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MG TD TF 1500 - MG TF speed improvement

I seek guidance regarding a 1250 cc 1954 MG TF. Before going further, I should confess I am a mechanical neophyte. Although I know one end of a wrench from another, I am not always cofident about where to apply the wrench.

My basic problem is speed. The car is not fast enough at appropriate rpms for highway driving and I need to drive highways to get to some of the byways out of town. What recomendations does anyone care to offer on how to improve highway speed?

Can anyone offer me any insight on: (1) how to improve the output of the engine (or suggestions on replacemnent); and (2) experience with five speed gear box conversions?

On an unrelated topic, I have an issue with my clock. It has an electrical terminal on its back but no wire attached to the terminal. I haven't been able to find any wiring diagrams or reference material explaining how the clock was wired. I would appreciate any suggestions.

P. Hejmanowski


there are a number of modifications involving modern gearboxes, diffs etc which will accomplish what you are after and I expect that you will get advice on this bulletin board from many people in the US who can advise on what is best for local conditions in The Us and what is available there.

It sounds to me though that you may have not yet come across the continual hassels of running a +50 year old car. Rather than spend a lot of time and effort in modifying your TF, and not achieve what you are after, pehaps you might consider moving instead to one of the replicas. I am not refering to a fiberglassed VW or the like but to one of the properly designed and built copies of the TD/TF with modern running gear. I don't know what is available in the US, but there is a bloke up the road from me here in Sydney who sells a very attractive car that is like the TD/TF in appearance but has a modern engine, running gear etc. I understand that it is from a factory in malasia. I have not tried one myself but am told that it is very roadwothey, comfortable and reliable. It is certainly attractive and only a person familiar with MGs would pick it as not being original and it looks like fun. I presume that such vehicles must be available in the US.

The clock has a single spade power connector. From memory on my RH drive version it is a short red (power) lead at the back of the dash. Wiring colours on the LH drive could be different. i can't see the clock on the wiring diagramme, but I think I recall that the lead taps power from the "hot" side of the ignition switch.

All the best

Bill McGee
Bill McGee

The five speed is expensive, but nice but cheaper is getting a new rear end in the car. The TF was fine as it was but putting an MGA rear end in like a 4:1 can lower the RPM's and make it more highway worthy. The engine was designed to run at high RPM's as it was but I can cruise at about 65-70 in the 4000 range with no problems on my TD with the 4;1 rear end. It does not cost all that much to convert and you can get it done for about 1200 bucks or cheaper if you can do it yourself. THere are folks out there in the US that do this. My first suggestion is get ahold of someone in the local club and ask them.. There is much to learn about these cars adn the local clubs have all the knowledge. If you dont know of one, this site has a listing that you can find one.
TRM Maine

A numbers of our clubs members (57) have converted to the MGA 4.3 ring and pinion, some TF 1500s have done the 4.1 conversion. This allows a speed of over 65 at below 4000 RPM, great for expressways.

The 4-speed conversion is an alternative. but the same RPM as high with the 4.3 conversion

The engine was designed to run at RPMs greater than 4000 RPM although our US nerves were conditioned to run at 2000 to 2500.

I have cruised easily at 75 MPH on empty expressways, NO COPS, (TF 1500, stage 3 tuned, 4.1 rear end)

Don Harmer

Check out my listing on eBay for a 4.3 rear end fully overhauled:

Now gentlemen, if this is inappropriate given the post please let me know.

Dave Clark

Arizona 4.3 directed to someone in Nevada in need...I certainly find nothing inappropriate about that at all! Getting to stage 3 tunning will certainly help also. (small booklet readily avaiable for that) IMHO for the return those 2 mods are well worth the investment.
David 1500 / 4.3 / Stage III
David Sheward

Paul, I understand your "highway frustration" but please remember the TF is now 56 years old and was inutially designed as a "British" sports car for driving, quite fast, down English country lanes. Having said that, we now do use them on our faster and straighter hiways and the least expensive mod is the rear axle change.
The vehicle Bill mentioned is probably the ill fated Naylor & Hutson TF. I have seen the car and it looks good, running on relatively modern gear, so is set up for hiway speeds. The MG Enthusiast magazine shows it in two models. Suicide doors and the safety doors.
I have attached photos of both.
Don't bother with the clock connection, it rarely works for long even on the best restored car.

regards Ian

I Denton

The "other" TF with original type doors

I Denton

Bill McGee is referring to the TD2000, made in Malasia

Its pricy - around $50,000. Uses the same Toyota engine as the Lotus Elise, but considerably detuned.

But why bother? You've got a lovely MG. It was designed for 1954 roads and conditions. Don't expect it to perform with today's roads and traffic.

Lots of good advice for you in here, Paul. But remember, you're still driving a 56 year-old car.

Join an MG Club and get all the advice you will want - for free.

Gord Clark
Rockburn, Qué.
Gordon A Clark

Just to round off my previous response, I checked the wiring on the clock, it being thirty years since I did it. The clock is wired to the close terminal on the ammeter.

