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Checking distributor shaft wobble

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wkilleffer

wkilleffer

Jedi Knight
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I spoke with some people, including Joe Curto, about the carb trouble I'm having, and they said to check the shaft wobble on the dizzy before trying to adjust the carbs. The dizzy had some trouble with frozen weights when I cracked it open the other day, and Joe said that can be a sign of other trouble, like a worn out shaft.

Is that checked by wiggling the top of the shaft that's inside the dizzy cap? I can see how even a small amount of wobble could keep the points open too long.

A new distributor is kind of pricey, when they're even available. Joe mentioned putting in an electronic system to prolong the life of the existing unit. He said a Pertronix system would work, but that a Crane would be best as they aren't affected by shaft wobble. Vicky-Brit also has a Flame Thrower distributor that looks like a new dizzy with Pertronix innards.

I'm a little wary of electronic systems, but am open-minded when it comes to keeping the car running. Any advice or suggestions would be appreciated.

Thank you,
 
To check the shaft wobble pull the Dizzy out of the engine. Just losen the single bolt on the clamp underneath it then lift straight out.

Now you are in business. The shaft bearing can now be checked just by moveing the housing from side to side.

You may wish to mark where the Dizzy is mounted on the plate first. If you reinstall with the marks lined up you will not have effected the timeing at all.

Oh yea, this is a good time to clean things up and make sure all is well in the Dizzy, much easer to work with on the kitchen table where it is cool.
 
Like Jack said, the best thing to do is pull the dizzy for examination. Remember that the part of the dizzy that the rotor goes on is a separate part from the shaft supported by bearings... it's supposed to move, that's how the centrifugal advance works.

Another option for the B-series engine is to fit a used Nissan Sentra distributor (1980-1984). You'll have to do a little modification to its mounting foot, and you may have to buy a new vacuum advance canister, however, it's a fun project that will give you a reliable electronic ignition.

Of course, Pertronix is always an option but if you've got serious problems with your Lucas dizzy, the Pertronix won't fix the root cause of the problems you're having. If you fit Pertronix you still need to go through the Lucas dizzy and make it right.
 
Thanks to both of you for your replies.

So with my dizzy out of the car, shaft in one hand and body in the other, if it moves radically from side to side, there's a problem?

It needs a better cleaning than what I was able to give it. How do you take it apart to the point that the weights can be taken out of the body?

Provided a suitable donor can be found, the Nissan Sentra dizzy idea sounds good. What do you have to do to its foot to make it fit, and what sort of electrical hookups are required?

Thank you once again for your help,
 
Yep, should be no movement side to side, it is a bearing, slop should be non exhistant really.

To take it apart start at the top and work in, lots of nuts bolts and such. Take a look at the book or take lots of pics and notes.

May I suggest you check with Tony for a good Dizzy if yours has problems. Used ones are not a lot and they last a long long time.
 
For info on the Nissan (Hitachi) dizzy conversion go to:
https://www.planet.eon.net/~chichm/
and click on the Tech Pages. You'll find a link to the page on converting the Hitachi for A- and B-series engines. Most of the work can be done with a hacksaw and file. Electrically, two wires come out of the Hitachi dizzy. One goes to switched +12V to supply the electronics, the other goes to the coil (-) terminal and replaces the old points connection. It'll make more sense after you've been to Marcel's web site.

To dissect the Lucas dizzy you really just need to read and follow the steps that are probably in your manual. There should be a screw in the center of the dizzy shaft under the rotor. You remove that screw to extract the dizzy cam. Needle nose pliers can be used to hook/un-hook the springs. This will allow you to free up the bob weights and clean up the inside. This is all from memory mind you... be sure to check your manual for a more detailed and step-by-step set of instructions.
 
[ QUOTE ]
For info on the Nissan (Hitachi) dizzy conversion go to:
https://www.planet.eon.net/~chichm/
and click on the Tech Pages. You'll find a link to the page on converting the Hitachi for A- and B-series engines. Most of the work can be done with a hacksaw and file. Electrically, two wires come out of the Hitachi dizzy. One goes to switched +12V to supply the electronics, the other goes to the coil (-) terminal and replaces the old points connection. It'll make more sense after you've been to Marcel's web site.

To dissect the Lucas dizzy you really just need to read and follow the steps that are probably in your manual. There should be a screw in the center of the dizzy shaft under the rotor. You remove that screw to extract the dizzy cam. Needle nose pliers can be used to hook/un-hook the springs. This will allow you to free up the bob weights and clean up the inside. This is all from memory mind you... be sure to check your manual for a more detailed and step-by-step set of instructions.

[/ QUOTE ]

For whatever reason, Marcel's website no longer has this file. But it's probably just as well, even though it's a very interesting idea.

If my dizzy's not in bad shape, I'll go the route of Crane or Pertronix.
 
Well, there's wobble, so I'm looking to get another one. Hopefully a good used one from Tony.
 
Tony is a great source, how bad is the wobble?

I see bushings are not really available but bet a generator/starter shop could fit one.
 
[ QUOTE ]
Tony is a great source, how bad is the wobble?

I see bushings are not really available but bet a generator/starter shop could fit one.

[/ QUOTE ]

Yes, he is, but only if he answers your email /ubbthreads/images/graemlins/wink.gif

The wobble's enough to notice and cause the points to be able to open wider thant they should. It's not a consistent wobble either. One of the four corners of the cam opens wider than the other three. The cam isn't worn evenly either.
 
