Hints and Tips - Rev Counters

From: David Cochrane
Sent: 06 October 1999
To: british-cars-pre-war
Subject: Rev counter

Dear All,

JH's warning concerning speedos and other complicated components has prompted me to share an idea I've had for a while. I would like to fit a rev counter to my Austin Seven Special, but the original items have several problems, such as being incredibly rare, costing a small fortune and being complicated to drive. However the Smiths speedometers are comparatively common, so I thought that it should be possible to fit the guts of a modern electronic rev counter inside an original case. Diesel car rev counters go up to 6000 which is about right, and are available from my local car breakers yard for 10 quid (which includes the whole instrument binnacle). To save re-inventing the wheel, I wondered if any of you erudite lot had ever tackled this idea before?

Any comments would be gratefully received. In particular, how the modern rev counter derives its timing pulses from a diesel engine (electric ignition being noticeably absent). Also I will probably need to re-print the dial face; (in fact the speedo will have to be re-done as well) - does anyone know of someone doing these, or has got a computer to do it? It should be possible with relatively cheap and widespread scanners and good colour printers to produce facsimiles of white-faced Smiths instrument dials.

Regards,

David Cochrane

Rugby, England


From: Andy
Sent: 06 October 1999
To: british-cars-pre-war; David Cochrane
Subject: RE: Rev counter

Speedy cables of Islington, London N1. do this kind of work but may be expensive. See my parts page

--
Andy

Andy's Austin Seven Page


From: Bishop Peter
Sent: 06 October 1999
To: 'british-cars-pre-war'
Subject: FW: Rev counter

David I have done something very similar. The AH Sprite I used to have originally had a mechanically driven rev counter. I fitted a later electronic one into the original mechanical housing. This was a petrol one though and used an inductive loop to detect ignition pulses. I reused the original face and recalibrated the electronics to give the right reading.

Re timing pulses from a diesel engine, these must still have a 1/2 crankshaft speed pulse train generated in the management unit to drive the injectors? I have had the engine management unit from my Porsche in bits and that uses a single pulse generator to derive a clock source for both ignition and injectors, with a take of via an integrator to drive the rev counter. So I guess it would be possible to knock something up to detect ignition pulses from a coil system and generate the pulses to drive the rev counter.

I know someone who uses a computer /printer to print direct onto the surface of CDs - not sure if it could be adapted for Speedo faces but I could ask

Pete Bishop
Swindon
UK


From: David Cochrane
Sent: 06 October 1999
To: Bishop Peter
cc: british-cars-pre-war
Subject: RE: Rev counter

Pete,

Many thanks for the reply. I thought that I could take pulses from the ignition switch, which is connected to the magneto contact breaker. Unfortunately your car has a coil engine, otherwise I was wondering whether you could look at the pulses with a 'scope.... !

> Re timing pulses from a diesel engine, these must still have a 1/2
> crankshaft speed pulse train generated in the management unit to drive the
> injectors?

Could be - I find these moderns hopelessly complicated! I don't know whether these 5 - 10 year old diesels have engine management units or not. I must ask my local Peugeot garage.

> I have had the engine management unit from my Porsche in bits
> which uses a single pulse generator to derive a clock source for
> both ignition and injectors, with a take off via an integrator to
> drive the rev counter. So I guess it would be possible to knock
> something up to detect ignition pulses from a coil system and
> generate the pulses to drive the rev counter.

I think I will probably end up connecting it up and seeing what happens. At 10 quid a shot, it isn't the end of the world if I break one.

> I know someone who uses a computer /printer to print direct onto the surface
> of CDs - not sure if it could be adapted for Speedo faces but I could ask

Thanks, but I think all one needs to do is to print onto the special photograph-quality paper you can get for colour printers. and then stick that onto the old dial. It would also cover up the holes for the mileometer.

David C.


From: David Cochrane
Sent: 06 October 1999
To: David Laver
cc: british-cars-pre-war
Subject: Re: Rev counter

David,
> I've got a book on motorbike restoration which advises scanning and
> printing replica dials. The one tip that comes to mind is to print several
> at the time and keep the spares somewhere dark. If its only printed it is
> going to fade. I'll have a look this evening and see if there were any
> other tips. Maybe an art supply shop knows how to fix the ink?

I thought that the modern photograh-quality paper they use for colour printers may be OK. But a good idea to print spares.

George Filbey sounds expensive!, but I had a good chat with Tim who I think has solved the problem I'm going to have with the speedo. This is because I want an 80 mph one (rather rare) and I am using 19" wheels and a 5.25:1 cwp. Tim suggested using the early Chummy technique of taking the speedo drive off the propshaft, so I can fiddle with the pulley sizes until I get the correct ratio for my set-up. All this is rather in the future at the moment!

David C.


