Timing changes when I tight distributor

[70Bronco]

Has anybody experienced a situation in which the timing changes when you tighten the distributor? I've never had that happen before. Get the timing set, tighten the distributor down, and it advances 20* at idle.

 

[toolmanmike]

Does it advance to 20° or does it advance 20° from where you had it set?

 

[Cranky]

There were times when I saw a change of a couple of degrees but not that many! Did you have the distributor out of the engine? If so, make sure the base is clean. Many moons ago I had one out and when reinstalling it, somehow a wire got in the way and that made the timing move a bit but it still wouldn't hurt to make sure the base is clean anyways. If you pull it, also inspect the housing for cracks....

 

[70Bronco]

Set it at 12* & when tightening the hold down, the timing moves to 30* and then stays there at idle.

 

[PP1RT]

How sloppy is the shaft?bushings?drive?

 

[70Bronco]

I just noticed there is no gasket between the block and dizzy--I'm guessing there should be one. Here's the shaft. That white bushing looks worn.

 

[PP1RT]

Rebush your dizzy and adding a gasket should help.

 

[oldbee]

Agree with above but here's a thought, if an old dist. you cud have little ridges built up from the holddown clamp, if you moved timing a little u could be sliding on the ridges. Far out there I know, but possible.

 

[Yatzee]

Has anybody experienced a situation in which the timing changes when you tighten the distributor? I've never had that happen before. Get the timing set, tighten the distributor down, and it advances 20* at idle.

If this happens when you snug it there's only two parts that can move, the distributor body or the shaft. I doubt you're allowing the body to slip with the tightening clamp so that means the shaft is moving. If that's the case it is caused by the helical gear engagement between the distributor shaft and the cam gear. There are only three possibilities with this scenario, the gear is worn, the gear has shifted or the distributor shaft is twisted. 20 degrees is a $hit load of change so the gear must be dropping lower on the cam gear or there's severe wear in this area. It is possible that your shaft is bottoming in the oil pump fork shaft. Maybe time for a new distributor.

 

[AR67GTX]

Mine usually shifts as I tighten it down - but not more than about 2 degrees. I have to apply a little windage when timing it so that it comes out right.

 

[70Bronco]

Mine usually shifts as I tighten it down - but not more than about 2 degrees. I have to apply a little windage when timing it so that it comes out right.

After playing with it, I got it to shift much less when tightening, but more than it should. Im going to get a gasket and replace the bushing and it should be better.

 

[HT413]

Like AR67 above, mine shifts about 1-2 degrees when I tighten it down I've noticed. When setting 18*, turns out more like 19-20*.

 

[AR67GTX]

Yeah - I think mine reads a little higher when tightened. Seems it's always a bit more than I intended so I have to loosen it and pull a little out.

 

[66Satellite47]

Take a good look at the drive. The slot gets worn.

 

[70Bronco]

Does anybody know where I can get a new bushing? Mine is nylon with a pin through the middle of it. Local auto parts store made a phone call and came up empty. They had brass ones with no hole in them. Looking online, but coming up empty thus far.

 

[HT413]

There's a member that rebuilds distributors, I bet he has them.

 

[HT413]

I hear @HALIFAXHOPS is the man.

 

[oldbee]

There's a member that rebuilds distributors, I bet he has them.

Halifaxshops(?)

 

[oldbee]

HT ur right!

 

[SublimeSixpack]

The distributor body has two metal bushings in it (one upper and one lower) but that piece you're referring to as a bushing is a spacer. I've never seen any side wear on them before. What is making contact with it? I know they get a bit brittle with age and can crack if you try to re-pin them, but that wear on the side is weird.