The cam degree article in the October 07 issue is nice piece and will be very useful for many folks.  I would like to take a small issue with the way the author described the use of a piston stop to find TDC.  I've never seen anyone use the method demonstrated in the article with the piston stop.  As mentioned, a dial indicator is accurate but it's a bit hard to do easily unless you have a magneting deck bridge to free that extra hand.  A different piston stop method is easier and just as accurate.  The method I use just requires the stop be set well before TDC and you do a little math.  Math = ugh.

Home made piston stop - 3/4 angle iron and some bolts.


Attach the stop to the deck, then rotate the engine until the piston just touches the stop.  Read the degree wheel - 35 BTDC here.


Rotate in the opposite direction - read the wheel as ATDC, 35 degrees here.  


The mid point is TDC.  After you learn your stop, it gets easier.  Mine stops the piston at 35 degrees on a 351C, so I can get TDC located quick.  If the readings are off as they will be when first attaching the degree wheel, you just adjust the wheel to split the difference.  For example, if the wheel stops at 50 BTDC and 20 ATDC, you can add the two numbers (50 + 20 = 70) and divide by two - in this example you get 35.  Could be anything, it doesn't matter.  The number is just the spot where you split the difference between each side of the wheel. You don't move the crank, you just reset the wheel or pointer to 35 (this example, or whatever number) and you're set.  Rotate the engine back as a double check and you should get the same number on the other side of TDC.  

The article also left out another double check for the cam timing - lobe centerline.  This is pretty easy too and is as accurate or more so than the open/close at .050   The open and close and the centerline need to be checked to insure the cam is ground correctly.  It's also useful for putting the valve events where you want them.

In this engine, I want 107 on the intake and 109 on the exhaust.  Crane specs are 103 and 113 for +5 advance with 108 lobe separation.  I want only +1 advance, so that changes the required centerlines to 107/109.

Rotate the engine clockwise until the dial indicator shows "0" just before peak lift.  Read the degree wheel - 78 ATDC.


Keep going clockwise past peak lift until the dial indicator reads "0" again.  136 ATDC here  (on this wheel, you quick figure it as 180 - 44 = 136, got a headache yet?)


Add the readings - 78 + 136 = 214.  Divide by two, you get 107.  It's dead on where I need it.  The .050 readings were 13 BTDC and 46 ABDC, cam specs listed 12 BTDC and 46 ABDC.  

The exhaust worked the same way.  The readings were 147 BTDC and 71 BTDC:  147 + 71 = 218  218 / 2 = 109.  Spot on.

The dial indication cam follower is also home made and complicated - it's an old lifter with a 3" long  5/16" bolt JB Welded to the top.  


The suggestion to check more than one cylinder is a good one.  CNC machines are very accurate and the cam companies work hard to provide a good product.  But, we're all still human and things happen whether we like it or not.  

Some good tips there Falcon67! Thanks for the feedback and for sharing with our other forum users.

As you know, every engine builder does things their own way and some of them like taking the high road and some the low road.

We appreciate your willingness to jump in and offer your experience.

Mark