on #1 should have opened 1.4-1.7mm when the crank is at TDC for cylinder #4.

Jesse

Correct. You have answered your own question.