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MG Midget and Sprite Technical - Could be much worse...

Thank goodness I took my own advice...

I have always said that if your engine goes sick while racing it is a much better idea to switch off than to keep going and hope it clears... I have seen many grenaded engines where people did just that.

At Mallory in October I was running third in class and hassling Andrew Actman for second (Mark Turner having disappeared up the road)on the second to last lap I came into the hairpin and felt my engine suddenly go rough - I accelerated out but the oil pressure was dropping and it just felt wrong - I switched off and coasted into the pits looking at the 'last lap' board as I did so.

I stripped my engine tonight - initially couldn't see anything wrong so was starting to think I'd thrown away a decent finish when I undid the No4 big end - I have attached a photo of what I found... I reckon another half lap and it would have exploded which would probably have trashed the entire motor - as it is I will get away I believe with a replacement crank - there doesn't even seem to have been much in the way of debris going through the engine - the centre main is unmarked as is the oil pump...


J A Bilsland

The reason for the crank failure? Fatigue pure and simple. This is an EN16T crank that has been subjected to high revs (8k plus) over many seasons... It is to be replaced with an EN40B crank...
J A Bilsland

James

Any chance you can bring it along so I can have a closer look?
Dave O'Neill 2

I cant belive you stole my pics

...same thing a over a year ago and the same type of crack, and same place luckly I did the samething...shut it down, only damage was the bearing shell

BTW..Im also using a EN40B crank and 521 rods


Good luck, Hope your build goes better then mine...

Prop




Prop

Yes, will do

James
J A Bilsland

Thanks Prop - don't worry - you're getting close now... :)
J A Bilsland

James

wow

just in time
bill sdgpm

Yeah, I was going to say... looks just like the failure that Prop had with his engine.

-:G:-
Gryf Ketcherside

Not another Prop saga!!!!!!

James only report back when you have the new engine started, we can not do with all that again, well I can't anyway!
Robert (Bob) Midget Turbo

Just heard from CDC, there is a pandemic Prop virus loose in the world!

FRM
FR Millmore

What happens when all the crankshafts for a-sreies engines have failed?
S.A. Jones

get new ones made from billet...
David (davidDOTsmithAT stonesDOTcom)

>>>>>>> get new ones made from billet... <<<<<<<<<

Or save a few dollars and buy a complete K-series then have it flown over 1st class overnight priority to the USA. LOL

Prop...it is made from ally ya know.
Prop

Well saved that man! I hav'nt seen one in such good nick for years, (apart from Prop's).
Did you make any changes just prior to failure, i.e. flywheel/clutch assy. that was not balanced with the shaft?
Sling the vibration damper as a precaution, unless, that is, it's a viscous one where you can have it tested out.
It's worth investigating cause of failure as it looks pretty clean and should still indicate starting point of stress raiser, (poor fillet radii, oil hole drilling etc).

Peter
PJ HOBSON

No changes to the engine since I built it in 1999 apart from season end rebuilds (bearings, oil pump, rings, valve springs, rod bolts, followers and the occasional cam change)

Crank damper is going in the bin. EN40B crank (which I have to collect from Mr O'Neill) will be balanced with the flywheel, clutch and new damper (going belt drive with a Cooper S damper).

I'll have a good look for the failure point but I can't blame the crank - its been in the engine since 99, done about 75 races including long distance events (hour long driver change, FISC Nordschliefe etc...) and before that did about 10000 miles in my road going midget with a 1293 full race engine in it - frankly I am amazed the thing lasted as well as it did considering its a standard (balanced only) EN16T crank on 10/10...
J A Bilsland

'What happens when all the crankshafts for a-sreies engines have failed?'

I wouldn't worry - we'll either be long dead, the oil will have run out or both...
J A Bilsland

'Not another Prop saga!!!!!!

James only report back when you have the new engine started, we can not do with all that again, well I can't anyway!'

Don't worry Bob... I don't do over complicated... My old boss Bill Richards learned his trade at Special Tuning, and I was taught by him... :o)
J A Bilsland

James do you have the block centre main bearing strapped?

I suppose you must have given all that history

... my next move for the 1293 in Lara

and oh yes

no more sagas... please

:)
bill sdgpm

Yes - A+ Maestro block with a steel centre main strap
James Bilsland

This thread was discussed between 03/12/2009 and 04/12/2009

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.