The Ford Barn - Piston Stop

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Piston Stop - Timing

I want to verify the ignition timing on my 272, beginning with the #1 piston at the top of the compression stroke. I've read the term "Piston Stop" so what is the best way to confirm once I pull the spark plug? You guys use a cable tie? Car is manual shift, so I can push/pull in 3rd. to move the crank as needed. TY!

Re: Piston Stop - Timing

Checking to see if piston # 1 TDC matches the pulley timing marks can be easily done with the distributor in place.
With all the spark plugs out and the right side valve cover off I used a remote start switch, then a socket wrench on the crank pulley to rotate the engine until cyl # 1 intake valve opened & then closed.
With a finger in the cyl 1 spark plug hole I carefully continued turning the crank pulley (clockwise) with the socket wrench until I could feel the top of the piston coming up the last bit and stop moving, at TDC, which should line up with the timing pointer at the crank pulley.
The rotor will also be lined up with plug wire # 1 on the distributor cap.

Fyi, if there is a gasket of any kind between the distributor housing and block, remove it. It can ruin expensive parts. https://www.ctci.org/distributor-installation/

Depending on which style of crank pulley is on the engine, IF the weight ring has timing marks on it, the ring can easily slip out of position when the rubber layer fails.
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Re: Piston Stop - Timing

Quote:

A more accurate way to locate (TDC) is by using a piston stop tool. Screw the tool into the #1 spark plug hole by hand; and then slowly rotate the crankshaft by hand until the piston come up against the stop.

Mark your balancer with a marker, and then slowly rotate the crankshaft by hand in the opposite direction; until you come up against the stop again.

Mark your balancer again. Measure the distance between the two marks and divide by two. As a result, This is your (TDC).

SOURCE - https://dannysengineportal.com/top-d...of-its-stroke/

Read the entire article. Anything you do not understand, ask.

That is all there is to it finding TDC. The engine has to be turned by hand. Disconnect the NEG BAT TERM to prevent an accident.

Re: Piston Stop - Timing

OK...now I understand the meaning and use of Piston Stop - TY!

Re: Piston Stop - Timing

Quote:

Originally Posted by Anteek29 (Post 2022265)

OK...now I understand the meaning and use of Piston Stop - TY!

Maybe it's just me, yes a piston stop will work, I'm just not a fan of putting immovable metal objects into the spark plug holes.

Re: Piston Stop - Timing

Quote:

Originally Posted by dmsfrr (Post 2022317)

Maybe it's just me, yes a piston stop will work, I'm just not a fan of putting immovable metal objects into the spark plug holes.

There is no other quick way of determining TDC (non-HP engine). Only need to go further if the cam timing has been modified (using degree wheel). Of course you would need to ascertain timing set integrity before performing procedure.

ADDENDUM - (Fr. For More Info)

Quote:

What Is Chain Stretch?

The name ‘chain stretch’ is actually fairly misleading. Contrary to popular belief, the chain isn’t stretching at all. “The real name is chain elongation,” says Zerger, “It occurs when the chain articulates as it goes around the sprocket and pin wears on the bushing to the point that the length of the pitch elongates.”

SOURCE - https://www.ibtinc.com/how-to-measure-chain-stretch/