Ignition: engine won't stay timmed UPDATE

[T.J lavallee]

I pulled my distributor on my 60' 259 Lark this morning. The securing pins were not sheared. I did, however, find that the end play at the gear hub and spacer was in excess of .065". The manual recommends no less than .035" to no more than .065". I believe this is not the cause of my problem. I also noticed that the oil shaft below the gear has play in it and wobbles a bit. I could find no reference to this shaft's tolerances in the manual. Does anyone know if this shaft should have some play and wobble a bit? Thanks in advance.

[JoeHall]

Quote: "No hesitation and plenty of throttle response for three or four 20 mile trips then it begins to start harder (it usually pops right off) and starts hesitating when accelerating after a slow turn. I get the car home and check the timing and it's moved to an advanced state."

The $64,000 question: What is an, "advanced state"? I interpreted timing was advancing permanently. For that to happen, something must be slipping. If not the pin, the distributor housing itself, must be slipping. The excess .018" end play may cause flutter, but no permanent movement in either direction.

Further, a few degrees' flutter would not make it hard to restart. If only shut down 15-30 minutes, you may be dealing with heat soak, which has nothing to do with spark.

Still further, spark would have nothing to do with, hesitation "after a slow turn."

[T.J lavallee]

The timing in question is retarding not advancing, hence the hesitation and harder starting. If I readjust the timing to where it should be it starts right up no matter how "hot" the engine is. Since as you indicate it must be the distributor slipping I'm going to replace the hold down clamp after adding a spacer which you indicate would not alter the timing. Maybe the clamp is fatigued and not doing it's job. Thanks. I'm really at a loss for any other explanations.

[karterfred88]

Well I guess it "could" happen if the clamp wasn't clamping tightly, it would be unusual. Did you check that you had a gasket under the distributor where it goes into the block? It really doesn't take much pressure (or shouldn't) to hold the distributor in position, one finger pressure at 5000 RPM should do it. Wipe the housing base clean and top of block in some easily viewed area, use a magic marker to put a line across the housing onto the block top, after you set the timing and lock it down. Then you'll know for sure if the housing is rotating or not. If it does move, I'd be looking at shaft bearings or bushings seizing up inside the housing, causing so much drag that the clamp can't hold it from moving. Good luck, hope it's just the clamp not getting tight enough.

[52-fan]

Regarding your question about the shaft to the oil pump "wobbling". The V-8 distributors I have removed all have some movement. I guess this is to allow for slight misalignment.

[T.J lavallee]

Thank you all for your input. The shaft spins feely and there is no slop in the housing. The weights are moving freely and the return springs appear to have plenty of return strength. There is virtually no wear on the cam lobes and the contact breakers are in good condition. The vacuum advance plate operates smoothly with vacuum applied and returns quickly to it's position when vacuum is released. I'm taking the distributor down to a very qualified and trusted Master Mechanic to see if I've over looked something in the unit. Maybe he'll see something that's obvious to him that a shade tree mechanic like me has overlooked.