From: Stuart Ulph
Sent: 06 October 1999
To: David Cochrane
cc: british-cars-pre-war
Subject: Re: Rev counter

David Cochrane writes
> It should be possible with relatively cheap and
>widespread scanners and good colour printers to produce
>facsimiles of white-faced Smiths instrument dials.

I agree. For a non-computer method of doing this, see "The Vintage Motorcyclist's Workshop" by "Radco", pub. Haynes.

Regards, Stuart

P.S. It occurs to me that I have not given the list my credentials, so: 1933 Austin 7 4-seat tourer + a pair of ex-"Bill" Williams blown Ulster based A7 specials

--
Stuart Ulph


From: David Laver
Sent: 06 October 1999
To: Stuart Ulph
cc: David Cochrane; british-cars-pre-war
Subject: Re: Rev counter

> I agree. For a non-computer method of doing this, see "The Vintage
> Motorcyclist's Workshop" by "Radco", pub. Haynes.

That's the book - a great read even if you are not going to try wheel building or coach painting.


> P.S. It occurs to me that I have not given the list my credentials, so:
> 1933 Austin 7 4-seat tourer + a pair of ex-"Bill" Williams blown Ulster
> based A7 specials

Tell us all more on the specials !!

David


From: Mike Harris
Sent: 06 October 1999
To: British Cars Pre War
Subject: Dials

I have a Smiths PA speedo dial that I have scanned in and touched up. If anyone wants a copy e-mail me and I will send it as a file attachment.

Mike Harris


From: Barry Lovelock
Sent: 06 October 1999
To: Bishop Peter
cc: 'british-cars-pre-war'
Subject: Re: FW: Rev counter

I used a computer and 3M label making 'papers' for my speedo and tacho faces. However the computer was used to generate a completely fictitious dial (for calibration purposes), using Corel Draw. The 'paper' is actually a thin metal sheet, with a photographically processed, black coating. This gives a black face with aluminium figures. There is also a plastic version so one can get the traditional white on black look. If using most inkjet processes bear in mind the ink is usually water-based and will have to be lacquered to prevent running with moisture. Also my early prints have faded quite quickly, in about a year in fact. This could be considered a useful aging process for old cars though!

To produce the number plates for my Ulster - it had it's Australian plates when I got it, I scanned in a genuine 1930 plate, with similar letters and numbers and correct font. By converting the 3 into an 8 etc., I then printed the numbers on my HP890C on both plastic-coated paper and pure plastic paper stock to experiment and used both, one front - one rear. I sprayed the plates with a thick coat of clear lacquer, then very carefully dropped the scalpel-cut numbers on to the still wet surface. After pushing them down I re-lacquered the whole thing and left to dry. 18 months on the rear plastic one is still pristine, though it did peel slightly in one place. The front plastic coated paper one has aged really well, especially with the oil stains. The other car I painted the plates by hand.

Barry Lovelock.


From: Stuart Ulph
Sent: 07 October 1999
To: David Laver
cc: David Cochrane; british-cars-pre-war
Subject: Re: Rev counter

David Laver writes
> a pair of ex-"Bill" Williams blown Ulster
>> based A7 specials
>
>Tell us all more on the specials !!
>
>David

Flattered you should ask, David. I'll try to be concise. If you have a copy of Williams' book "Austin Seven Specials" - currently available cheap from Mill House Books, I notice - you can see a photo of one of the cars. It is the car W. built for J. Peter Almack. Quite pretty, I think, with pointed tail and inclined rad. Passed through the hands of Ken Jarvis pre war. He had some limited competition success with it. Has had various blown engines in its time, currently using a 10 - stud crankcase + replica Cozette mounted in front of the engine. Chassis is conventional Ulsteresque layout, only oddity the front axle which is 4 inches wider than normal. Williams rather grandly termed this the "Auto Conversions Front Axle", but it just involved a hacksaw and a welding kit. Almack fitted the car with rather exotic "Aerolite" 15 inch alloy wheels, made pre war by the Bramber eng. co. The other car is a sister car to Williams' personal sprint car. W's car was registered JO 66 and is pictured in his book. My car is virtually identical in appearance and was, I believe, the second one built. Like a slightly fatter version of the Almack car (the cockpit is 3 or 4 inches wider), routine Ulster layout chassiswise if you except the hydraulic brakes and Alfin drums. Little wheels, which I usually don't like, but having known the car on them for 35 years they look right to me now! 10 - stud engine, Grasshopper block, Centric blower in front. My Dad raced both of these cars on and off in VSCC events for 20 years or so, 1965 on. I don't consider either car to be particularly innovative technically but I do think they are quite pretty. Pity the nose sticks out ahead of the front wheels, but it does put the blower into a handy spot. Should have the Almack car on the road soon, I hope. Apologies for the length of this (heavily edited!) post.

Regards, Stuart.

--

Stuart Ulph


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