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NZ_monty
New Zealand
63 Posts |
 Posted - 10/10/2011 : 08:44:00
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Hi,
I'm just looking at buying a PA and understand it to have the original crank, can anyone tell me if this is a bad thing and if I should be factoring in the cost of changing this to something stronger?
I new to triple M cars, but hoping to learn fast! :)
Thanks
Daniel |
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Mike Allison
United Kingdom
196 Posts |
Posted - 10/10/2011 : 09:00:59
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Hi Daniel,
The original crank in the P-type WAS a very sturdy piece of engineering, and will last a long time. However, over the years these have been subjected to a lot of hard use (the facility to reach 5500rpm plus is a necessity with such a small engine to attain any worthwhile power) and also may have had the journals re-ground from time to time. Also the original connecting rods will have been subjected to a lot of use.
When the engine was designed a life of perhaps 50000 miles was envisaged, which at the time was a LONG way, and the car was designed to last five=to=ten years. We are now eighty years after the event, so the car will possibly need attention.
If the crank is more than 0.040" down on pin size it must be considered suspect. I stopped work (retired) about ten years ago, and in the previous ten years had only found one crank which was acceptable. In the same time frame I found that I was rejecting one in four connecting rods for various defects.
A new crank and rods set was considered then a worthwhile expenditure, since failure of a rod would almost certainly make a hole in the crankcase, and a very large hole in your wallet.
So to answer your question, if you need a rebuild of the car, then replace the crank and rods, without question. If you are not under-taking a rebuild, then consider an engine rebuild!
The whole Triple-M range of cars was a great one, providing cheap sporting motoring, with a wonderfully lively engine to help things along, but they are no Bentley or Bugatti... but, then, those cars cost ten times the price of the MG! Personally I think MG's provide more fun pro-rata than any of the exotics, which is the pay-back.
Welcome to the fold, and experience some of the fun I have had in motoring over the past fifty-plus years!
Yours,
Mike
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NZ_monty
New Zealand
63 Posts |
Posted - 10/10/2011 : 09:12:14
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Thanks Mike, for the very quick and useful information.
I'm lead to believe the engine was rebuit not to long ago so will try and find out more tomorrow when I get the chance to go over the paper work and view the car! (so far I've only seen photos.)
I'm rather excited as I've wanted a triple M car for most of my life!
Cheers,
Daniel
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