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MG TD TF 1500 - Basic help

My MG mechanic of many years died in the last year. I have realized that it is now time to take the plunge and do most of the work on my TD (#0533) myself. I have the basic repair manual put out my MG on the car but it seems pretty obscure in some of their descriptions and a bit out of date.

Basic car data:
Shorrock supercharger with single SU carb
stock engine except for 3/4 race cam
standard head
4.1 rear end

I could use a hand on the following to make sure they are correct or at least in the ballpark:
points setting 0.012
plug gap .025
timing (I only have a timing light not a static tester) 5-10 BTDC
The differential and gear box have never had their oil changed since I had a rebuild 12 years ago. Should I leave alone or change it? Levels are fine.
All I see is confusion about what oils to use in the rear end and the gear box any definitive answer and where can I get it...NAPA?
The brakes have silicone brake fluid and work fine, so i was going to leave well enough alone.
It's interesting that I have had the car for 14 years and have put off much of the basic stuff, really doesn't make sense. Although I have a shorrock supercharger that I have done the work on because my mechanic was afraid to touch it..go figure!

I have never really messed with a basic tune up on a car before, so I am approaching this with a bit of trepidation.

Thanks in advance
Rob Silverman

The points & plug gaps will work, but the rest of the world got beyond those tight clearances before WW2. Opening the points will reduce the dwell, but you won't really notice any difference. I just closed the gaps on my wife's plugs from my usual .035 down to the .022 called for in one reference to observe any difference. The larger gap will command higher voltage and not foul as easily, but it may miss easier (like points fouling and decelerating). When checking point gap, the color is more important than the gap (especially supercharged)! Wife's '52 TD is running a new Eaton Magnacharger, so we're on the same page here. Damn thing started squealing today so it seems like a bearing in a new supercharger took a dump! Maybe I should've put my old Shorrock on it instead of investing $2500 in a new Moss blower (just slapped a Marshall-Nordec on her '50 TD today, too!). Bottom line, I wouldn't go tighter than what you set your goodies, but you can about double the gaps and not notice any problems. A Briggs & Stratton is more tempermental than this old tractor engine.
The 5-10 BTDC sounds conservative enough, but MG specced out ZERO degrees advance. Notice that there's only one notch on the pulley and just a single pointer??? They had ZERO advance in mind at idle. I disasembled my distributor wondering if a spring on a weight broke since there was sooooooo much slop, but no, there's just lots of slop! Guess they weren't too concerned about timing. I've read where some look for a max advance of about 25 BTDC on supercharged engines. I printed out a set of degrees 5, 10, 15...30 and marked a new pulley for another one of our MGs to use with a timing light. I like to be a bit conservative, so set it for 0 degrees, because my wife does not race NASCAR and doesn't need every horsepower she can get; it is bad enough she winds it out and burys the tach well past 6 grand before shifting!!!
You might drain the tranny & diffy lubes and look for the silvery aerodescent swirling fines in the oils. The lubes don't really disintegrate, but there's no sense circulating microscopic metallic particles. I run a hydraulic business and it is amazing how oils can settle out contaminants over a period of weeks to restore claritiy (nondetergent has its advantages). Throw some new oil in for a couple of bucks for insurance, or let the old stuff settle out over the cold weather in a jug with magnet and throw it back in if you're a cheapskate engineer like me. I drain ATF from my vehicles and swap it out routinely; about the same as replacing it with new without the expense. As for weights/grade/makes of lube, something thick like 90 weight or multiviscosity whatever (check some referncees if you like) just make sure it is slippery and topped up. (Hell, I watched the Magnacharger oil level like hawk and it took a dump anyway).
As for brake fluid, my buddy SWEARS the old Brit cars need Lucas original brake fluid rather than the new stuff to preserve the old rubber. It's worth looking into! I can't argue with him, but I just don't follow his advice either. With 8 wheel cylinders and 2 master cylinders to maintain, maybe I should?!?! I can't believe with trillions of Lockheed cups installed over the decades, I can't just ask for 3/4" or 7/8" cups without the usual "Huh? Duh? Nope!"
Anyone that would take on the installation of a Shorrock blower should find tuneup an absolute breeze!
jrn Northrup

For $15.00 you might just use 'new' lubricant in the diff and tranny.... You can go modern with Redline MT 90 or follow the good old owner's manual....90 weight gear oil.

One word of caution about brake fluid,,, DO NOT mix any other brake fluid in with the silicone brake fluid ,,,, If you have silicone in there now, stay with it,,, they are not compatible at all,, mixing it will cause large scale problems,,,

Steve Wincze

Thanks Guys,
I appreciate the help. Now its time to go to NAPA and get some parts/oils.

One last question, I do you guys lube the distributer cam with a thin layer of grease and put oil (scant) down to the advance springs and weights when you service the points? My manual talks about doing that, but I don't want to make a mess of things.

Rob Silverman

Yes...I follow the lubrication chart in the back of the manual/service book.Go lightly.... also the grease fitting on the generator.... (I cut a new piece of felt when I got it back on the road, as the original was all but gone....)

This thread was discussed on 16/09/2009

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