Tricks to locate TDC

Slotblog

Slotblog

Senior Member
In trying to install my new Bert's rebuilt distributor, the timing pin TDC location isn't working very well for me.

Pulling the number one plug, I can of course see the piston and can get a gross location of TDC in that manner, but as most will know there is a small amount of piston movement over a fair number of crank degrees as the crank throw goes "over the top".

Sure, I can pull the head and use my dial indicator to nail TDC, but I'd like to avoid that (and I don't have another head gasket on hand).

Anyone have a good trick for TDC location if the timing pin routine doesn't work well?
 
Right, the easiest way is to pull the 4 plugs to make the engine easy to roll over, then put your finger on #1 hole to feel for compression. When the compression stoke is coming to an end you can push the timing pin in with your left hand while slowly pulling up on the crank with your right hand.

Once the pin falls into the dimple, then you could use white fingernail polish to make a mark on the pulley and timing cover that line up, so you can look at them the next time.
 
harleytoprock said:
Why is the timing pin not working for you? Does the pin drop in but you feel it is too sloppy to be acurate?
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I'm not feeling anything "drop in". It feels like the pin is going over a scratch or an imperfection in the gear.

Forgot about holding a thumb over the spark plug hole to determine the compression stroke. Thanks for that reminder.

I've tried using a mirror and a light but haven't been able to see the hole in the timing gear so far.

In all honesty, we were a little tight on time yesterday and had to stop to go eat some turkey, if you can believe that...

Part of the problem is that this car didn't come with a hand crank, so we're pushing the car in high gear to turn the motor over...
 
I use the mirror approach, I also ground the point on the pin a little more sharply so it finds the timing gear more easily. Works a treat now.
 
Sometimes that little dimple can be very hard to feel. Last summer at French Lick a vender was selling a pin that was cut a little sharper and had a groove cut in that lines up with the outer casting when it finds the dimple. I bought one just to keep in my tool bag. I was helping a friend time his car and so I tried it out. It really works and shows when you are in the right spot. I don't know who the vender is, but someone reading this may remember.
 
Bratton's sells an "Easy Timing Pin Key Ring" . Part #7891, on page 2 of 2014 parts catalog. $4.25.

It works well. Best to have 2 people, one to push car forward in third gear as the other feels for the dimple. But it can be done single handed also.
Smurph
 
If you have a helper, you can jack up one rear wheel and have the helper slowly turn the wheel with the transmission in gear to turn the engine over. It's less effort and struggling than pushing the car back and forth.

Now - to find TDC...

Install a pointer wire on a front timing cover bolt. Turn the engine over until the piston visually just stops rising on TDC of the compression stroke. Make a mark on the front pulley where the pointer wire is pointing. Now turn the engine over in the opposite direction until the piston stops rising on TDC on what would be the "back side" of the compression stroke. Make another mark on the pulley where the wire is pointing. If you measure the distance between the two marks and place a third mark halfway between, this third mark will be your true TDC. Hopefully I have described this clearly enough.
 
Excellent, Mr. Sutton!

I like this better than futzing with the pin and it should be more accurate as well.
 
The best and most accurate method is using ( and ford intended) the timing pin . If you have to you can sharpen the pin slightly on a grinder , but to be most accurate on the timing the dimple in the gear which is rounded will usually work with most stick timing pins . Some gears don't have a big of dimple than others. This is what I do and it works every time.
I have done hundreds .

Get the engine rotated so the number is pointing to the distributor hold down (9 o'clock as looking from the front). Using the crank I get both feet inside the bumper on use my right leg and knee pressing downward on the crank while reaching around to push the pin . You have good control this way ( at least for me) . As the engine begins to free up ( plugs in of course ) you know the pin is about to drop in. Use slight pressure with the knee on the crank till the pin drops in. You will feel it... You just have to feel it. You can rotate it as you have described rocking it back and forth but I would recommend getting a crank

It's really very easy. Don't forget to retard your spark, make sure you have proper retard and advance in the distributor housing window and set your points . I like .020 myself . Spec is .018-.022. Once gap is set with rotational slop accounted for the points should just start to open with the last very small bit of rotation on the cam (counterclockwise )

Piece if cake....
Larry Shepard
 
Slotblog said:
Excellent, Mr. Sutton!

I like this better than futzing with the pin and it should be more accurate as well.
Click to expand...

Honestly the are all sorts of methods folks try to come up with but honestly there is no method more accurate than ford intended way of the timing pin and setting the distributor properly. This is the simplest of all mechanical operations on the car. Nit quite sure why some folks Make it more difficult and inaccurate as they do. Not trying to ruffle feathers , but the timing pin works perfect if you know how to use it
Larry
 
forever4 said:
Or, you could just use the accurate and simple way Ford provided using the camshaft timing pin. geez.
Click to expand...

This is the type of attitude that makes me hesitant to post replies.

The original poster stated that he did not currently have a hand crank and was unable to get the timing pin to drop in. Not knowing why the pin won't drop, I provided a solution to him. This is a solution that carries over beyond the world of model A's and I have used it many times on stationary engines where the mag trip mark was absent or not visable. While I agree that it is easier to use a hand crank and the timing pin, if that method is not plausible, my suggestion will work with perfectly acceptable accuracy.

Best of luck to the original poster with whatever method he gets to work for him. I hope he gets his car back on the road and is able to enjoy it this weekend.
 
Finding top dead center is easy IF the dimple in the timing gear is deep enough. As others suggested try sharpening up the pin and see if it helps.
Here is yet another suggestion if that doesn't help.
With all the plugs removed put a finger over #1 spark plug hole to find the compression stroke.
Then put a piece of straight wire down the spark plug hole to rest on top of the piston. Continue turning over the engine until the wire stops rising.
Better than trying to look down the spark plug hole.
 
Turning engine over with out hand crank, you can use a socket 1 3/8
to turn it over easier. A 3/8 bolt with heat srink a round shank and grind
end down to a point might do it! Many ways to get the job done,some easy
some harder but getting it timed is what is needed IMO :-)
 
i think without the hand crank or the angled wrench that goes on the crank nut that pushing the car in 3rd it would be easy to go past the dimple...you can only feel the dimple for a microsecond as you turn the crank nut slowly....
 
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