Electrical: engine won't stay timed update

[T.J lavallee]

I had previously posted that my 60' 259 V8 Lark's engine would not stay timed. After driving the car at highway speeds (55 mph) for twenty miles the engine would retard from it's original 4 degree timing light setting. I received numerous good suggestions on what the cause might be from members on this post. After investigating all of them with the same results I pulled the distributor as was suggested to inspect for sheared pins. The pins were not sheared. There was no slop in the housing, the shaft turned smoothly, the cam had little wear and the weights and springs were fine along with the points. I ordered a new gasket and hold down. I posted that I would bring the distributor to a friend of mine who is a Certified Master Mechanic. He agreed with me that there was nothing wrong with the distributor and after telling him that the rotor responded almost immediately to small rotations of the crank either clockwise or counterclockwise we ruled out a worn timing gear. He then told me he had seen this before and suggested that the rubber in the harmonic balancer was worn at the holes that the pulley studs passed through and was slipping. I never thought of that! Has anyone out there ever had any experience with this happening? I looked through the S.I. catalog but couldn't find the two rubbers. I have searched their web site but I really don't know what they are listed as. Any information would be greatly appreciated. Thanks in advance.

[karterfred88]

If you had to move the distributor to get it to run correctly, I doubt the balancer is moving, since when you retimed it, you used the mark on it to reset the timing and it ran and started better, indicating it had actually changed. Did you physically mark the distributor base and index it to the top of the block with paint or a magic marker? Did it actually move after setting the timing and running it or not? If it didn't move and the timing changed and needed to be advanced again, something has to be slipping internally somewhere, the rotor is moving on the shaft or your distributor cap is moving independently of the distributor base. Is the tang on the distributor body engaging the cap so it can't move with the clips securely snapped in place, the flat in the rotor a tight fit to the shaft flat? Unless you have a R engine the balancer is very simple- a new one here-but I don't think it will solve your problem

http://www.parts123.com/parts123/yb.dll?parta~dyndetail~Z5Z5Z50001003a~Z5Z5Z5AAILG~P35.00~~~~S4LP17MZ4771175861350B~Z5Z5Z5~Z5Z5Z50001003a

[rkapteyn]

I think that if the rubber washers with the six nubs on it are shot
the indicator marks on the front pulley will move.

Replace these

[T.J lavallee]

This is a GM window style distributor so the cap has a square hole and a round hole to align the cap to the like distributor tanks and spring loaded clamps that are pushed down with a screw driver and rotated a quarter turn to engage the L shaped clamps to the distributor detents underneath the housing. The rotor is screwed down with two screws to secure it to the distributor. Maybe, somehow, the cap is moving but it seemed tight and secure when it was installed. I'll test the fit of the cap before I reinstall the distributor. Thank you for the suggestions.

[karterfred88]

This is a GM window style distributor so the cap has a square hole and a round hole to align the cap to the like distributor tanks and spring loaded clamps that are pushed down with a screw driver and rotated a quarter turn to engage the L shaped clamps to the distributor detents underneath the housing. The rotor is screwed down with two screws to secure it to the distributor. Maybe, somehow, the cap is moving but it seemed tight and secure when it was installed. I'll test the fit of the cap before I reinstall the distributor. Thank you for the suggestions.

I assumed it was a Prestolite, but same guide lines stand: if you always have to advance it there is little place for error if the housing remains stationary with respect to the block. A loose or moving damper will result in both a retard and advance reading, not consistently in on direction, unless the bolts are slotting the holes. The rubber doesn't bond the inner and outer ring like more modern cars and the R engines. See Bob's image in #3. Good luck!

[Dan Timberlake]

Even if the cap shifts a little it does not change the timing. The points opening controls that.

Like wise, as others said, if the damper does slip, the ignition timing remains the same. It is only when viewing with a timing light that the timing "looks" as if it is wrong.

The typical Studebaker damper with thru bolts nestled in rubber bushings can't slip very far, even if the rubber gets extremely pounded out.
And, again, even if it did, that would not change when the sparks plugs fire.

My money today is a witness mark on the distributor housing onto the engine will show motion.

[Charlie D]

Anthony,

I know you must have tried this but here goes. If I remember your original thread correctly, you like 4 degrees BTDC and it retards from there. My 259 runs its best at 9 degrees BTDC. Have you tried setting it at say 8 degrees BTDC and see if it will retard to the 4 degrees BTDC or if it retards all the way to TDC?

Charlie D.

[karterfred88]

I don't have a parts manual with the hold down clamp part numbers, but is it possible you have a hold down clamp for a Prestolite instead of a Delco? Don't know if there is any differences in the distributor body at the clamping ring area, but if there is, that may be the source of the distributor moving. Somebody could have switched distributors and not switched the hold down. Really reaching here-sorry!

[StudeRich]

Good guess, but Stude. V8 hold down clamps are all the same, like most all parts of the Engines.

[T.J lavallee]

Thank you all for your input. This sure is getting baffling but I will keep trying to get to the root of the car's problem...if it doesn't drive me to the looney bin first!

[bobgould]

damper cushion

I had previously posted that my 60' 259 V8 Lark's engine would not stay timed. After driving the car at highway speeds (55 mph) for twenty miles the engine would retard from it's original 4 degree timing light setting. I received numerous good suggestions on what the cause might be from members on this post. After investigating all of them with the same results I pulled the distributor as was suggested to inspect for sheared pins. The pins were not sheared. There was no slop in the housing, the shaft turned smoothly, the cam had little wear and the weights and springs were fine along with the points. I ordered a new gasket and hold down. I posted that I would bring the distributor to a friend of mine who is a Certified Master Mechanic. He agreed with me that there was nothing wrong with the distributor and after telling him that the rotor responded almost immediately to small rotations of the crank either clockwise or counterclockwise we ruled out a worn timing gear. He then told me he had seen this before and suggested that the rubber in the harmonic balancer was worn at the holes that the pulley studs passed through and was slipping. I never thought of that! Has anyone out there ever had any experience with this happening? I looked through the S.I. catalog but couldn't find the two rubbers. I have searched their web site but I really don't know what they are listed as. Any information would be greatly appreciated. Thanks in advance.

I had posted a reply earlier, had the same thing happen on my 259 engine, S/I part # 186703-4, easy to do pay attension to assembly has one staggered bolt hole. Hope this helps.

[JoeHall]

How bout the mechanical advance mechanism in the distributor. Is everything assembled and operating exactly as it is supposed to?

[T.J lavallee]

How bout the mechanical advance mechanism in the distributor. Is everything assembled and operating exactly as it is supposed to?

Yes it's been checked out carefully. Nothing wrong with the distributor but thanks anyway.

[57pack]

Purchased a set of harmonic balancer rubber bushings from SI for my 57 Packard this past winter.