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MG TD TF 1500 - Rocker shaft spacers

When I assembled my TD engine back in 1972 the PO has assembled the parts to stage 2 tune the engine.
Part of that was bronze spacers between the rockers instead of the usual springs. I now note that after 46 years of use there is a bit of play between some of the rockers allowing them to move laterally. What would be a good rule of thumb for allowable play? I do have a set of springs and thrust washers in the event - but the bronze spacers help with the oil distribution better I think.
Rod



Rod Jones

Rod,
As a guess I would think 0.1mm but others will know for certain.
Regards
Declan
Declan Burns

Rod as long as the rocker pad is not missing any part of the valve stem, AND the push rod is not contacting the push rod tube I would not worry about it.
Len Fanelli

Thanks
Declan & Len, There is about 20 thou free float between 4 and 5. Which I did not notice in the past. Possibly due to wear on the bronze spacer. When moved by hand it makes a lot of noise. I was wondering if it contributed to the tappet clatter? Would removing the float quieten it down any?
I fear the big issue is the tappets have galled again in the last 4000 miles following a regrind and it looks like I will have to do something major to resolve it. The real problem is they do not rotate as they should. Despite doing the correct running-in process.

Rod Jones


Rod, as for the end play I would install 2 of the thrust washers you already have, and fit as needed.
Have you needed to tighten the valve lash? If so there IS tappet / cam wear.
Tappets galled AGAIN! Did you specify the regrind to be done on a taper to help rotate tappets?
Please E mail me for more camshaft options / information.
Abingdon Performance Ltd.
Len Fanelli

Hi Rod,
You will find that if you loosen the centre two rocker pedestals slightly, tap the pedestals towards each other, and retighten the pedestals, there will probably be less clearance on 4 and 5. You will also have more clearance on 2 and 3 and/or 6 and 7. The problem with spacers is that the bolts and holes in the pedestals are not a precision fit. The pedestals finish up in whatever position they are when tightened. In the past I used rockers with spacers and just made sure that when pedestals were tight, there was detectable end float on all rockers. I have now gone back to the original spring arrangement. I don't think a bit of end float (when using bronze spacers) results in extra noise. BTW, I believe bronze is the usual material for spacers, but I would think steel would work just as well.
Bob
R L Schapel

I agree with Bob. Steel spacers are available for the A-Series engines and many others too.
e.g. see
https://mossmotors.com/spacer-set-rocker-solid
Regards
Declan
Declan Burns

Thanks,
I guess as I have detuned my engine back to STD, I don't really need the solid spacers. I removed the 4 branch extraction exhaust and Arbath tailpipe and the two 1 1/2" SU's and dual fuel pumps back in 1980. In an attempt to keep the old girl on the road and not wear her out so fast. The boy racer wore off fairly quick :) I have a new rocker shaft and all the springs and washers that go with the STD set up, so could use a thin washer or two to take up any slack and keep the spacers in place.
With regard the cam and tappets I would like to fit one of Len's roller setups. Just have to convince my self I need to remove the engine and while it is out, do all the other work that a 45-year-old engine will need to have done. I have some fear that the head that was skimmed in 72 and had larger TF valves fitted, may be at the Max. If it needs more work now, the only option may be a thicker head gasket.

Appreciate your info guys.

Rod
Rod Jones

Manley Ford has the best ( custom ) head gaskets, with copper fire rings in standard thickness and .065" thick.


Len Fanelli

Rod,

You don't have to remove the engine to check the valves.

But before you do, you might want to do two compression tests 1)cold, and 2)hot (or warm), Chart the measurements. The delta between hot and cold will tell you if you are passing compression. But if cold values are below 130, you might have cause to worry. But it may not be the pistons or the rings,

TD head thickness new is 76.75mm (3.02"), TF is 75.16mm (2.99").

With the head off, lap the valves, replace the head and do another compression test. Again, check values against those taken before lapping the valves. If the low values are consistent with earlier measurements, only then should you consider fiddling with the rings or pistons.

For me. removing the engine is now a daunting challenge (didn't use to be!)

Gord Clark
Rockburn, Qué.
Gord Clark

Sound advice Gordon Thanks,
Same here - in the past this would be a no brainer but now at 74, it is what I would consider hard work.
To add to the misery, the paint is starting to spiderweb. Possibly shrinking. IFI take the engine out for work I should really do the paint job as well. This was cellulose enamel and at 45 years has done well.
IF I have to take the body off. I should also do the chasse
See what happens when you go to do your tappets and then things just all go to hell. Lol
I did do a compression test sometime back when up in Maine (Cold) :) It was not good - wet or dry. I had used a Harbor Faith compression tester and it gave unreliable results. I have not seen one for sale since then, so maybe it was Chinaeezium defective.
I will do another compression test, Hot and cold, and if there is any hope, remove the head and re-hone the valves. It needs a decoke for the overrunning anyway. So not an impossible task.
This past summer I had the radiator out to replace the slats. Fit one of Tom Langs SS thermostat housing, fit a new water pump and rebuild the dynamo and starter.
Also rerouted the heater piping in Stainless steel and fitted one of those Arnaut double hose takeoffs up front. My original heater rear head takeoff hose was 45 years old and did not looking too good. I guess I should have taken out the cam then, as it would have been easier. Lens roller cam set up looks like a good way to go and let's face it I only have 15 years of good driving left anyway So it should last me that long. Even without the paint job.
Thanks for the motivation..... later
Rod
Rod Jones

This thread was discussed between 14/01/2019 and 15/01/2019

MG TD TF 1500 index

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