Turning to Top Dead Center

[peteatgr]

I am preparing to install a new Pertronix Flame Thrower distributor and I want to make sure it's timed properly to TDC. I've never had to try to turn the engine before unless I had the radiator out and the fan removed making everything really easy and open to reach - simple to get a wrench on and turn away. I'd prefer not to have to take both both of those out again. Pardon my ignorance, but what's the easiest way/technique to turn the motor forward to TDC with everything installed? I've got the plugs out but just can't seem to get a good enough grip on anything. I've loosened the fan belt but am beginning to think maybe I should have it under tension and use it and rotating the water pump by hand to turn the block? I'm sure this gets done al the time, but I've never had to in 39 years..............or I can't remember back that far.

 

[Patrick67BJ8]

I am preparing to install a new Pertronix Flame Thrower distributor and I want to make sure it's timed properly to TDC. I've never had to try to turn the engine before unless I had the radiator out and the fan removed making everything really easy and open to reach - simple to get a wrench on and turn away. I'd prefer not to have to take both both of those out again. Pardon my ignorance, but what's the easiest way/technique to turn the motor forward to TDC with everything installed? I've got the plugs out but just can't seem to get a good enough grip on anything. I've loosened the fan belt but am beginning to think maybe I should have it under tension and use it and rotating the water pump by hand to turn the block? I'm sure this gets done al the time, but I've never had to in 39 years..............or I can't remember back that far.

With the spark plugs "out" and the car in "gear" (emergency brake "off"), push/pull the car and the engine will rotate.

 

[MikeAH100M]

I found that rocking the car by grabbing a tire was the easiest. To determine TDC, I used Norman Nock's suggestion of putting a wooden dowel in the spark plug hole #1. Move the car until the dowel is pushed out the farthest.

 

[steveg]

One of the posters described using a balloon to demonstrate TDC. I used this and found it to be accurate.

Perhaps he'll see this and post it again.

 

[richberman]

I did it using a compression tester with the Schraeder valve removed and replacing the compression gauge with a vacuum/pressure gauge. I purchased both on Amazon for around $20. I put one rear tire up on a jackstand, leaving the other tire on the ground, placed the car in 4th gear and removed all plugs to make it easier to turn. Was able to face the gauge the the right rear and see it as I move the tire until the gauge did not cause pressure or vacuum. Doubly confirmed by looking into the plug hole.

 

[steveg]

I did it using a compression tester with the Schraeder valve removed and replacing the compression gauge with a vacuum/pressure gauge. I purchased both on Amazon for around $20. I put on rear tire up on a jackstand, leaving the other tire on the ground, placed the car in 4th gear and removed all plugs to make it easier to turn. Was able to face the gauge the the right rear and see it as I move the tire until the gauge did not cause pressure or vacuum. Doubly confirmed by looking into the plug hole.

That's pretty cool!

 

[vette]

Put your fan belt back on snug. Remove spark plugs. from right side of car, put left hand on fan belt between generator and water pump pulley and press belt down to make tight. With right hand grab fan blade, ( MAKE SURE ALL POWER TO IGNITION IF OFF) pull or push fan blade to turn engine. To ensure TDC on the compression stroke vice 180* out, take distributor cap off, now turn engine till the pointer and the notch in pulley line up. When on TDC on the compression stroke the distributor rotor will point to approx 1 to 2 o'clock. If the rotor points in the opposite direction you are not on the compression stroke. Dave.

 

[peteatgr]

All good techniques and I've already made use of a couple. Thanks. I've got the engine positioned at TDC so that the notch on the fly wheel is directly opposite the pointer, but in that position the orientation of the distributor drive spindle appears to be 180 out of proper phase when I look at my distributor and the different size drive lobs cut in the face of the spindle itself. Is it possible that the fly wheel might have a "180 mark"? The notch appears professionally made.

I thought about removing and realigning the distributor drive spindle using the 5/16" fine thread bolt as a couple of manuals describe and the bolt threaded into the center of the spindle just fine. But I was still unable to remove the spindle. The spindle moves up and down a small fraction of an inch but feels like something is still holding/locking it in place. Anyone have any hints on techniques for removing the distributor spindle? Is there a set screw or something holding it? Or should I even be messing around with that?

 

[Keith_M]

You're on the exhaust stroke instead of the compression stroke. Turn the crank one full revolution and bring it back to TDC. That should bring the distributor to the correct place.

 

[peteatgr]

Got it Keith. Thank you.

 

[bob hughes]

As to the difficulty in removing the drive gear with a 5/16 BSF bolt, you would need to turn the gear as you pull it out - anti clockwise from memory, but it sounds like you would not need to do that now.

The best way to ensure that you are on the compression stroke TDC is to remove the valve cover and observe the rocker arms on the number one intake and exhaust - both valves should be closed.



Bob

 

[steveg]

As to the difficulty in removing the drive gear with a 5/16 BSF bolt, you would need to turn the gear as you pull it out - anti clockwise from memory, but it sounds like you would not need to do that now.

The best way to ensure that you are on the compression stroke TDC is to remove the valve cover and observe the rocker arms on the number one intake and exhaust - both valves should be closed.



Bob

In addition, the rockers for #1 cylinder will both be loose.