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MG TD TF 1500 - Rocker Shaft Assy

Back in the day - in 1974 when I first put the engine together. The friend I purchased the car from in bits wanted a fast MG and had assembled the parts to make it fast. Stage 4 tuning I believe were his words.
There were 2 fuel pumps and separate feeds from the tank. It had 1 1/2" SU carbs and a 4 branch extraction exhaust with an Arbath tail pipe. Larger TF valves had been fitted to the head with stronger springs and the Rocker shaft was fitted with Bronze Spacers instead of springs.
Over the years I have tried to de-tune those parts I can to put the TD back to STD. I want a TD that will last and not require constant tweaking and maintenance to keep it running, other than the usual minor stuff.

My question is - Is it OK to leave the rocker shaft spacers in place instead of the springs and washers found on a STD engine?
It has run fine like this for many years but I am now having some cam follower issues and will be removing it to check them.

This could all be because I have not been using Oil with ZDDP in it since coming to the USA in 1996. I did not realizing the "EPA" here had removed it because of catalytic converters.
To be fair I have run the car since 1974 and another TD for 10 years previous, and never had a cam or follower issue. I assume the Oil is the cause.
I am now using Kendal Oil but it is a little late I think.
I am taking the rocker shaft off and removing the tappets to have a look at what is going on.
I have a new long rocker shaft just in case it is also worn.
Assuming the clatter that comes and goes when starting the car and sounds to be coming from the tapper chest area, is a follower that has galled - Second Question - will it be OK to fit new tappets (of the right kind) to the existing cam? And bed them in as usual.

R. D. Jones

Yes...they actually keep the rocker arms centered over the valves better than springs do.
Gene Gillam

R.D. Tom Lange will probably be able to give you some good advice on the rocker shaft spacers. You mention 2 fuel pumps & 1 1/2" S.U.'s. These were standard on the TDC (Mk 2's) as you probably know, so if your TD is such then I'd leave them fitted. There are strong & polarised opinions on ZDDP on this forum which you'll no doubt discover as this thread develops. Certainly worth checking the length of the cam lobes (an indicator of wear) & the condition of the follower faces. The correct tappet run in procedure is critical & it's worth noting that the rocker shaft can easily be installed backwards. Ensure the oil feed holes are @ 1 o'clock when viewed from the front on reinstallation. Noisy tappets on start up are usual in a TD & should quieten down when she warms up. Check the tappet clearance on each of the valves before you pull the shaft apart. Also TD's came with either long or short rocker shafts & they are not interchangeable. Cheers
Peter TD 5801
P Hehir


I just last week, rebuilt my rocker shaft and have retained the spacers. Mine are in aluminium. They've been there since 1962.

Gord Clark
Rockburn, Qué.
Gordon A Clark

My guess is that you will find that the cam also has damage. The lobes could be pitted or scuffed, or the lift could be reduced by a thousand or so. In any case, I would be very suspicious of the camshaft.

The spacers are an old racing mod, and work fine if well set-up. See that the rockers have no sideways movement and hit the valve stems straight - I have Rocker Arm Specialists re-weld and re-shape my rockers when there is wear. Once rockers (and the cam, and the lifters) have lost even the slightest hardening, they are toast.

Tom Lange
MGT Repair
t lange

I recently rebuilt my Sunbeam Alpine engine and had the rockers, lifters and cam restored by Delta Cams. They do beautiful work for very reasonable prices, and their advice is excellent.

Kevin McLemore

When doing work on a rocker shaft it is a good idea to check the fit of the shaft in the posts. If it is loose, it is impossible to set the valve clearances accurately as the shaft can move up and down. This movement might even create its own noise. If there is evidence of hammering on the shaft, where it passes through the posts, there is likely to be unwanted clearance there.

In a vice, gently clamp the post lengthways along the large bolt hole only, with the shaft AND THE SPACER WASHER in place. This simulates the bolt being tight. If the shaft is loose, the spacer washer should be thinned down until there is "nip" on the shaft. Don't thin it down too much or the top of the post could break when the bolts are tightened.

I will see if I can find a diagram to scan and add to another post on this thread.

oTCagonally, Bob Schapel
R L Schapel

I hope this diagram clarifies my last post.

