Timing mystery

K

keeeef

Member
Hi

I,ve been having timing issues for the past couple of months which is now so bad the car will only start and run for a few seconds. My 29 Sedan has a 12v FSI Electronic distributor so no points to worry about.I have fitted a new aluminium timing gear, set top dead centre then aligned the distributor to #1 plug, the car will start immediately but then splutter and die!
I then check the timing marks again and rotor arm is no longer pointing at #1 plug at tdc? I would say its moved a 1/4 of a turn, not the distributor beacause I have been locking it with the screw and marking the case.
What could be the cause?

Thanks
Keith
 
Keith - I would check to see if the distributor shaft can be rotated with the engine off, of course. Perhaps a pin or engagement wedge has sheared off the shaft.
 
Sounds like something might be wrong with the distributor drive shaft or drive gear. Why not pull off the distributor cap and turn the engine over with the starter. See if the rotor seems to turn okay. Your rotor isn't cracked is it? I'm sure others will have suggestions. Good luck.
 
Pulled the distributor, shaft and couplings look ok and rotor arm is good. If insert a screw driver in to the drive shaft slot I can turn it with only a slight resistance and no movement from the engine, ie timing mark dosesn't move. Is that right? What couples the end of the distributor shaft to the camshaft?
 

Attachments

  • timing 1.jpg
    timing 1.jpg
    66.9 KB · Views: 70
  • timing 2.jpg
    timing 2.jpg
    63.7 KB · Views: 72
The possibility exists for play in two separate places. The first is in the secondary shaft between the distributor and the distributor drive gear. The tang slots on the secondary shaft could be worn. The second place for gaining excessive play is wear in the distributor-oil pump drive gear to camshaft center gear. If excessive play is found in the distributor drive gear, an oversize gear is available.

Most Model A engines have some play in the distributor drive. This is the reason for always tightening the distributor cam screw while holding the cam in a clockwise direction eliminating all play. Thus, as the distributor rotates counterclockwise, the play is always forced out and not changing the original set point of timing.
 
When you say you can turn the drive shaft with only slight resistance do you mean that you can move it just a little (an eighth of an inch or so) or turn it all the way around? The latter is not right. That would suggest to me the possibility (assuming it's a two piece drive shaft) that the pin in the connecting collar has sheared off.
 
The teeth on the camshaft could also be worn out enough to cause the problem. Of course if the distributor shaft stops turning due to camshaft gear wear, then the oil pump stops too. I'd pull the side cover and remove the drive gear, then look down at the camshaft teeth. I've seen them worn thin, but not totally shot.
 
Thanks Bob, do they fail very often? Les Andrews manual mentions little ever goes wrong with the oil pump but can't think of anything else that would cause the timing to slip?
 
JBill, yes I can turn the gear at the very bottom of the distributor shaft quite easily all the way around not just an eigth or so!! So where is the 2 piece drive shaft, inside the valve cover?
 
If you take a look at some on-line vendor's distributor rebuild kit you'll see what the two piece shaft looks like, and the collar that keeps the upper and lower shafts aligned. I've had second thoughts about the pin in that collar shearing off. That wouldn't create the problem you're experiencing. It's more likely something like what Pilotdave or Tom are suggesting.
 
The lower piece should stick just above the head gasket and can be removed with a magnet, or long thin pliers, if it isn't rusted in place as sometimes happens.
 
It's only been a few hours since I went through the same thing (again). I used the Nurex timing tool to set the timing and it was waaay advanced. I have a scale on the front of the motor and a white mark on the pulley that line up at TDC. It was about 25 degrees out at an idle. This is not the first time I've had to fudge the timing with that distributor. The problem lies in the faulty trigger (the piece that the rotor button goes onto) in the distributor. FS had a batch of them about 3 years ago that were way off. When I spoke to them, they said that they had a fault in the software for the machine that makes them and each one was a little further off than the previous one till they were so bad that the car wouldn't run. I made mine run, and well too by setting the timing at whatever position it took to get the timing marks right at an idle. It is so far off, I had to solder a piece of brass shim onto the rotor button to allow for the advance.
Maybe you have one of those faulty triggers.
 
Hi Keith,

FWIW: From past experiences.

In not trying to sound critical ............. this is only one (1) of many Forum problems one sees on Model A Forums over the past 20+ years with "non-original" distributors and "non-original electrical set-ups where repair of same is unfamiliar to most Model A owners.

If a Model A owner is on a tour .......... away from home .......... with a group of old time Model A owners .............. with an installed "non-original" malfunctioning distributor ................ appears chances of not finding the problem and being expensively towed home is far greater than if you had the all too familiar "original" distributor.

In trying "not" to advise using a "non-original" distributor as a boat anchor ...... if one travels a few miles from home, it is never a bad idea to have a spare, functioning "original" distributor to install in one's stalling Model A ............. and continue to drive along with your wife and possibly a group .............. while one is fiercely scratching his head, and moaning and gnashing his teeth in trying to figure out how to repair one's "non-original" distributor.

Wives, girl friends, and family members sometimes loose faith quickly in Model A's after being stranded on the side of the road "once".

In the future, just hope this helps anybody to continue driving next time this happens with any type of "non-original" electrical Model A set up.
 
If you are setting the timing in matter what the play may be in the distributor drive shafts it shouldn't be moving if he cam is tight .
I'm bit a fan of aftermarket distributors so your in you own there .. But as Vince said ( forever 4) you may have an older poor repro pressed in distributor drive gear and shaft. They are prone to cause issues. The slop in the drive is accounted for in setting the distributor cam/timing . So it shouldn't be changing if the cam is tight. I would NEVER use an oversize distributor drive gear . Asking for trouble in that one . Pull the dist and valve cover and remove and check out . Quick service fix

Larry Shepard
 
This is the gear by itself. Like Vince said at one time they made them as
a separate shaft and gear---not good.

Bob
 

Attachments

  • A6551-8312-xl.jpg
    A6551-8312-xl.jpg
    42.2 KB · Views: 12
And this is where you will find that distributor/oil pump drive gear...it's right in the center, under the valve gallery cover. The spring holds it in...remove the spring and it ought to just lift out...
 

Attachments

  • 2015_0814modelajeep1541.jpg
    2015_0814modelajeep1541.jpg
    57.2 KB · Views: 62
Problem solved! Sure enough the gear on the end of the shaft is spinning freely. New one ordered so hopefully back on the road in a few days.

Thanks again for your invaluable help and advice.
 
You must log in or register to reply here.
Back
Top