Cam degree dilemma

[subcom]

I'm putting together a 5.9 Magnum, stock bottom end, rebuilt.
I sent the factory roller hyd cam off for a regrind and I am now validating the specs with the degree wheel and dial indicator. I'm using the intake center line method outlined in one of the Mopar small block books and referenced else where online. Heads are OFF the engine.

I'm afraid the cam was not ground to the specs on the cam card and I need some input from you gurus before I call up the cam shop and make myself sound like an idiot.

I'm locating TDC with the dial indicator on top of the #1 piston and I feel pretty comfortable I'm nailing it on the bulls eye. I triple check everything. The spec indicates a 108 center line on the intake, 116 on the exhaust. I'm finding center line by measuring with the roller lifter in place, dial indicator on the biggest/flatest surface I can find on the lifter and bringing it up to 0.050 before it hits max lift, recording the number on the degree wheel, then going 0.050 after max lift, recording the number, add the two numbers then divide by two. The interesting part is when measuring the intake center line I'm getting a consistent 116. So I measure the exhaust lobe center line. Guess what? 108. The numbers are inverted. And yes I know intake is the second lifter from the front of the engine on the #1 cylinder...unless I'm doing all of this work in a parallel and backwards universe.

So I went on to #3 cylinder and repeat the exercise. Same results, center line numbers are backwards. Lobe lift is correct at .332 on the 4 lobes I've measured so that part lines up with whats on the cam card.

Is there any other variable in my setup that could be producing these numbers? I'm using a new Coyes double chain, lining it up dot-to-dot but it does support +/- 4 degrees in either direction. I removed and reinstalled the timing chain set thinking maybe I was off a tooth in one direction or the other but I'm getting the same results. I've double and triple checked TDC. Could it just be that the cam grinder punched there number's in wrong when they were setting up the machine to grind this thing? Thanks for any input folks.

 

[67Dart273]

You are forgetting a huge point --- and that is the whole POINT of degreeing a cam is so that you can CORRECT an incorrect timing issue, or if you are using the cam "for a different purpose" IE want to move the torque band up or down, you can "put the cam where you think it will do the most good."

There could be several variables here-------

the cam could be ground a tad off

the cam drive could be a tad off

the crank key could be a smidgeon off

the block line bore could be somewhat shifted

ALL these factors and probably more (RE: Murphy's Law) could possibly add up in the one direction you don't "wish."

That's why we have cam drives which you can change, offset bushings, keys, etc

TDC:

You say you think you did this correctly, just HOW did you do it? Describe?

So far as the cam being "right or wrong" if you have the cam card, IE timing events, you can plot them, and if the ICL is off a little you can add the difference while plotting them

 

[subcom]

Thanks for the response.
TDC- dial indicator mounted over center of piston. Rotate piston up till .100 before TDC, note degree mark. Continue rotating over the top till .100 after TDC, note degree wheel. Add, divide by two, adjust the pointer accordingly. Also, less scientific , but I bolted on the timing chain cover and put on the balancer and my TDC lined up with the cover. Thanks!

 

[crackedback]

How did you find TDC?

Best way is to set indicator at zero at top of bore and wind going UP both directions .050 short of your observed .000 reading. Note where pointer is and your true TDC is right in the middle.

 

[subcom]

Thanks crackedback.
I've done it the way I described above and your way as well. I'm pretty sure I have TDC identified.