The shaft orientation used originally in an XPAG engine is probably OK but I always turn the shaft end over end so the oil supply holes to the rockers are underneath on the load area. This requires a new supply hole from the rear pedestal. I used to grind through the case hardening and then drill a new hole in the bottom of the shaft to get oil from the rear pedestal to the hollow shaft. However, shafts do break, usually inside the rear pedestal at the oil supply hole (whether using the original or my "upside-down" orientation). I now drill the new supply hole in the SIDE of the shaft so there is no weak point below. This necessitates the grinding of a groove inside the rear pedestal to get oil from the pedestal hole to the new "side entry" shaft hole. (NOT on the spacer washer side!)

Maybe this is all unnecessary but the "upside down shaft" is the way my road TC and my race TC have been for over 40 years. The "side entry" version has been in my race TC for about 10 years since I broke a shaft at that point.

oTCagonally, Bob Schapel

R L Schapel

A really nice bit of Aussie ingenuity Bob! Giving tired rocker posts new life. I like your style. (And no fencing wire needed!) Cheers
Peter TD 5801
P Hehir

Thanks Gentleman for the heads up on the spacers verses springs on the rocker shaft. No worries there.

I tried to take a video of the noise I get when starting the car from cold. You can hear the sudden drop in rattle at around 1.53 minutes into the video

I put it up on Mediafire.

I tried to keep the revs at around 2000RPM to splash oil onto the cam lobes. It almost sounds like one is dry?
I had just put in 9 pints of Kendal Oil so the tappets should have all been wet.
To my ear this sounds like a single follower is worn on part of its face and at startup it is not rotating. Once there is sufficient warmth and oil there, it does rotate and the rattle will come and go but nowhere near so pronounced.
Am I in the wrong ball park here? Could this be something else?
I will remove the tappets - inspect the bottom faces. (Keeping the locations and push rods together). I also have a dial gauge so can measure the cam lobes for height and similarity - to see if there is wear on the Cam. I presume they should all be the same height?
Could someone tell me the correct method of determining which cam I have fitted? Or point me to the archive which dealt with it? It has been a long time in and I am no longer sure.

R. D. Jones

It seems as Medisfire clipped the sound ???? Which destroys th epoint :)

Here is the YouYube version.

R. D. Jones

I don't know why this link won't post - could be a function of the BBS I guess.
If you search for "MGTD Tappet Noise" on YouTube you should find it though.
If this one does not work either.


R. D. Jones

By listening to the sound I guess it could be a sticking valve .

Gerard Hengeveld

Have you checked valve clearance? Sounds like one is very loose. Make sure you don't have a hollowed out rocker arm end that your feeler gauge bridges. You can remove the VC, throw an old towel over the works, and by sticking a feeler gauge between each rocker one at a time you find the exact location of the click. Sometimes you can see the pushrods rotate with the lifter as well. Make sure none of the pushrods are bent, and/or the ends are not loose. When you remove, number pushrods/lifters and keep in exact order as well. George
George Butz

Hi George
Yes, I have set the valve clearance and sure the rockers could be worn to give a false reading. I do have one of those clicker tappet adjusters (bought it back in 1968 – new, for a fiver) :) It should take into account any rocker wear when setting the gaps to 12 thou - hot. But I will check them when I have them off the car.
The problem is this noise comes and goes. It seems to me that a lifter is worn in one spot and as it rotates causes a change to the valve clearance. It sounds - with a stethoscope - to be in the tappet chest area (Cylinder 3) which makes me think it is the follower making the noise. When I start the car cold - it is much worse and as you can hear it then goes away at around 1 min 53 sec. Like it just stops - but it will come back as you drive. That’s why I think it is the follower with a bad worn spot.
I am about to take off the rocker assy. and remove the tappets to inspect them.
I understand about the importance of keeping everything in the same location - so no worries there. I have a wood block with the right sized holes in it to locate everything as I remove them.
I will post pics of the lifters (tappets) bottoms when they are out and what the measurements on the cam lobes shows. I understand Mort replaced his cam with the engine in the car for one of Lens roller cams. That may be the way I have to go.
I had hoped I could just get away with replacing the cam followers and breaking them in. But so far that don't seem to be what others here would do. Thanks for the comments. It is nice to have a sounding board here to get a pointer in the right direction, as I don't do this every year - thank God.
Rod Jones

Rod if you do decide to replace the cam I've just done it with the engine in the car. Difficult but not impossible. Contact me offline @ pjbm at & I'll pass on my notes on your proposed cam installation. Cheers
Peter TD 5801
P Hehir

This thread was discussed between 05/08/2014 and 07/08/2014

MG TD TF 1500 index

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