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MG MGA - Distributor clamping plate

Has anyone found a better part than Moss or a modification? I’ve replaced it several times and over time I find that the “ears” on each side of the bolt twist out of alignment and will allow the the dizzy to pop out of the clamp.

(thank goodness for the guy with the half restored Chevy Apache who stopped while we were stranded on the side of the road and had a 7/16” wrench so I could remount the dizzy after the latest jump out)
Tysen McCarthy

I still have the original one on my 62'; never an issue with it. Forget the cheap repro units and get an OEM one in good shape; there's one on ebay right now:

https://www.ebay.com/itm/133641659287

Moss does sell two different types, but for $18 why bother with questionable replacement parts.
Nick Kopernik

The issue is usually over-tightening. If you can't move the distributor with moderate hand pressure, then it's already tight enough. There is very little force on the distributor while running.
Steve Simmons

Make sure you have the clamping plate in the correct orientation. The bolting ears need to lay flat against the engine mounting surface, while the center part of the plate is raised slightly around the distributor base.

I may have an extra clamping plate. If I do, you can have it for the postage. Let me know if you want it.

Jim
JL Cheatham

Thanks everyone. I purchased what is referenced as the OEM clamp from Moss.

We will see how that goes.

Then back through the process of re-timing it.
Tysen McCarthy

Interesting. One thing I have learned from my MGA experiences is whenever possible try to find and use original parts. The parts generally require some effort to make functional and sometimes the original finish is toast but original parts always fit, something that can't always be said for some of the repop stuff that is available.
Bill Haglan

Reminds me of when I decided to fix up an old points distributor to use as a spare to carry around in case the electronic one I was using, failed.

The one time that I had to use it, I found that the engine would not fire up with the spare dizzy!

It turned out that the dog on the end of the distributors drive shaft was set 30 degrees differently to that on the electronic one and so the timing was just too far out for the engine to run.

Colyn
Colyn Firth

I've never had any problem with the cheaper clamping plate, as long as you don't abuse them. Fit the plate to the loose distributor first to be sure the clamping ring is actually round. Be sure it will turn all the way around equally easy, and tighten the clamping bolt with nut driver only.

When installed the offset ears will lay against the base casting on the engine with the clamping ring slightly elevated. install with the base bolts loose, until the distributor is in place and can be rotated properly. Then snug up at least one of the base bolts so the clamp will not move. Remove distributor, tighten both base bolts, reinstall distributor, and be sure it still drops right in and turns freely.

After setting timing, tighten the clamp bolt gently. Imagine you are sill using the nut driver. If using a standard end wrench, pull torque with one finger only. The difference between free turning and tight so you can't twist it with two hands is about 1/2 turn or 3-flats of the nut. Do NOT over tighten it, as that will only distort the clamping plate for no benefit (and it may damage the clamping ring on the distributor body).
Barney Gaylord

This thread was discussed between 20/06/2022 and 07/07/2022

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This thread is from the archive. The Live MG MGA BBS is active now.