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MG TD TF 1500 - TD Pistons

I am rebuilding a TD engine. It is the first TD motor I have worked on (I own a midget with an 'a' series motor). I think I have made a mistake. I have fitted the cam and crank. I have measured everything along the way with plastigage. The main bearing nuts were a bugger to line up with the holes, but plenty of swapping got them there in the end. I have read up on fitting the timing chain, mine had no marks, so I marked the links at 13 and 15. This is fitted along with the tensioner, whose bolts are lockwired. I have checked the new big ends and the ring gaps. The pistons are assembled and ready to fit - but you have guessed it - the rods do not fit down the bores! Probably elementary to you guys. Do have I have to dis-assemble, or is there another way?
Shawn

you are going to remove the crank. regards, tom
tom peterson

Shawn,

I've heard it is possible to get the rods in with the crank and the camshaft in place, but it is difficult. The procedure I've heard is it has to be done on the camshaft side of the engine and it's a bit tricky. The crank rotation, piston and rod all have to be manipulated in order to "sneak" the assembly in. You may have to install the gudgeon pinch bolt (little end) in place after the piston is past the crankshaft.

I think I would simply chalk it up to experience and undo the work, install the rods and pistons from the bottom and work from there. Incidentally, I installed my rings after I pushed the pistons up from the bottom, except for the lowest ring on my four ring set which I put in from the bottom. You can use a hose clamp to act as a ring compressor in the little space for the bottom ring. Watch the direction of the pinch bolt clamp. It has to be correct.

Finally, check out using hardened allen headed screws for the gudgeon pinch (little end) bolts. Get hardened ones, see my website, www.dbraun99.com for engine rebuild pictures.

warmly,
dave
Dave Braun

shawn, to expand a bit... after removing the rings from the pistons i think you may be able to snake the piston/rod assembly down past the crank. if you are able to do this you can put the rings on with the pistons sticking out the top of the block. or..i have never done this, but if the above does not work you may be able to remove the piston from the rod, snake the rod through the block and reinstall piston. not sure if you could get to the gudgeon bolt with the rod in the block. i would remove the crank before i did any of this. i have done a couple of xpag engines and i torque with locktite and do not even bother with the safety. my friend has a machine shop for 30+ years and does racing motors for several clubs in the area and does not safety. he says torque is the key and has never had one come undone. regards, tom
tom peterson

The piston/rod assembly can be installed with pinch bolt, with crank in place, left side of engine, rotating the crank, pinch bolt on right side. The bottom of the bore has a chamfer to compress the rings, this chamfer gets smaller with every over bore.
Len Fanelli

This thread was discussed on 13/03/2009

MG TD TF 1500 index

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