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MG MGA - Crankshaft Compatibility

if my crank is damaged beyond repair in my 1500 can I have the machine shop switch it out with a 1600 with new re-ground beaarings? Will the 1500 piston rods fit the 1600 crank?
WMR Bill

Yes and Yes
dominic clancy

Sorry to be a pest, but the machine shop came back with bad news that my 1800 head is bad as well as the cost to redo the 1800 block. He did say the crank for the 1800 is in good shape, Can this be used in the 1500?
WMR Bill

No, crankshaft journal is a different size.

1500/1600 - 2.00 inches
1800 3 main - 2.162/2.1270 inches

Check with British Miles in Morrisville PA

He should have either although a rebuildable 1500/1600 core will be cheaper than an 1800 3 main.

Gioid luck.
Bill Haglan

Well I elected to utilize my 1600 crank and also replace the damaged rod with the one from the 1600. It is now clear that the ROD BEARING heated up and spun. The tab was clearly broken off and the bearing burnt. I am hoping this occured from just being worn an not an obstruction. My questin is, as a result of the failure a lot of bits of metal ended up in the bottom of the pan. Since I am not rebuilding and mearly changing out all the bearings and the newly polished 1600 cam, is there anything I need to watch for or do in terms of cleaning? Should I be concerned with the oil ports being obstructed?

WMR Bill

The major concern is that you get all the oil passages are checked clean. You also want to check the oil passages in the crankshaft, as this may be the reason that your bearing spun. If you can, before you put the crankshaft in, pressurize your oil system from the filter out to see whether you have any blocked passages in the engine.
mike parker

The Crankshaft will be clean because the machinest is hot tanking it before he polishes it. My big concern is the block. Should I attemmt to spray a carberator cleaner in the ports?
WMR Bill

I would, and you might also try to hook up to the oil pressure tap on the engine flush/blow the oil passages out.
mike parker

If you are changing one rod only you should check it for weight. Do a weight comparison with the other remaining rods, or at least one of them.

Mick Anderson

What would be the allowable tolerence between rods?
WMR Bill

Factory production con rods could vary as much as +/-1 ounce (28 gm), but they were selected in sets to be matched within 5 gm. The weight variation should be stamped on the part. See CSM MG/231 here:

Twin Cam con rods were heavier than push rod engine parts, but the same system applies, and the rods should be weight matched within 5 gm. If you put them on a postal scale and weigh both ends it is easy to grind a little off the non-contact surfaces to match the weights within 1 gm. I've been doing that for years for any engine that passes through my hands, just because it is so simple to do.
Barney Gaylord

This thread was discussed between 16/07/2008 and 21/07/2008

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.