Timing puzzle

[daveymc29]

Like the guy said when his horse died, "never did that before." Well I put a timing mark on my pulley to aid in refinding top dead center for timing It also shows me approximately how much advance I have timed into the system. I drove today and on fair incline the car began to spew a tad of water. I checked the advance and moved the lever a bit toward retard and by then there was a cup ot so of water out on the hood and windscreen. When I got home I hooked up my timing light to see where thing lie before I start ripping things apart. I started the machine in full retard on the lever and notice the mark I put on the pulley is about 5 degrees before TDC. Great, but while watching it it moves to TDC to maybe 7 degrees BTDC, and back and forth a bit. Now I ask what would cause that? I drove the car to the NCRG meet a few days back and had response to the advance and no overheating though a couple of spots were pretty close to as warm as today.
I don't want to jump in with the screw driver and wrenches with no clue why the mark I made wouldn't remain steady. I also don't find much if any difference between no advance and about half advanced. All the way advanced the engine begins to stumble some at idle, but while driving didn't seem to be affected so much at full advance. (I have been running about half advanced most of the time and maybe 3/4 when going 55 mph or more with O/D. 6V neg grd., mid 50's points on nurex plate with the condernser on top of the modern plate. Puzzled?

[emf]

Is the point gap changing while it's running. Are the points locked down tight?


Frank

[daveymc29]

Will check tomorrow. Garage is too hot today to be a pleasant place to work. Besides tomorrow I may have more items to check before I get to pulling stuff apart.
Thanks for the quick response, probably the fault also. I'll let you know.

[Y-Blockhead]

How much 'play' do you have in your distributor shaft?

[1931 flamingo]

While running, if any play was taken out when the cam was set there is NO play. JMO
Paul in CT

[Y-Blockhead]

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Originally Posted by 1931 flamingo

While running, if any play was taken out when the cam was set there is NO play. JMO
Paul in CT

I meant sideways play, as in if he had lose bushings, not rotational. Every time the shaft moves away from centerline the point gap would change. Every time the point gap changes, the timing changes.

[daveymc29]

Things have cooled a bit and I had a nap so I'll look into it now and let you know what I find, without burning my tender fingers.

[Jacksonlll]

Check head torque,just to make sure.

[daveymc29]

Didn't re-torque the head but did remove distributor, set points to .020 and plugs to .035, retimed to about top dead center and it runs fine. Starts right up and idles smooth slowly and at a fast idle. All the while that little devil of a timing mark is jumping around from about TDC to maybe 10 degrees BTDC, though now I can really tell when it is fully retarded and when it is midway on the hand lever, even all the way advanced it seems to run fine but the timing mark according to my timing light is changing position, which of course the mark isn't changing but every several revs the #1 plug is firing at a different location. Going to try a different distributor tomorrow unless something more important comes up. (We have a daughter in a fight with pancreatic cancer so a lot of my life changes depending on how she feels at the moment. 6-17 UCSF is going in after the little devil and perhaps things will settle down a bit then. Sorry to have thrown that in but any prayers will be appreciated.)

Might also mention a nice service for Alex Jenke this afternoon. Many in attendance from all over. Good to see us supporting our own.

[TerryH]

So sorry to hear about your daughter......kind of puts Model A issues in perspective for sure. We will pray for her, and good luck with your timing.....

[aermotor]

Also praying for your daughter. I haven't seen any "official" timing procedure with a light so I would suspect that procedure. With uninsulated spark plug wire there is no telling where the spark is coming from. Toss it and forget it.

John

[Bob from Northport]

Using a crank handle or a socket on the crank nut/bolt, see if you can move with crank slightly back and forth slightly and watch distributor rotor movement. The timing gear may be worn-probably the problem

[Benson]

Posted to wrong thread looks like.

[frank55a]

I have found that very few distributor bodies fit tight on the distributor. This can cause some movement when the engine is running. I run some thin tape around the inside of the body where it sets on the distributor and trim it so it can not be seen. This will take the movement out of the body. Also check the gap from the rotor to the 4 points inside the body, I would have to check but I believe this should be 0.025, but it should be consistent and the points should be clean.

[BILL WILLIAMSON]

"maybe" the crank gear keyway is worn & shifting around???
Bill Jumpy

[nick c]

In front of the cam shaft there is a part called a spring and plunger that holds the cam shaft from moving forward, they get stuck in the compressed position and the cam moves in and out changing the timing.
carry on nick c

[daveymc29]

So Nick, how is the best way to check that? Seems my engine rebuilder put a screw and nut to lock it in the center of the bump ahead of the spring. I haven't messed with that. I would assume that it could be adjusted to put more pressure on the spring and plunger. I drove a bit this morning and all functions well. Starts immediately and warmed right up.
Ran smooth.

[Wick]

Throw away the timing light! Do a compression test,looking for a leaking head gasket. Flush the cooling system. Do a plug reading. Model A's are very forgiving on a few degrees off on the timing.
Wick

[rocket1]

Many rotors available today do not fit tightly on the distributor cam,I have found that repro's from years ago are made with better tolerances,which amount to a light press fit.

[nick c]

Dave, the engine builder replaced the spring and plunger with 3/4" fine all thread rod and a lock nut on the outside of timing cover, as I did on mine, most likely it will never need to be adjusted, I screwed the rod in till it contacts the cam then back off 1/16 of a turn, that would be about .004 on 3/4 x 16 threaded rod.
carry on