Vintage Mustang Forums banner

1 - 13 of 13 Posts

·
Registered
Joined
·
405 Posts
Discussion Starter #1
In looking for the TDC marks, there don't appear to be any anymore. What do you do in a case like this?
 

·
Premium Member
1967 Mustang coupe
Joined
·
182 Posts
When i tested mine to see if it was accurate I:
- pulled all he plugs to make the roation easy by hand
- then plugged the piston 1 with my thumb as I rotated the crank
- Puff out on the compression stroke blows ur finger out (a towel or kleenex works fine too)
- stick a screwdriver in the plug hole and watch it go up until you can see the piston top
- stop and pull out screwdriver before end of travel (mine got pinched, so i learned this lesson)
- and watch piston (shine light down plug hole) until hits tdc (stops moving)
- Mark on pulley at TDC mark
 

·
Registered
Joined
·
1,146 Posts
I get very accurate TDC by putting a plastic straw down the #1 hole and going R then L back and forth with the crankshaft. Look at the position of the distributor rotor to be sure you are on the power stroke.
 

·
Registered
Joined
·
6,057 Posts
When i tested mine to see if it was accurate I:
- pulled all he plugs to make the roation easy by hand
- then plugged the piston 1 with my thumb as I rotated the crank
- Puff out on the compression stroke blows ur finger out (a towel or kleenex works fine too)
- stick a screwdriver in the plug hole and watch it go up until you can see the piston top
- stop and pull out screwdriver before end of travel (mine got pinched, so i learned this lesson)
- and watch piston (shine light down plug hole) until hits tdc (stops moving)
- Mark on pulley at TDC mark
While this is sometimes a "close enough" measurement, due to piston dwell it's not an accurate method of finding TDC.
 

·
Registered
Joined
·
36,471 Posts
When in doubt, go to the horse's mouth. Remove the balancer center bolt. The keyway slot is always perfectly centered on the top at TDC.
 
  • Like
Reactions: WestSD

·
Registered
Joined
·
4,896 Posts
When in doubt, go to the horse's mouth. Remove the balancer center bolt. The keyway slot is always perfectly centered on the top at TDC.
...but make sure it's on the compression stroke (rotor pointing #1) so that you are not 180 out. ;)

Granted, one can mark the balancer whether at true TDC or 180 out. :thumbsup:
 

·
Registered
Joined
·
263 Posts
Procedure for finding and marking TDC:
(0) Disconnect battery (don't want an accidental engine start)
(1) Remove piston #1 spark plug
(2) On piston1 make sure you're on the compression stroke by placing a finger in the spark plug hole to feel for outward pressure (you can also use a vac/pressure gauge with scharder valve removed on spark plug #1 hole to do the same thing).
(3) Put a piston stop into spark plug #1 hole.
(4) Rotate crank by hand clockwise until stop and mark temporarily on balancer
(5) Rotate crank by hand counterclockwise until stop and mark position temporarily on balancer
(6) Using a tape measure, mark halfway point between the markings above (#4 and #5) permanently on balancer as TDC
(7) Remove piston stop before trying to start car ;-)

Note: This method handles the "dwell" issue in finding TDC
 

·
Registered
Joined
·
47 Posts
Procedure for finding and marking TDC:
(0) Disconnect battery (don't want an accidental engine start)
(1) Remove piston #1 spark plug
(2) On piston1 make sure you're on the compression stroke by placing a finger in the spark plug hole to feel for outward pressure (you can also use a vac/pressure gauge with scharder valve removed on spark plug #1 hole to do the same thing).
(3) Put a piston stop into spark plug #1 hole.
(4) Rotate crank by hand clockwise until stop and mark temporarily on balancer
(5) Rotate crank by hand counterclockwise until stop and mark position temporarily on balancer
(6) Using a tape measure, mark halfway point between the markings above (#4 and #5) permanently on balancer as TDC
(7) Remove piston stop before trying to start car ;-)

Note: This method handles the "dwell" issue in finding TDC

Have you tried lightly sanding the outside of the balancer? I did that on mine (400 grit I think) and found the marks without too much issue. Then I did the above to check if they were accurate (they were). At that point I simply took a little black paint on a toothpick and re-painted the marks. Really, really easy to see now.
 

·
Registered
Joined
·
2,179 Posts
I've found that putting an object in #1 cylinder and just eyeballing can be accurate. I've successfully done it on cars with variable cam timing and several sensors that must be in sync. Never a problem.
 

·
Premium Member
Joined
·
13,170 Posts
Using an adjustable piston stop (Kelly_H posted a thread about making one from an anti-fouler) rotate the crank left and right until the piston hits the stop and mark the balancer. Then back off on the adjuster, rotate the crank and watch the 2 marks move closer to each other. Continue backing off the adjuster until the 2 marks are within 1/4" of each other. Then split the difference.
 

·
Registered
Joined
·
4,348 Posts
Why are you looking for TDC?

If its to index a cam, then the method P-51 described is acceptable. If its to remove and replace the dizzy, then being off a few degrees is ok.

If its a Ford balancer, then it has marks on it. They are probably hiding under a several coats of paint. Mine were.

I stick a cotton ball in the #1 plug hole. It shoots out on the compression stroke and leaves me both hands to rotate the engine over.
 

·
Registered
Joined
·
37,647 Posts
If you're too cheap to spring for a piston stop, grab an old spark plug and knock the guts out of the center. You can then tap the hole for a bolt.
 
1 - 13 of 13 Posts
Top