Query about gearing...

[Ivangardiner]

Hello Duncan,  you said you were wondering about the auto advance, and I see that Bob Culver also asks if it is working.  Have you actually checked it with a timing light?  It's a sure way of knowing whether the automatic advance is working properly.  If the auto advance is not working then obviously the timing will be way too far retarded at running speeds, even though at idle speed it may be correct.  On the Bantam I used to lift the floor covers, put a mark on the flywheel at the TDC and shine the strobe light on it while revving the engine.  If the mark does not move clockwise by about 20 degrees (not sure of the exact figure) then you may have found your problem.  Good luck

[Duncan Grimmond]

Well, thanks to all for their contributions. I've been busy on hold (approximately 15 hours this week) to BT who seem to be unable to make a telephone system that functions....

I don't have a rev counter fitted, I'll buy a cheapie off Ebay to try.
The distributor is not as good as I might expect and will fit the electronic Acuspark
The exhaust is a cherry-bomb on a shortish front pipe, (stops just aft of the front cross-member) very little back-pressure
I also considered the binding of (the hydraulic) brakes and checked all round
Without a wind tunnel I know nothing of the aerodynamics but recognise that this may well cause a problem

I went to start it yesterday and it did not want to play which is unusual as I've found Austins very easy to start. There seems to be a fuel starvation problem as it will tick over but kill itself as soon as the throttle is opened so I plan to leave the distributor alone until :
check the delivery from the electric pump, check the main jet on the Solex is clear of muck which may have fought its way through the inline filter.
check the float chamber is filling adequately
The air-screw seems to function effectively, I'm setting it 1 1/4 turns open from zero and it has worked satisfactorily at that for the last year
Unfortunately I cannot find a reference guide for the Solex on-line, the info seems to be regarding Reliant instruments with no illustrations or set-up guide. Does anyone out there have a link?
I do not know what K Rawson (?) did in 2011 when he rebuilt the engine/gearbox/diff other than the reputed Phoenix crank and HC head .

[Steve Jones]

I've sent you an email, Duncan.

Steve

[Nick Lettington]

Of course there are so many moving parts it is hard to pin down the problem. I recently replaced the diaphragm in my petrol pump, realised the valves weren't seating properly... replaced the pump and found a new top speed...

[Howard Wright]

Hi Duncan

Another report back regarding iPhone based rev counters.  This one the free “strobe light tachometer”.

This was very good.  I wanted to check the speed of my electric drill so that I could then attach it to the speedometer drive to know if it was recording correctly.  All you need is a surface perpendicular to the rotation (a sanding disc in my case) with a white dot or line on it.  Pointing the flashlight at the disc it strobes to the frequency shown on the screen.  Altering the frequency until the dot appears still gives you the revs/minute.

Turned out my 1500 rev/min drill only turned at 1100.

I’ve yet to try it on the engine and guess I would need a clear sight line to the flywheel (or cam pulley). Unfortunately not something you can use as you drive along☹️.

Cheers

Howard

[andrew34ruby]

Of course Andrew, forgive me for not knowing what I am talking about, I will leave the matter in your more than capable hands.

Ian, you could have just said I was wrong, which I probably was.

[Ian Williams]

I probably could Andrew, so my apologies, your response made it appeared you have already made up you mind that I was talking nonsense. Perhaps I am, but I usually try to only state facts and opinions when I have some experience which I believe may be helpful to a problem. You had already received some excellent advice around gearing and how to tune engines, but appeared fixated on the fact that you Ruby was out performing Duncan's special. That to me dictates that something is significantly wrong with Duncan's set up, which I felt quite was likely to be carburation and timing This was because as you now know the gearing difference between your cars is insignificant, and now that you understand weight and frontal area better you will I hope realise that even with the same bog std engine specification Duncan's car should quite happily out perform your Ruby. Sorry if I caused offence by being offended.

[andrew34ruby]

It seems I was wrong to ignore rolling resistance. I felt it would be insignificant compared to wind resistance, but probably not at speeds of 40 or 50.

Also, does a heavier car have more rolling resistance. It probably does, but how much more.

[Howard Wright]

Hi Andrew

I wonder if rolling resistance is directly related to friction (in the bearings)?  If so the resistance will be directly proportional to weight of car. It always confuses me when I’m told friction is a function of perpendicular force not area of friction material.  Theoretically 1” brake shoes should perform the same as 1 1/4” shoes. But that doesn’t seem to be the case in practice.

Cheers

Howard

[Nick Turley]

All in all it would appear that it is something wrong with the engine no question.
Clearly what is required is testing to diagnose the problem.
Must say given the none standard carburettor that would be my first port of call.
Duncan I suggest again to you that you try a carburettor off an engine which is currently running well.
Circumstantially sounds most likely to be the area of concern to me, happy to lend you one if needed.
It is sensible of course to only change one thing at a time.
The lack of performance sounds like a lot, it must be a simple problem.