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yesterday had the hood open with the engine running and noticed the top of the dizzy moving round a lot. Is it repairable or do I need a new one? It seems to run good but I think it should not move around. 235 53 3100 root

The one on my truck used to bobb around like that and I believe it is quite common. This was at idle of course.

" . . move around . . "

Bobbing up and down, or rotating?

Rotating is normal - it is moving to adjust timing (vacuum advance).

Bobbing up and down - it should not be noticeable, if the distributor attachment collar is tight/good.

The dizzy is moving in a elliptical motion at idle with no vac. root

You have a bent distributor shaft. It's not a terribly bad situation, as a lot of old stovebolt distributors do that, but if it concerns you, take the dizzy apart and have someone mount the shaft in a lathe and use a dial indicator to locate the bend. Then straighten it carefully and reassemble. I've done that several times on small block V8 distributors.
Jerry

Lifetime reman. http://www.oreillyauto.com/site/c/d...tor_1487579_2546&keyword=distributor

I have seven distributors sitting on my bench right now and all of them have a slight wobble to them. Some more pronounced than others. If you take it all apart you can roll it on a flat surface and see where the bend is, then straighten it. I wouldn't do anything if its running okay. If it were too bad, your points gap would be erratic.

Deve/Jerry: Seems like it would put stress on something if you leave it alone? Would wear something out? No? Yes? Maybe?

I would never leave it alone if I hadn't seen all seven of mine wobble. I am not sure the cause of it. They do not get grease as often as they should due to poor design as much as an owner who doesn't give it a turn now and then.

I hate to recommend pulling the dizzy, taking it ALL apart and cleaning everything, straighten it and put it back in if its working fine. Also, I do not know how good the dizzy rebuilders are these days. Will you get a replacement that wobbles too?

Someday I will look into this properly and see if there is a way to add bearings high and low inside somehow to reduce the looseness inside the shaft housing. But I really do not know how they get bent.

Since the housing relies on its contact with the block to provide a ground for the points, any wobble will eventually interfere with the block to distributor fit and result in intermittent ignition problems. It's a simple fix- - -just straighten the shaft. You'll need something more accurate than a calibrated eyeball, however.
Jerry

Would the vacuum-advance/distributor-to-block clamp provide a good ground?

http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0619.html

It is unlikely the shaft is bent when the whole housing is wobbling.
I have seen this many times and believe the gear on the cam is not running true, putting uneven pressure on the distributor gear.
On a engine that does this I have tried a known good distributor with no change.

It's still a moving part, and subject to grease and dirt contamination. With the housing wobbling, even the vacuum advance bracket contact can become unreliable.
Jerry

Maybe that is why my engine with a Pertronix unit stopped missing at high speeds after I ran a ground wire from a distributor-cap clip to the head.

Some vacuum advances have a brass ground strap to ground the distributor, but some don't.
I have seen several engines where the distributor needed a ground wire.

If a ground wire is added (good idea, BTW) use a piece of high-flex wire such as what is used on multimeter test leads. The constant flexing caused by the motion of the vacuum advance will metal-fatigue the wire strands and cause them to break inside the insulation. That's also a good idea for the wire from the coil (-) terminal to the distributor.
Jerry

Meter leads are 18 gauge and I am having a heck of a time finding insulated flexible wire in red and black other than the 18 gauge. Anyone know where this sort of thing comes from that we can get in 10 or 12 gauge?

Look for 10 and 12 gauge silicone flexible wire. I see Amazon shows 10ft for about $10 or dollar per foot.
Common use is in speaker wire. This stuff uses more strands of finer size then normal automotive wire.

In red and black?

Yes, but if you have a local high end automotive sound shop in town they likely will carry other colors.

I live in Oz. I have to order everything in. That is the issue.. I can't seem to find a place that carries it in the proper gauge. Not sure how Silicone would hold up under the hood. The multimeter leads are a pvc hybrid. I would just cut some leads.. they are super cheap at $1.50 a set, but the gauge is the problem.

Silicone Flexible Cable (150°C - 200°C)

Yeah, not for under the hood. The water temp alone is 180 so you wouldn't want it touching the block. The point is, high flex wire is a non-issue because it's not readily available. It's obvious why we use the automotive grade wire we do. I have adjusted my thinking about the AWG gauge that I use. I err on the side of caution more these days. Thanks!

