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MG TD TF 1500 - Piston height / decked block; what to do

I think I'm in trouble with my pistons that stand proud of the engine block that was probably decked more than one's.

The old head gasket is about as thick, leaving almost no clearance, I don't think that's enough? See the pictures.

What is the best solution, apart from getting the pistons out again and having them turned down?

Willem van der Veer

and another picture

Willem van der Veer

Two head gaskets.

Either bite the bullet and turn them down (have seen that done on a local TF1500 engine), or better than two gaskets, have a thicker solid copper one made. George
George Butz

I also recommend a solid gasket - NOT 2 head gaskets. Gasket Works USA sells solid copper head gaskets; I believe Moss sells .032 solid gaskets for banana blocks. Look in the archives; I believe there is someone else who makes them.

Tom Lange
MGT Repair
t lange

I have used twin head gaskets without any problems. I fitted undamaged gaskets that had been used before and had therefore been compressed, and smeared both sides with a thin layer of grease - there were no leaks. However, going by the second photo, two gaskets may not be thick enough.

As Tom says, solid gasket or turn the pistons down.

My buddies building big blocks would go as tight as .040 squish. I believe a small bore such as these with less piston rock can go smaller. Mine is at about .038-.039 minimum. It's probably more as that was my guesswork on gasket compression worst case.
J E Carroll

From earlier correspondence with Gasket Works, they will cut you a gasket of almost any thickness, but a solid copper gasket is probably the most expedient way to solve the peoblem. Just tell them what you want.

There is however another solution, and that is to lower the wrist pin centre. That can be done by fitting the rod with a slug for a wrist pin, then drilling it off-centre by an amount equivalent to the piston height excess.

If you have an oil scraper ring below the the wrist pin, carefully check with the engine on the bench, that the scraper doesn't come below the cylinder wall, when the crank is rotated by hand.

This does NOT change the cylinder volume as the swept height remains the same.

Gord Clark
Rockburn, Qué.
Gordon Clark

Cost wise, go with a solid copper gasket! Double gaskets is asking for future problems. Get Gasket Works to make you one the proper thickness to allow the correct clearance from the top of the piston to the head. Too close, even though the pistons clear the head, allowance for some stretch has to be incorporated, especially if you are going to run it at high RPMs. I temporarily install a head using a piece of clay on top of the piston, rotate the engine slowly, pull the head and take a thickness reading from the clay. No guess work! But that's just me.
Other option, but more work and higher cost, depending on piston head thickness, have them cut down. PJ
Paul sr

I had that same problem when I bought a crank for my MG midget. Turned out that the vendor had sent me a stroker crank by mistake. Just something to check...
David Littlefield

Thanks for all the replies. I'm a bit in a hurry so will go the twin head gasket route and agree that's not a permanent solution. I guess Gasket Works won't be able to get it in Holland in a week.....

What kind of copper is used in these solid head gaskets? I'm thinking of buying a copper sheet of 2,5 mm / 0.1 inch thickness and saw out a head gasket. After modelling heating and tempering should make it soft enough?
Willem van der Veer

Hussey Copper in PA USA can custom make a copper gasket to your specs. They did mine and it was not that expensive.
Tom Maine

If you can find someone with a water jet machine they should be able to copy a standard gasket on sheet copper. That may be the quickest way rather than shipping from the US.
J E Carroll

Can anyone give me the original factory dimension, from the crank centre to the top of the block.
Wes Hayes
New Zealand.

The measurement from the sump gasket face to the top of the block, as best I can measure it, from an unmodified block, is 270mm. This is an easier dimension to measure.

Thinking outside the box - how about pocketing the head?

I do this for MGB supercharger engines to increase the chamber capacity - mount a 1" cylindrical stone in a router and remove metal to the required depth out to the gasket diameter.
Chris at Octarine Services

I've now ordered a 0.086 thick copper headgasket at Gasket Works ( the USA. I hope it arrives quickly.
Willem van der Veer

This thread was discussed between 09/06/2013 and 16/06/2013

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