The Stovebolt Site Forums The Shop Area Engine Shop Loose distributor?

I've been struggling for a few years to make my shiny new 235 run as smoothly as the old original 216 with cracked block. My latest troubleshooting technique is to compare potential problem areas between the sweet running 216 on my 41 Chevy sedan and the 235 in my truck. One detail I found is that the distrubuter on the 41 sedan sits as snug and tight as can be but still advances as it should, while that on the 235 wobbles from side to side. The 235 has an unknown history and I suspect is more worn than it should be, but the distrubuter looks fresh. The housing shaft is 1 1/16 inch, the hole in the block probably 1/16 inch larger, and it seems that the only thing holding the shaft in place is the flat plate that also mounts the vacuum advance. The hole in that plate is noticeably larger than 1 1/16 inch and seems not to be intended to eliminate that wobble.

The rotating shaft in the distributor seems to be fine, no extra play there, but it would seem to me that a distrubutor should sit fairly stable. Have I reason to be concerned?

Karl

The biggest concern with a loose-fitting distributor is the possibility of getting an intermittent ground. You could, and probably should run a ground wire from the distributor housing to the block. Since the housing is constantly in motion due to the vacuum advance, use a piece of very flexible wire, like the test leads for a voltmeter use. Regular primary wire will get fatigued and break pretty quickly. You could also press a sleeve of exhaust pipe tubing over the distributor housing and machine it to a closer fit with the hole in the block.
Jerry

Karl, if the wobble that you are describing is occuring while the engine is running, you might want to check the grease cup on the side of the distributor that it has grease in it and maybe try turning it in some. Mine had a pretty significant wobble that I was able to significantly reduce in that way. Also, there is a small plastic washer that protects the distributor shaft from the spring in the grease cup from rubbing on it; make sure that it is there.

Thanks, Lee! You too, Hotrod, you are the go to guy! I did clean and refill the grease cup while the dizzy was out, and everything is still there and working. There was some pretty old grease in it though. The distributor is back in the motor and it fired right up yesterday, it runs much better than in a long while. But it is still a lot looser than that in the 216.
I was surprised to find that the point gap is a couple of hundredths wider on two of the six nodes. Not a huge difference but still...

Have you confirmed that the distributor is the right one one for the year of your engine? And that the advance and other parts are correct. It is remotely possible that your setup has been assembled with different parts and made to work. If the diameters seem excessive, then something may not be correct, causing or contributing to the wobble.

Yes indeed, Mike, I do suspect that this 235 is a strange collection of well-used parts. The question would be if there is a difference in the shaft size for dizzys for a 235 and a 216. Comparing the distributors from the 216 and 235, the main bodies (and the cap) are different sizes, but the mounting shafts are the same size. I am considering dropping in the old 216's distrubutor to see of it makes a difference. The one from the 235 looks more fresh, but maybe it is not the right one either. Or just not as fresh as it looks.

You can check the numbers on them. I found a site but can’t seem to get it posted. I think the taller caps are for a 235

216 and 235 distributors will bolt in and run the engine more or less interchangeably, at least for fit testing purposes. If you're getting point gap differences between lobes, the ones with the smaller gaps are showing wear on the cam. A one-degree change in "point dwell" (gap) changes the spark timing at the cylinder two degrees, so a measurable difference in gap isn't a good thing. It might be possible to mix and match parts between the 216 and 235 distributors to assemble one that combines the best parts of both of them. If you use the centrifugal advance parts like weights and springs from the 235, your timing advance should be correct, or very close to original. If you choose to use the 216 breaker cam, be sure to check the height of both parts. That piece determines whether a tall or short rotor and distributor cap needs to be used. Also compare the position of the breaker plates in their respective housings to see if you can swap housings.

I still think I'd do a little machining on the wobbly housing if necessary. Making a Frankenstein distributor from donor parts should be a last resort, mostly because of the fact that stovebolt parts in your part of the world are probably pretty scarce. Good luck!
Jerry

So Jerry, do you mean to say that if I drop in the 216 distributor it will work ok but the timing advance won't be right for the 235?

My hope is to get this 235 running well enough until the old 216 is ready to go back in.

If you can post the part numbers stamped on the breaker plates of both distributors, I can probably find information on the centrifugal advance specifications. There's also a possibility of a mismatch between the distributor gear material and the camshaft, so it might be a good idea to swap gears before using the 216 distributor. The shaft diameters are the same, IMHO, so a swap shouldn't be a problem.
Jerry

I think I saved some distributor parts years ago and if so they are in a box in the attic. If you know what you need I can look for you.

It's running ok now, I'm just going to let it be and drive it a while. But thanks Jon!

Karl