Bentall Exhibition

I spent a nice day sloshing mid-Brunswick Green around my stripped Petter M, fitting bigger wheels to my Amanco trolley (5" wheels looked ridiculous)

*AND* going to a local rally.

Living, as I do, within spitting distance of the original Bentall factory (although I doubt I could spit 3 miles these days) I've been to visit the local Agricultural Museum and the Museum of Power which have been celebrating the bicentennial of Bentall's. Both had exhibitions of ploughs - including the Goldhanger plough which is both the item that started the Bentall empire in the late 1700's and the village in which I live - mills, chaff cutters etc. but the Museum of Power had a fair selection of Bentall engines from around the country and one of two known remaining Bentall cars (the other currently resides in Australia). Although the ploughs were produced in the late 1700's, the Bentall factory was not established until

1805, hence the bicentennial.

Although I've seen quite a few Pioneers around the local rallys I'd never seen any of the hit and miss verticals - several of which were at the rally today.

Pictures at

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Regards

Mark

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mark.howard10
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Interesting set of pictures, Mark, thanks.

Love that car!

You said you were painting the Petter M. Did you fix the problem?

Regards,

Reply to
Arthur G

Hi Arthur,

Yes, the car is something special. It is alleged by some of the locals who maintain that they are 'in the know' that the car has square pistons. I really don't believe this but these chaps are adamant! I couldn't find anyone to genuinely confirm or otherwise (all I got was the inevitable strange looks as if I'd crawled from under a stone). Strangely, the four cylinders are bolted to a fabricated crankcase and they are distinctly square or diamond shaped! I still don't believe it though. I'm sure that this is folklore, the product of too many Abbot ales in the 'Maltsters' (the Bentall factory's local boozer).

No, I haven't fixed the Petter problem. I took the head off to check the piston (crown height, cracks etc.) and found nothing. The piston top is perfectly aligned with the bottom of the ports when at BDC and protrudes above the bore, into the head at TDC. So a duff piston doesn't seem to be the problem. I removed the cylinder because there was water weeping through the paint from some frost damage. I excavated the hairline crack and re-welded it - hence the need for new paint.

I also checked the ball-valve in the fuel nozzle which seemed to seal well under compressed air. I also checked the diaphragm for leaks to no avail. Oh, I also checked the exhaust pot and was disappointed find that it didn't require the application of a propane torch! (the neighbours were so looking forward to that as well :) ).

So far, I'm having to pin my hopes on either the weak spark (which I will prove with a coil and battery whilst I'm waiting for the mag. rewind) or some anomaly with the fuel nozzle which seems good at flooding the cylinder but maybe is not good at vapourising. There was one other thing that struck me as odd. The piston rings were all aligned with their gaps facing the inlet port (although there still seemed to be a good sudden release of crankcase pressure as the piston exposed the port). I have yet to check the gaps but they look a little wide - I forget the rule of thumb for calculating the ideal gap. perhaps one of the chaps can re-educate me.

Other than that I'm stuffed!

Mark

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Reply to
mark.howard10

Aaaah Has some cretin removed the screwed-in pegs that should keep the ring-gaps away from the ports ???? The atomiser only atomises rather than vaporises and if it floods I suspect the drain holes in the brass tube in the carb are blocked. The fuel level should be typically about 1/8" down from the top of the brass tube and NOT level with its top. ...and sometimes in the smoking rooms midst clouds of ers and ums, obliquely and by inference illumination comes (with apologies to Kipling...) ttfn Roland

Reply to
Roland Craven

Ah!!!

There is a distinct chance that you may have cracked the conundrum Roland!

I was standing there twiddling the rings around the piston and wondering why there was nothing stopping the ring gaps aligning themselves with the ports. I checked the ring grooves and there are no pegs or peg-holes! I, stupidly, made the assumption that the lack of pins or pin-holes was a 'design feature'!

The bore is only 1.5 (ish) thou' oversize so again I made the assumption that the piston had not been changed (or at least, not for an oversized item after a rebore).

It's a bit difficult to understand why the piston was changed when the bore wear is minimal but that is possibly a question that will never be answered. I suppose, but doubt, that the engine has never run properly (or at least was a PITA to start) which might account for the lack of wear throughout.

Anyway, the weekend should see a few pin holes created in the ring grooves - do you happen to know if they were originally a press fit or threaded? I would prefer to thread them as the piston expansion at running temperatures might make it a bit tricky to reliably press fit (I haven't done the calcs).

Thanks

Mark

Reply to
mark.howard10

See above :-)

Reply to
Roland Craven

Ah I see! The braincell escaped again :)

Thanks

Mark

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