[Formulas]

I use the brass threaded plugs, NO drilling drama

[rohrt]

Finally back at it. I got the cloyes 9 keyway TC set. Decided to start at 2 deg adv.

While struggling to get the cam gear on i knocked the woodruff key out of place. SOB! Turns out it was an ofset key! That would have been good to know befor i started.

So not wanting or needing to mess with that i ran to the hardware store. I got a 3/16 x 3/4 key. It was a 1/1000 wider the the one that cam out and not wanting to go in very easy. I used a flat file on it to trim it down ever so slightly and still had to use a few taps with a flat punch to put it in place.

I ran the numbers 3 times and im right at 107.5 to 108 for the target 109 ICL.

I looked at the @.50 int #. I was at 3 deg BTDC, cam card says 6.

I'm happy with it. Right where i wanted to be.

I also found using a dial indicator to find tdc is more accurate then a piston stop.

A tight new chain also makes it easier.

[wbnapier]

I have the same Stump Puller cam. Here is the cam card, and from my amateur reading, yes it is ground +5. The hand written numbers are from my degreeing.

[darbikrash]

Originally Posted by rohrt

I also found using a dial indicator to find tdc is more accurate then a piston stop.

I have not found this to be true. The dial indicator will give you a different number than the piston stop method, but it is not the correct number.

[AG]

I respectfully disagree with that statement.

[rohrt]

Originally Posted by darbikrash

I have not found this to be true. The dial indicator will give you a different number than the piston stop method, but it is not the correct number.

I used both a piston stop and the dial indicator. If you figure out TDC with the dial indicator just like the ILC by measuring @.50 on the up/down stroke it worked pretty well for me.

[darbikrash]

Often people use a dial indicator to directly measure the piston at its highest point, which is not a good method as at TDC there is a poor relationship to the crankshaft rotational position- which is what the real goal is.

If you are using the indicator on the piston as a reference before TDC (for example .50”) and then rotating the engine the opposite direction, also to the .50” reading, then deriving TDC by dividing the degree wheel stopping points by 2, then you are using the piston stop method, just with a dial indicator instead of a hard stop. I would expect this to be very close to the same number as it is the same method, which is to say deriving TDC and not directly measuring it.

There are still differences between the hard piston stop and the dial indicator even using this method. There are clearances in the rod journal/piston pin which are “washed out” by rotating against a hard stop, which are not accounted for, at least reliably, from a “zero force” contact of an indicator tip.

So if there were differences between the indicator and the hard stop I would still believe the hard stop over the indicator for this reason. Trying to directly measure TDC with the indicator at the top of stroke will give bad numbers, which is what I thought you were doing.

I think your method Is fine, and I would expect little difference between the stop and the indicator. What difference did you measure?

[lust4speed]

No one I know uses a dial indicator method you describe. If you get a wrong number using a dial indicator then you are simply using it incorrectly. All measurements with a dial indicator should be in the direction of engine rotation at .050" before and .050" after rotating in the same direction of travel. At no time do we worry about attempting to measure the piston at its highest point. The amount of dwell would make the task impossible. Same when degreeing the cam - it has to be done in the same direction. If you trust the dial indicator for the cam why in the world would you think it to be any less accurate finding TDC? If the crank travels in the same direction then clearances have been taken up and will not change.