Ian is correct about the clock. However, should you wish to confirm this yourself, please note that after power is applied to the clock, it needs an impulse to start it moving. To do this, give the flat round spring-laoded knob on the back of the clock a sharp tap with a finger. Should the Gods favour you, the clock will then spring into action. the time it keeps though, as has been proven by extensive reserarch, has no correlation with the movement of any known celestial body. After an indefinite, but not long, period the clock will become bored with this activity and decide on a lie down. Reactivation then requires another impulse - often refered to as a "kick in the cogs."

Good luck.

Bill McGee
Bill McGee

The most knowledgable and ingenious Gordon Lawson has in my opinion the best idea for a TD-TF clock,,, Do a search for "clock repair/replacement",,, Very inexpensive, easy, and clever,,,

Steve Wincze

As original there was no fuse in the clock power supply. I would suggest installing a very low amps inline fuse, maybe 1 or 2 amps? Bill is right about having to pop the setting knob to get it going. Besides either method to increase gear ratio, make sure your car is running as it should. Check compression and make sure well-tuned, valves adjusted, timing and distributor advance working correctly, etc. You can gain a little power by raising the compression. Large gain in HP = lots of $ however. If you replace the engine with something else you have killed the value of the car- better to just trade for something more modern than doing that IMHO. George
George Butz

Paul, I have done the two things you asked about on my 54 TF. When I did the ground up a few years back I put in a 5 speed tranny and after a year or so of driving it I mounted a super charger to the engine. It will cruise at freeway speeds but it still is not going to accerlerate with todays modern cars. Neither addition was cheap and I did the installations myself. Changing the drive train to something more modern can be done but it requires custom fabricating and would be beyound what I would be willing to tackle.
At the end of the day the money spent towards making it keep up with modern traffic would most likely be better spent on buying a used econo box that would be safer for freeway driving. My suggestion would be to keep it in the slow lane, leave earlier, keep plenty of distance between you and the car in front of you, take the less traveled route and enjoy the ride.

Excellent advice, Len.
Gene Gillam

I have done much the same modifications as LaVerne with his TF. My TD has a M-N blower, a 4.3 set of differential gears and a Datsun 210 Skyhook 5 speed gearbox. I also stay in the slow lane most of the time and the engine just purrs at about 3000 to 3500 RPM. I would do it all over again knowing now how it performs without all the excess strain on the engine.
Installation of Jerry Austin's axle set is on the agenda for my car's annual Winter hibernaion in the basement.
Jim Merz

I drive my TD at just under 5000 rpm at 80 miles per hour by GPS, and at 4250 RPM at 70 miles per hour. All day, no problem. I stay away from 4400 rpm because the geometry of the engine lends itself to harmonics, no matter how well balanced the engine is. My only modifications are the 8.5 CR (due to the engine rebuild and the head needing skimming) and the higher rear end at 4.3:1. I like the original gearbox, and with the higher gears first is usable (although noisy!) and the car accelerates faster because first is usable longer. If I wanted to drive a smooth, five speed gearbox, I would buy a more modern car. My goal is to experience something from the 50s, and that includes the high RPMs and the slow synchros.

Dave Braun

I thank everyone for their comments and suggestions. This has been most helpful.

I am inclined to try the rear end conversion because it doesn't change the car too radically. After all, I like the car just the way it is. The problem is simply that I can't get to the neat backroads of Nevada without first exposing myself to the racetrack environment of the freeways leading out of Las Vegas. A little more speed minimizes the risk of becoming a hood ornament for a Mack truck.

Dave Sherwood- could I impose upon you for the title of the tuning booklet you referenced?

Thanks again for you collective help.

P. Hejmanowski

The simplest way to bump up the horsey power (basically what the stage II and III are doing) is to get the compression ratio up to around 9 or 9.5 to 1. This is usually accomplished by skimming the head. Check the thickness of your head and if you find that it's below 3" then it's probably already been done. Mines about stock so I'm guessing I'm running at about 7.5 to 1. Jumping up the compression will probably give you another 15 hp or so but let the experts chime in here. Cost is whatever your machine shop charges for the skim job, a new head gasket, manifold gaskets and your time.

Beware it could be one of those "while I'm in here I might as well" jobs.

Guess I'm in Dave Braun's camp, but the run up to just under 5K is a rarity. I'm running about 9:1 compression and 1305cc. Motors comfortably at 70-75 mph. Bud & Lazarus
Bud Krueger

LaVerne, I forgot to say in my previous posting that I also had the head milled (I forgot the amount)so that the engine now has about 8.2:1 CR. I wasn't looking for more power especially but mostly to take advantage of our higher octane gasoline compared to the "pool gas" used in England in the 1950's. I figured at that ratio, I was not taxing the bottom end engine parts but still getting a bit more push out of our Regular grade gas. As Dave B. points out, when we install the 4.3 gears in the differential, first gear does improve a lot. I was amazed at that but something I had not previously thought about.
Jim Merz

