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Old 26th May 2017, 16:59
Scottie22 Scottie22 is offline
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Default 1300

Thanks for the input Mick, I do appeciate it, but I think that Oxford may well be able to hepl me with this one!

Thanks for that Degsy! (what is written below goes into more detail to try to
explain why I chose the 1300 and am sticking to it)

I did not know that the 1300 also only had a three bearing crank, but what I DID know, was that the Spitfire 1300 engine loved to rev highly, and was quite happy to do so, and, in fact was so good at this, that in 1965 at Le Mans, three 1300 engined Spitfires came 1st, 2nd and 3rd in class, and would have come 4th but the car crashed before it finished!
And they did all this by revving the little engines at 9000 revs for 24 hours at over 100 mph!!

This is because, whether those 1300 engines had the lighter crank or the the heavier crank, the cranks were made from EN40B steel. BLMC upon introducing the “1500” engine in 1968, increased the stroke and downgraded the crank steel to EN16U an inferior steel, because it was cheaper.
Knowing that the steel was inferior BLMC increased the size of the crank to compensate, but left the bearings the same size.
This had the result of slowing down the revving, wearing the bearings out faster, and mainly introducing the dreaded “crank-flexing” which often destroyed engines when the oil broke down.

So whilst the 1300 will rev quickly and live long doing so, the 1500 will not due to the longer stroke, heavier crank, and effectively smaller bearings.

By all accounts, ALL 1500 Triumph engines were referred to in the trade as the “floppy-crank” engine.

So, that is the reason I am still sticking to my plan for a 1300 motor.

I do not wish to insult anyone who likes the 1500 motor, and, by all accounts there are several ways to increase the longevity of these engines, and apparently some people do actually race 1500 triumphs successfully, but for me, the easier route is to just use a 1300 engine having been burned twice by the 1500.
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