180° marks on crank pulley

[alexiskai]

Hi folks,

I am setting up the Nu-Rex precision timing kit for timing use, and the instructions state that you can check additional parameters on the engine if you make two dots on the pulley – a white one at TDC and another of a contrasting color at 180° opposite to TDC. My question is, does anyone have a convenient trick to precisely locate this opposing point on the pulley, assuming the car is fully assembled?

Right now my thought is to rig up a string or something to help me measure 90° rotation on the distributor cam screw, which has a handy straight line across the top. I also thought about trying to measure 180° from the front of the radiator as I turn the crank, but I don't see how I could get good precision. Anyway, I thought somebody might have come up with an easier way.

[johnneilson]

probably the easiest is a flexible tape around the circumference of the pulley.

J

[alexiskai]

I'm not quite following. Like, figure out the circumference of the pulley, divide by 2, cut a tape that long, and wrap around the pulley?

[GPierce]

Wrap the tape around the complete circumference and cut it so the ends butt together. Fold the tape end to end and cut it at half way fold. Lay it back on the pulley with one end at TDC. The other end will be the 180 degree point.

[jayvee34]

Originally Posted by GPierce

Wrap the tape around the complete circumference and cut it so the ends butt together. Fold the tape end to end and cut it at half way fold. Lay it back on the pulley with one end at TDC. The other end will be the 180 degree point.

I would first put a pointer @ TDC for a starting point if you have not already done so.

[jayvee34]

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Originally Posted by alexiskai

Hi folks,

I am setting up the Nu-Rex precision timing kit for timing use, and the instructions state that you can check additional parameters on the engine if you make two dots on the pulley – a white one at TDC and another of a contrasting color at 180° opposite to TDC. My question is, does anyone have a convenient trick to precisely locate this opposing point on the pulley, assuming the car is fully assembled.

I have this system on my car and it works perfect. no more guessing about
if I have my spark advanced not enough or too much.
I hope you enjoy it as I do mine.

[Y-Blockhead]

How about setting your timing at 0° #1 cylinder, mark the pulley adjacent to your pointer , then turn the crank clockwise until it fires at #2 and mark the pulley again adjacent to your pointer. A plug fires every 180°. 1-2-4-3.

[alexiskai]

Originally Posted by jayvee34

I have this system on my car and it works perfect. no more guessing about if I have my spark advanced not enough or too much.
I hope you enjoy it as I do mine.

My plan is to use it to fine-tune the Nu-Rex Automatic Timing system so it doesn't over-advance the spark for my HC head. I'm also going to take advantage of the opportunity to verify the rpm curve for the auto advance. We all refer to the curve published at fordgarage.com, but that was done on a test machine, not in an actual car. I'd like to see whether I can replicate that curve in the real world. I have a Bosch timing light that includes a tachometer, so I should be able to reproduce the data points.

I realize that you can't adjust the Nu-Rex advance the way you can adjust an FSI unit, but I will be able to determine where to place the spark advance lever so that it retards the overall curve by the right amount under load.

[alexiskai]

Originally Posted by Y-Blockhead

How about setting your timing at 0° #1 cylinder, mark the pulley, then turn the crank clockwise until it fires at #2 and mark the pulley again. A plug fires every 180°. 1-2-4-3.

Hmm, not firing the plugs per se, perhaps, but I could connect a test light that would go off when the points open as the cam rotates. That might be less of a pain than dealing with tape.

[jayvee34]

Originally Posted by alexiskai

My plan is to use it to fine-tune the Nu-Rex Automatic Timing system so it doesn't over-advance the spark for my HC head. I'm also going to take advantage of the opportunity to verify the rpm curve for the auto advance. We all refer to the curve published at fordgarage.com, but that was done on a test machine, not in an actual car. I'd like to see whether I can replicate that curve in the real world. I have a Bosch timing light that includes a tachometer, so I should be able to reproduce the data points.

I realize that you can't adjust the Nu-Rex advance the way you can adjust an FSI unit, but I will be able to determine where to place the spark advance lever so that it retards the overall curve by the right amount under load.

I'm running a HC head also, without looking it up, the The Nu Rex system starts at 0 degree's TDC and advances a max of 30 degrees. I installed mine
as per instructions and as said before, works perfect. Although here in Fla.,
I am not climbing any hills. Sounds like you do have it figured out.
Best Wishes.

[alexiskai]

Originally Posted by jayvee34

I'm running a HC head also, without looking it up, the The Nu Rex system starts at 0 degree's TDC and advances a max of 30 degrees.

That's roughly correct, 29°+/-. I have the Winfield 7:1 head, which has a reputation for knocking under load if the advance is too high (though no one is sure exactly how high). I figure it'll all be guessing in the dark if I don't at least have accurate advance measurements.

[Y-Blockhead]

Originally Posted by alexiskai

Hmm, not firing the plugs per se, perhaps, but I could connect a test light that would go off when the points open as the cam rotates. That might be less of a pain than dealing with tape.

I didn't mean it figuratively that a plug was firing...

[PotvinV8]

Knock the ceramic end off an old spark plug and drill/tap the middle to accept a bolt. Insert bolt into spark plug and install plug in head. Rotate engine until piston contacts the new piston stop, mark the pulley, then do the same in the opposite direction. Measure the difference and divide by two, there's your TDC. You can do the same to find 180-degrees out, or just install a timing tape and pointer as some have mentioned once you've determined TDC.

[redmodelt]

After you find your first point, make a degree wheel with notches 180 degrees apart, the diameter of your pulley. Lay it on the pulley and make your second mark. No fumbling with flexible tapes.

[Y-Blockhead]

Originally Posted by PotvinV8

Knock the ceramic end off an old spark plug and drill/tap the middle to accept a bolt. Insert bolt into spark plug and install plug in head. Rotate engine until piston contacts the new piston stop, mark the pulley, then do the same in the opposite direction. Measure the difference and divide by two, there's your TDC. You can do the same to find 180-degrees out, or just install a timing tape and pointer as some have mentioned once you've determined TDC.

Only problem with this is the spark plug is not directly over the piston in a Model A. Spark plug is located over the valves.