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MG TD TF 1500 - MGTD compatible piston?

I am getting ready to start a restoration of an MGTD.
I have found some pistons and rods online that are stated to be from an MGTD. They have 4 rings so my understanding is that they are not original TD pistons. That is ok with me as long as they fit my needs. I only have photos to go by and not measurements at this time. Can these be identified by the photos? The pistons have .080 stamped on top(which is what I am looking for). It also has 68.49 stamped on top which, if my calculations are correct, would be accurate for a TD piston sized .080 over. There is a marking on top which I can't identify. It is a circle with an inverted "E" in the middle, R10 over it and 033 (could be D33)under it. Could this identify the origin of the piston?

The rods are cast with MOWOG 24006 +40 on them. Does any of this help identify the pistons and rods?

Thanks for any help you can give.
Jim Smith
JV Smith

Jim - you are risking a whole lot by approaching an engine rebuild like that; you cannot simply replace one used part with another from another source, and expect it to be satisfactory. An engine needs to be carefully measured after a full cleaning, to determine wear. For instance: your old pistons might be marked +.080, but the taper in your engine's +.080" bore (due to nothing more than normal wear) might be greater than acceptable, so you would have to have your engine over-bored to the next larger size, and new pistons and rings sourced. You really need to have the engine completely cleaned by a qualified machine shop, magnafluxed for cracks (along with the crank and rods), and measured, in order to obtain the correct parts.

Bores wear, pistons wear, rings wear, crank journals - both rod and main - wear, cam shafts and followers wear, and THEN all need to be measured and evaluated for usability and suitability. 4-ring pistons were, I believe, standard, the 4th ring being a ring down low in the piston (many people throw away that ring, as added weight). But that is also likely to be an old piston, since most current pistons are 3-ring.

As for rods, unless your engine has a real problem, it is normal to have a machine shop rebuild your rod - the main journals tend to get oval - rather than replace it. It is standard procedure to re-hone a rod back to standard; there is little reason to replace a rod, under normal circumstances.

We are happy to guide you through an engine rebuild, but doing a half-hearted job will inevitably result in an unsatisfactory engine job.

Tom Lange
MGT Repair
t lange

I second what Tom said.

Somewhere between reliably driveable safely and Concours should be your goal. Only you can decide where your resto/rebuild will fall on that scale for your purposes and enjoyment.

Regards, Tom
tm peterson

Yep
New piston and ring sets aren't that expensive really, and you'd need at least new rings anyway
Buying second hand engine parts is playing with danger--do it right first up then you don't have to do it again.
willy
William Revit

Jim In addition to the above comments I recommend line boring the main bearing bores in the block. The factory tolerance for main bearing clearance is .0008"-.003" for a new engine. Engines that were assembled with.003" main bearing clearance leaked lots of oil. When line boring the bearing bores to achieve .0008"-.001"clearance you will have almost no oil leaks past the rear main bearing & scroll. The process is the same as rebuilding the big end of the rods (resizing) milling a few thousandths of an inch off of the caps then honing back to round.Find a machine shop that do this and ask if they have the tooling to do the (small) main bearing bores of this engine.
As with Tom we also will help with any questions that you may have.
Len Fanelli
Abingdon Performance Ltd.


Len Fanelli

Just for reference:-
This was a piston taken out of my TD engine back in 1972 The bottom ring is an oil scraper ring I belive. Hollow with lots of holes. Theres a channel underneath it with two large openings on each side to alow return oil. Skirt is also split.
The top ring slot has the only solid ring. The two other ring slots hold several very thin rings, 3 and 5. They have their open ends spread around the piston.
Cant remember what I put in now but I do beleive they were new Hepolite +20's. Crank and bearings were Std.
Balldyne Enginerring of Sidcup in Kent did all the work and balancing. Top marking are FRONT and 14136.
Made a good ashtray - back in the day





Rod Jones

After my engine was cleaned and measured, i ordered modern pistons from Venolia Piston in CA and new modern rods from Crower Rod, also in CA about 1400 bucks. that was 20 years ago but they are still going strong in my car, now owned by my nephew. it was a good way to go.
TRM Maine

This thread was discussed between 10/04/2020 and 13/04/2020

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