I have basically a stock 1250. Would that level of tune pull the 4.1 rear gearing or would I be better with the 4.3. I'd be interested in this as with 4.1 gearing over my current 4.875 would yeild almost 9mph at 4000 RPM I believe. That would be wonderful if the motor would pull it easy enough.
l rutt

Special Tuning for MG midget Engines.
They come up on fee-bay quite often. If you can't find a copy contact me off board and I can copy mine for you and snail mail or send scanned images.
hootersvilledavid "at" yahoo "dot" com
Rear end conversion is most common ...makes 1st gear usefull for something other than pulling tree stumps.
(hillclimbs were very popular when these cars were new, believe that was reasoning behind that low ratio.)
Super chargers are cool ...but you want to make sure you bottom end can handle it first (fresh re-build / good idea). and $$$ (I'd love to have one)
Couple other inexpensive and easy things that may help you pick up a few HP:
Jet-Hot treatment on exhaust manifold / aprx $150.00
Changing to Pertronics Ignition / aprx $100.00
Not that expensive and weel worth the effort/expense ..IMHO.

David Sheward


You could also go to the technical section of my website and download the WKF Wood 1968 Tuning Guide for XPAG engines. Very informative.

I second what Dave S is saying, the JetHot and the distributor refurbishment by Advanced Distributors enables me to take advantage of more advanced timing than possible with a worn out distributor. For that reason, I don't need the pertronix, as my points stay dead on with the closer tolerances.

Larry, in my opinion, in Florida you would have no problem with a 4.1:1 if you put in the CR of 8.5:1 and tuned the engine... consider your distributor as well. My engine is .060 over, which contributes to the higher CR.

Dave Braun


"A little more speed minimizes the risk of becoming a hood ornament for a Mack truck."

Do not feel you should kowtow to the bluff of such vehicles. A TF rules the road and all else must defer to it. Use the road with confidence as it is yours.

A few years ago crossing the Nullabor, I reveled in the delight of having road trains banked up behind me, waiting patientently (I presume) to get passed. If you are not familiar with the road train, let me say that the prime mover has more in common with a locomotive than any Mack. Of course, I must admit that on the Nullabor the straights are up to several hundred kilometres long so the road train driver has ample oppertunity to see you and make appropiate speed adjustment.

however, the point is not to be of a faint heart, in a TF the road is yours.

Bill McGee
Bill McGee

I.Rutt, & Paul: I have been running the 4.3 rearend in my stock TD for around 7 years, and it is perfect for my style of driving. It yields 60 mph at 3500 rpms, which is fast enough for me in this old car, which by todays standards is a death trap. I drive very defensively! As Dave B says, you now gain the benefit of a now usable first gear, and the car still has decent acceration and hill climbing ability. What makes it such a nice mod is that the engine is really free revving. I personally would not endorse the 4.1 ratio, unless you were using a blower, or some other means of significantly raising the output of the engine.
PLEASE examine your tires and make sure that they are not new looking OLD sheep in wolfs clothing, jusr waiting to come apart at highway speed!!
Steven Tobias

Dave B,

Would you please expand on your comment regarding the work done by Advanced Distributors.

James Neel


Interestingly, during the restoration I had my distributor gone through by someone else first, but for some reason they put in the new bushings, but left the shaft, and the new bushings were either NOS or the original bushings. The advance weights also came back stuck at no advance. At any rate, the distributor came back working worse, and prior to that rebuild I never had problems with the distributor pumping oil up past the bushings.

Advanced Distributors (no financial interest, but Jeff is a good friend) took my distributor (which was pumping oil up into the bowl, and then into the points, which then needed cleaning every 250 miles) and replaced the bushings for the shaft, pinned the bowl to the shaft housing (it was loose) replaced the shaft, freed the advance weights and set the springs for the state of tune of my engine, and put in new points and one of his specially made rotors.

Before the work, I could static time my car at TDC and it would run. After wards, I could static tune it at about 12 BTDC and fine tune it from there, without pinging. With the working advance I get better economy and power in high RPM low MP settings (remember, we have no vacuum advance on our cars) and frankly, made the car more powerful, drivable and made my engine rebuild complete.

Dave Braun


Thanks for the information. I have never had anything done to my distributor other than replace the cap. After the last rebuild in the early 80's the car has run well but now I think it is time to pay attention to things that will put me ahead of the curve mechanically speaking. From looking at the workshop manual it looks as if pulling the distributor is not a complicated project so when it warms up a little (unheated garage) I will go for it.

James Neel

Dave brings up a good point with the "advance weights and springs".
First year I had the TF it seemed a bit "doggie" on hills. Turned out one of my springs was broken and jambed in there. Did not have to remove distributor from car to clean up & replace springs.
An easy fix and made a BIG differance!
If I have learned one thing in the last 10 years from the experts on this BBS :
"KISS" definitly allpies to these cars!
Look first for the obvious silly /easy to fix things first.
I am still amazed when I look back at all the little things that were wrong with my car, when I bought it, that it ran at all!
David Sheward

This thread was discussed between 07/01/2010 and 10/01/2010

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