Thread: 51 MG restoration.

Originally Posted by MikeB52

The vernier knob adjust total timing. Vacuum advance works independently and above what that knob adjusts.
As I turn the vernier full clockwise, the vacuum retracts into the distributor and the rotor disk rotates counterclockwise accordingly.
Turn the knob counter, and the vacuum advance housing moves out and the rotor disk rotates clockwise advancing the timing.
Dialed it back to 4’ and no more stutter or hunt.
Must have fiddled with it during my initial cleaning..
Runs smooth, and strong now.

I see that you found the timing pointer. I went out to my shop today to build bracketry to mount the front end of the Lamborghini Miura I'm working on on my rotisserie. I checked the TR engine I have, as I said I would, so I could tell you where the timing pointer is. It is as you show it to be. The vernier knob is usually used for quick, fine tuning of the timing. Set the timing with a timing light and turning the distributor then tighten the distributor locking plate. If you want to fiddle with it after that you can us the knob. You lucked out by having the updated ignition. It will save you future problems and provide a hotter spark.

Here's a question I have..Is that pointer and hole lined-up marking TDC, or is it lined-up on the ignition timing spec? Seems there is no scale. Most go at a few to 10 degrees before.

Anyway, On the oldies, usually parts have been changed. Nothing set in stone anymore.
If it runs OK, I usually give them 2500 RPM at least and advance it til it rattles or shakes.
Back it off til it's smooth. Good place to begin, IMO.

So, Mike...Them carbs are not quite so bad anymore, eh?

Originally Posted by sharptonn

Here's a question I have..Is that pointer and hole lined-up marking TDC, or is it lined-up on the ignition timing spec? Seems there is no scale. Most go at a few to 10 degrees before.

Anyway, On the oldies, usually parts have been changed. Nothing set in stone anymore.
If it runs OK, I usually give them 2500 RPM at least and advance it til it rattles or shakes.
Back it off til it's smooth. Good place to begin, IMO.

So, Mike...Them carbs are not quite so bad anymore, eh?

I do that too. Use the timing mark as the initial setting then go by ear. That makes up for timing chain/gear wear.

Man, you can get pretty anal on timing a distributor.
For instance, I would bet you can take those fittings of the vacuum advance and take away/add shims to change it's effect.
As a youngster in the trade, I remember a few old shops having a huge cabinet with a crazy scale and adapters below. Lotsa switches. You would put a distributor in and set it all up.
Dwell (point gap) mechanical and vacuum advance.
You could see wear in the shaft bushings.
Such a crazy piece of old merchandising. I suppose they worked, however.
Reckon they had no timing lights with an advance dial back then?

I had one of those machines way back in the seventies; bought it cheaply, never used it. I juncked the top (the workings) and still have the lower cabinet
part. I have sanding abrasives in it. Sharptonn, I don't know your name, mine is Tom as in Tom Du Jardin.

Yeah, they were masterpieces! Was it a Bear? Likely a Sun.

Mine is 'Tom don't call me late to dinner!'

It was a sun.

Family run shop back where I grew up had a Sun Distributor Machine. I used to take my Mallory dual points distributor out of my 327 and have them set up new points etc. They would let customers watch. It was really fascinating.

https://www.youtube.com/watch?v=c0ithHsZNVs

Just getting in. Gave blood tonight and that took two hours but my good deed.
That hole and pointer are tdc, period. After that, the vernier takes it by degree to get to your desired advance.
Manual predates timing lights I think as there is no discussion about using one.
When I did use mine it was as shown in my picture about maybe 8’ btdc. Explained lots, and yup the carb seems ok after all.
But I bought a kit and everything hehe.

If a carb is working, leave the thing ALONE!
That's how I roll!

So Learner! Got your PM's turned-on?