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MG TD TF 1500 - Engine Rebuilding question

Hello everyone

I'm having and engine rebuild winter as I have two engines that I am going to rebuild in the next few months. One for my YT and another as a spare. Best way to store boxes of engine parts is to build an engine!

As the big end of the connecting rods is larger that the bores of the cylinders, what is the accepted method of installing the pistons.

I am leaning toward putting them in the cylinders without rings, and installing the rings with the piston pulled out the top of the engine and then using a ring compressor to put the piston back in the block.

Any other thoughts?

Thanks.

Joe
Joseph D Hine

Joe, that is how I installed them in my YT's XPAG engine. Best of luck with your winter project(s).

cheers Stuart
Stuart Duncan

That's what I did what I did when I replaced the pistons and rings with the engine still in the car. I did not install the fourth ring on the four ring pistons and the car does not smoke. That was in 2014.
Regards
Declan
Declan Burns

I compressed the rings and inserted the pistons from the bottom.
Regards, Tom
tm peterson

Either works. Much easier to install the rings on the bench. I recall the cylinders have a bevel at the lower end which would make insertion easier from the lower. Of course the crank must be out to do it that way. George
George Butz III

George,
I did not remove the crank when I replaced the pistons and rings. It is a very tight squeeze. I agree it would all be easier on the bench.
Regards
Declan
Declan Burns

If the bore is .060" or less it can be done with the crank in place.
If doing it with the crank in place it can not be done with a 3 piece oil ring IMO.
I strongly recommend Ceramic coating of the piston crowns and dry film coating of the skirts.
Len
Len Fanelli

I always try to do things as easily and reliably as possible. So I remove the crank, always.

i install the pistons on the rods, push them up through the bore and sticking out the top, and put the rings on there. I then compress the rings and push the pistons back down. I then install the crank, attach the rods, and am done. The bottom of the engine is not conducive to using a ring compressor, which is why I use the flay deck.

Tom Lange
MGT Repair
t lange

Thank you all for your replies. I think my first thought of up through the bore and then install rings as Tom and others have said.

Joe
Joseph D Hine

Through the bottom for me and if you think about it, it's the way they put them in when they were built originally.




L E D LaVerne

Yes, LaVerne, but the factory probably had a bespoke tapered installation sleeve, so a quick single push installed each piston and rings in one motion from the bottom.

Tom Lange
MGT Repair
t lange

For an XPAG:
If the bore is .060" or less it CAN be done with the crank in place as the factory chamfer will still be enough to compress the rings, without a ring compressor> the way the factory did it WITHOUT the crank in place.
Pistons larger than .060" may not get past the crankshaft. You can only do 1 piston at a time.
If doing it with the crank in place it can not be done with an (Aftermarket) 3 piece oil ring IMO.
However using this method is only recommended if you want to leave the engine in the car to remove & replace the pistons and rods as in re ringing the pistons.
When the engine has been bored so much that the chamfer will no longer be there or enough to compress the rings it is good practice to have the machine shop machine a new chamfer.
Len
Len Fanelli

This thread was discussed between 13/12/2023 and 21/12/2023

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