That would be 300 to almost 400 degrees Fahrenheit

Sorry I did not convert to Deg Fahrenheit 302-392 Deg F-.
Keep it away from the exhaust.

Now all I have to do is find a website that sells this stuff. Thanks for correcting that.. totally spaced that one! I did notice that most of them are voltage rated at 30-300v. That is American Voltage. LOL!

To go back to the OP first question. The "wobble" you observed. Can be caused by a bad cam, a bent dizzy shaft and...by a missing spring and felt/fiber washer under the grease cup. Make certain the fiber washer and spring are in place to take up the clearance between the housing and shaft. Replacement gears can be found, and may make the wobble a bit less. One of the members has a very good blog/post on how to tell what gear to what cam. And it does matter. Some one will know who the blog poster is. Nice site and a very good read.

Pre68Dave's Blog ( http://chev235guy.blogspot.com/ ) is what you were thinking. Its important you don't use a 216 distributor in a new style 235/261 engine. The metals are different. Not sure if that causes wobble.

If you run your distributor in a normal shop drill below the gear, you can see clearly what is happening with your distributor. If it wobbles at all, it's the shaft. If everything runs true, then you can suspect maybe a bad cam gear, OR a worn cam bearing set which would also cause this.

Steve has good advice above. Its very important that you have that fiber or nylon cap that rubs against the shaft with the spring providing pressure.

It not not just 216 vs 235.

It is the date: sometime in 1954 the metal changed (cam and distributor drive gear): cast vs steel (in the 235s and 261s).

So you have to careful using pre-54 235s distributors (and some 1954 235 distributors) and maybe early 1954 261 distributors in later 235/261 engines?

Thats more accurate Tim. I have two of them that I need to get new gears for. I wish I understood the real issue. How does this incompatible gear affect the cam? Is there a longevity issue? Does the cam wear faster with an incompatible gear OR does the distributor gear wear faster? With the wobbling issue with a perfectly straight shaft, meaning the cam gear is not running true, what IS the solution? Are cam bearings not wearing even, thus causing this? Dave is kinda busy these days, so I hate to bother him more than I already do! He is really the guru on this issue.

All good questions, Deve.

Since all my vehicles are 54/55 the distinguising characteristics of the cam and the distributor gear are of interest to me.

Dave has information on his website:

http://www.1954advance-design.com/Web%20images/235-cast-steel-cam-gears-pre68dave.png

Other illustrations (I hope they display)

I've seen all this and it doesn't change the quandry...

The gears are clearly identifiable by the chart you showed, but also if you sandblast them. The later models gear comes out regular steel colored, while the older ones come out with a copper or brass color to them. But the gears are not thinner, nor are they pitched differently. So the questions above stand. The cam can have a thinner gear area but the structures are the same. So a thinner gear would simply have a more wider gap before the next feature. So, call me thick, but I am still confused as to the ramifications of running an older gear on a newer cam.

Sorry, Deve, my simple understanding is that mis-matched metals causes unacceptable wear (in one of the combinations). I see/read no difference in the gear teeth dimensions.

I simply try to get a distributor gear and cam match.

It is interesting, I have seen 216 distributors(steel gear) used in 235's with cast cams where the gears were torn up bad. I have also seen the same combo work for years with no problem.
I feel it is best to match distributor and cam material.
The only mismatch I know Chevrolet approved of, and sold as a replacement for all, was to use the 235 distributor with a cast gear on all cams. Go figure.

Another interesting anomaly is that the earlier year distributors have a very sharp cut to the lobes. There is no rounding at all. Before I looked at a few I would have shrugged it off as wear, but nope, sharp hexagon shape as opposed to a more rounded one. Seems that could cause dwell issues.

I would think that sharp lobes would give more coil saturation time and less point arcing. The down side would be greater stress on the point arm and spring and a more pounding effect on the contacts. Personally I don't want a distributor to move around at all, even if by design, and I want to be able to walk in any parts store and buy over the counter parts at a reasonable price. That pretty much puts the HEI at the head of the class. The fact that I drive my old cars/trucks on very long trips and have numerous metal working machines most likely influences my line of thought. Picture of my 37 Buick straight 8 with machined down Olds HEI and cut down Chevy distributor shaft. Works perfect.

http://s32.photobucket.com/user/coilover/media/Dar%20Dog%20HEI%20003_2.jpg.html