William - if you don't get an answer via email - send me a PM...I get so many emails that my filter tries to kick out the spam & sometimes gets good mail...make sure there's something in the subject line about MG's or car parts.

& I think I answered your email within 12 hours....hehehehe
 
Oh goodie, we found the problem.
 
The least expensive quick fix would be to visit eBay and find a suitable used Lucas dizzy. I'm not sure which dizzy is correct for a '74 B but you aren't 100% locked into that exact model. The A and B series engines take the same size dizzy bodies so you can use just about any one of them.

I'm sorry Marcel's links are screwed up. He's created a curious infinite loop by redirecting visitors away and then back to his tech pages. I'll email him. In the meantime...

You can find out more about your car's dizzy by going to Marcel's tech pages at:
https://www.starchak.ca/
and downloading the dizzy database. Look up your dizzy using the 5-digit number you'll find stamped on the case and then find similar advance curves that will allow you to just drop in a cleaned up dizzy.

I'll see what else I have on the Hitachi. The conversion is really as simple as cleaning up the used unit, moving a Lucas drive dog to its shaft, and modifying it's foot to either bolt down to the engine block OR modify it so the Lucas dizzy clamp will grab the Hitachi body.
 
I had a dizzy shaft wobble in my 73B and could not get stable timing or idle. Put in Crane electronic ignition and viola problem solved. This is probably your cheapest reliable option.
 
[ QUOTE ]
William - if you don't get an answer via email - send me a PM...I get so many emails that my filter tries to kick out the spam & sometimes gets good mail...make sure there's something in the subject line about MG's or car parts.

& I think I answered your email within 12 hours....hehehehe

[/ QUOTE ]

Yes, you did. Sorry, couldn't resist a bit of a joke.
 
[ QUOTE ]
I had a dizzy shaft wobble in my 73B and could not get stable timing or idle. Put in Crane electronic ignition and viola problem solved. This is probably your cheapest reliable option.

[/ QUOTE ]

Does it matter if the cam that the points block rubs against is worn? That could be another cause of inconsistent point gap on this dizzy. The wear doesn't look even.

If you don't mind me asking, how long is a unit like this supposed to last, and how easy/difficult was the installation? Also, where did you mount the black box?

Thank you,
 
If the dizzy cam looks uneven it may or may not be wear. I forget the term but some dizzy cams have a modified profile and I forget why. However, I think all the cams lobes should look the same relative to each other (as long as we're not talking about air cooled VWs). If one lobe looks very different from the others that may indeed be a wear problem and it would certainly affect idle if nothing else.

How long should a dizzy cam last? A long time if it's properly lubed. If this is the original dizzy in the '74 listed in your profile, it has certainly exceeded its warranty.

The Crane/Alison ignition is great. I ran one for years in my GT6. They are generally long lived and the only detraction I can think of is that you have the external box to mount somewhere. They are easy to install (without taking a lot of time). I'd still be running the Crane in the GT6 today but I made the mistake of getting it wet while washing the engine. I killed it. I now run a Pertonix on the GT6, mainly because the entire unit fits under the dizzy cap. Both aftermarket ignitions are fairly imune to the wear in the dizzy... to a point.
 
[ QUOTE ]
If the dizzy cam looks uneven it may or may not be wear. I forget the term but some dizzy cams have a modified profile and I forget why. However, I think all the cams lobes should look the same relative to each other (as long as we're not talking about air cooled VWs). If one lobe looks very different from the others that may indeed be a wear problem and it would certainly affect idle if nothing else.

[/ QUOTE ]

It doesn't look like the wear has made a huge difference. Just that years of points blocks rubbing, some with questionable lubrication, have taken their toll on it. No one would mistake it for brand new.

[ QUOTE ]
How long should a dizzy cam last? A long time if it's properly lubed. If this is the original dizzy in the '74 listed in your profile, it has certainly exceeded its warranty.

[/ QUOTE ]

The date on the dizzy is 2/74. No one would mistake it for new. If there is uneven wear, it's not a radical amount. Maybe not even enough to have an effect.

[ QUOTE ]
The Crane/Alison ignition is great. I ran one for years in my GT6. They are generally long lived and the only detraction I can think of is that you have the external box to mount somewhere. They are easy to install (without taking a lot of time). I'd still be running the Crane in the GT6 today but I made the mistake of getting it wet while washing the engine. I killed it. I now run a Pertonix on the GT6, mainly because the entire unit fits under the dizzy cap. Both aftermarket ignitions are fairly imune to the wear in the dizzy... to a point.

[/ QUOTE ]

The wobble isn't huge, at least to me. I didn't check it with a feeler, but it looks like the normal .015 could be opening as wide as .020 when pushed that way. The points are always allowed to close.

Would a wobble like that be too big for a Crane or Pertronix to handle? The Pertronix would be great due to fitting everything inside the dizzy and it's less pricey. I'm pretty determined to go electronic. Its consistency might help with keeping the car in proper tune.

Thank you,
 
The wobble you're seeing is much more of a problem for the dizzy when the points are installed as the points spring is always pushing on the cam. With Pertronix or Crane the ignition triggering parts put no load on the dizzy cam. Either system should handle what you're describing.
 
Well W Killeffer,I am a bit late with this info.However, if you want to see Dizzy shaft wobble just fire up the engine let it idle and watch the timing mark jump around using a timing lite.If it doesnt jump around there is no wobble.If you want to easily correct a worn Dizzy,with excessive shaft wear [Wobble]install a Pertronics.---Fwiw-Keoke
 
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