The Stovebolt Site Forums The Shop Area Engine Shop Distributor lateral movement in block

I have a recently rebuilt 56 235 engine in my 3600. Runs well and idles fine. For whatever reason I noticed the dist. wobbling in the motor. First I thought the shaft was bent but it isn't. The whole dist moves quite a lot in the block. It should have just a slip fit right? My only other car with a dist was an MG. IT WAS A TIGHT FIT. Let me know what you all think. Thanks Sharon

Stovebolt distributor housings turn in the block in response to the vacuum advance operation so they have to have a somewhat sloppy fit to avoid binding. As long as the shaft doesn't wobble or have side-to-side play in the housing that causes the point gap (dwell) to vary, a little slop between the housing and the block is no problem.
Jerry

No side to side play in the shaft. When the engine runs the dist wobbles. I'd have to see another engine run to if it wobbles too. Could someone run theirs and see if this happens?

I just went through this

In my case the clamp arm on the advance was to loose
...link...

That's one thing you can check if you have excessive wobble.

I did not see yours wobble at all DAD 50. I will go and check that clamp. Thank you

That is a video from a few years ago, no issues in that video

The wobble I just took care of recently
https://www.stovebolt.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=1081512#Post1081512

I'll pull the dist this weekend and check all those things. You have been a great help Thanks

Pre '68 Dave and Hotrod Lincoln helped me with my issue.


Your probably more experienced than me,
One thing I always do now before I pull my distributor is to put the ball on the pointer and note where the rotor is.

So when I go back together I put it back in the same place.

Some times the oil pump slot will move a little, so when you drop it back in you might be out of time.

I believe Sharon is talking about the whole housing wobbling in the engine block.
I have seen this in the past and have not come up with a good explanation for this.
I have tried changing distributors with the same wobble after.
The only thing I could come up with at this point is that the drive gear on the cam is not running concentric giving uneven side pressure in the distributor gear.
The only other idea I have is that the pilot hole in the oil pump that holds the lower shaft of the distributor is worn so it is not supporting the lower end of the shaft.
It seems I have seen this with a new pump also so that seems unlikely.

Just guessing because I've seen brand new distributors have a slight wobble in the block, while on other 235s none.

Perhaps the bore size of the hole where the distributor goes through the block is not as precisely cut as some of the other areas might be. So perhaps some distributors have a little more play between the body of the distributor and the block.

I've had 3 235s and one 261 and have worked on a few 216s.

Some distributor would have a slight body wobble while others didn't.

I don't remember it having any detrimental effect on the performance of the engine so long as the distributor wasn't binding in the block.

But that's just my humble opinion and may not be worth much. I've never researched it. But is an interesting topic to consider.

Maybe someone who has a couple of 235s laying around could measure the bore of the block to see how close they are in their measurments.

There are bound to be some +/- dimensional tolerances, both on distributor housing OD and the ID of the distributor hole in the block. Since the distributor isn't locked down rigid in relation to the block, some wobble is bound to be present when the tolerances max out. Unless there's a dwell variation caused by internal play in the distributor, it's annoying, but not critical.
Jerry

Best guess? The gear on the shaft and the gear machined on the cam have some combination of out of round. The forces are not great. You drive the pump and turn the dizzy shaft. You might even have some side to side slop in the oil pump. Add it all up and a "loose running fit" as I was taught and...a little wobble. Some more than others. If the pump is pumping, and the timing is stable, it would seem to matter little. I suspect the loose fit in the block is the real culprit.

I pulled the dizzy out and found no fiber washer and spring under the grease fitting. replaced these. No bend in shaft. repaired the looseness at the advance and dist point. Dist does not wobble now. It seems I have lost the advance feature of the vacuum advance. Ii has 16 inches of vacuum at the advance under throttle snap. maybe I just paranoid but I thought it moved the last time I looked. Maybe it doesn't move until you get it under good load while accelerating. Anyone second guessed themselves?

Looking under the hood, if you rev the throttle, the advance should move. If it doesn't, there is a problem.

What is the vacuum on the advance line at idle? It should be zero until the RPM is raised slightly. It sounds like your distributor vacuum line is connected to full manifold vacuum, not ported vacuum.

It's possible you have tightened the linkage up too much and locked up the advance unit. You should be able to turn the distributor housing CCW with the engine stopped and the spring inside the vacuum advance will return it CW when you release it. Forget everything you know about Brit cars- - - -a stovebolt distributor is SUPPOSED to move!
Jerry

I reads zero at idle. It is on the ported vacuum that it was on when I took things apart. I put a vacuum gauge on the ported line out of the carb and it reads zero at idle then moves when the throttle is opened. The advance tries to move but not until I manually twist the dist and give it some help. That is why I disconnected the advance from the dist. Still no movement.

It does move back on its own when twisted CCW.

OK- - - -it sounds like you've got a hole in the diaphragm. Use a long piece of rubber tubing attached to the distributor line and suck on the end of the tube like a soda straw. The distributor should move, and if you plug the end of the hose with your tongue the dizzy will stay advanced. If not, you've got a holed diaphragm. The old school leak test was to blow cigarette smoke into a vac advance and see if the smoke came out the dizzy side.
Jerry

Ok Jerry I tried what you said and the dist moved and stayed moved until I broke the vacuum. I do have Tom Langdon's carbs. I'm hooked to his ported outlet in the diagram.

How much vacuum do you get at the distributor at a steady 1500-2000 RPM? If it's over 15 inches, you should be getting full advance, but only at a steady cruise RPM. Snapping the throttle won't allow the distributor to move, or you might just get a little movement.

If you're running dual carbs, it might be necessary to Siamese both ported vacuum lines together to get enough vacuum to keep the advance in full CCW for cruise.
Jerry

I siamesed the both carb ported lines and it pulled 14 inches at 1800 RPM's. We live in Tucson at 2800 feet. I guess that alls well. Thank you Jerry

What carbs from Landon's are you using?

How many inches of vacuum at idle?
What is your idle RPM?

The Carter/Weber that he sells. I think Weber 32 DFT. 18 inches @ idle. 600 RPM's. We are about 3,000 ft.

Thanks, same as Motorcraft 740.

Supposedly, 18" at 3,000 is 21" at sea level. Yours vacuum looks good.

Here are the vacuum advance ports I connected-to. It ran smooth as silk.

Exactly as mine