Austin Healey 3000 Mk3 Rev Counter Woes
Jane Pilbeam
I have noticed that when travelling at 70mph in top-overdrive my rev counter
is at 5000rpm.
Is this normal? I only just bought the car and read that it should reach a
top speed of 115mph.
I can't see how that can be possible because the counter was almost in the
red at 70mph!
If anyone can help I'd be most grateful.
Dave Baker
>From: "Jane Pilbeam" janep...@btopenworld.com
>Date: 16/10/02 22:33 GMT Daylight Time
>Message-id: <aokluv$kvu$1...@venus.btinternet.com>
Hmmm - educated guess here - how about it has a 4 cylinder engine revcounter in
it for some reason which therefore thinks the 6 pot is revving 50% faster than
it really is? Cock up by a previous owner maybe.
That would put you at a true 3333 rpm or 21 mph/1000 which sounds a bit more
like it.
Dave Baker
Puma Race Engines (www.pumaracing.co.uk)
Dave Plowman
Dave Baker <pumar...@aol.comma> wrote:
> Hmmm - educated guess here - how about it has a 4 cylinder engine
> revcounter in it for some reason which therefore thinks the 6 pot is
> revving 50% faster than it really is? Cock up by a previous owner maybe.
> That would put you at a true 3333 rpm or 21 mph/1000 which sounds a bit
> more like it.
Clever theory. IIRC, if it's an electronic Smith's type, they're often
marked 4 or 6 cylinder, negative or positive earth etc on the face.
--
*Do infants enjoy infancy as much as adults enjoy adultery?
Dave Plowman dave....@argonet.co.uk London SW 12
RIP Acorn
Jon Tilson
"Dave Baker" <pumar...@aol.comma> wrote in message
news:20021016185156...@mb-fc.aol.com...
>
> Hmmm - educated guess here - how about it has a 4 cylinder engine
revcounter in
> it for some reason which therefore thinks the 6 pot is revving 50% faster
than
> it really is? Cock up by a previous owner maybe.
>
> That would put you at a true 3333 rpm or 21 mph/1000 which sounds a bit
more
> like it.
>
MGB's of similar vintage had cable driven ones....
My Dolly speedo reads far too fast cos of a broken spoing inside....but the
needle flops about rather...
Is the needle steady? WHat does it say on the small print of the instrument
face?
Jonners
AWM
"Jane Pilbeam" <janep...@btopenworld.com> wrote in message
news:aokluv$kvu$1...@venus.btinternet.com...
Normally I would expect it to be a mechanical tacho but it sounds like its
an electronic tacho look at the bottom of the dial -- it should say 6
cylinder if says 4 its the wrong one. Also check the rear of the instrumrnt
to see if it is a switchable type
Roger Chapman
from "Jane Pilbeam" <janep...@btopenworld.com> contains these words:
> Hi,
Not much of a help but something is well out of kilter. 115mph sounds
reasonable for a 3000 but not at over 8000 revs. I don't think it is a
high reving engine (the 100/4 certainly wasn't) so at 70 it should
surely be burbling along at somewhere in the region of 3000 in O/D top.
What does it sound like?
--
Roger
Dave Plowman
Jon Tilson <j...@blueyonder.co.uk> wrote:
> Nice theory Dave but would a big healy have an electronic tacho?...
> MGB's of similar vintage had cable driven ones....
The MGB changed to electronic with the 5 bearing engine, although I'm not
quite sure when that was. Mid '60s? So I'd guess the Healey changed at
about the same time?
The other possibility would be the wrong ratio right angle gear box - if
it has one. ;-)
--
*Why is it that to stop Windows 95, you have to click on "Start"?
Classic-Car-World Ltd
counter rebuilt by JDO instruments see www.jdo1.com. It would appear that
with the age of the instruments the internal components (Capacitors etc)
deteriorate and hence go out of calibration.
Hope this helps
Tom
--
Tom McCay
Classic-Car-World Ltd
Tel: 01522 888178
Fax: 0870 7059115
E-mail: enqu...@classic-car-world.co.uk
URL: www.classic-car-world.co.uk
"Jane Pilbeam" <janep...@btopenworld.com> wrote in message
news:aokluv$kvu$1...@venus.btinternet.com...
AWM
"Roger Chapman" <r.ch...@zetnet.co.uk> wrote in message
news:200210170...@zetnet.co.uk...
> The message <aokluv$kvu$1...@venus.btinternet.com>
>
> Not much of a help but something is well out of kilter. 115mph sounds
> reasonable for a 3000 but not at over 8000 revs. I don't think it is a
> high reving engine (the 100/4 certainly wasn't) so at 70 it should
> surely be burbling along at somewhere in the region of 3000 in O/D top.
> What does it sound like?
>
> --
> Roger
Doing the maths it looks like 4 cylinder rev counter has been fitted as
rpm the reading is about 1.5 times what would be expected.
The pro way of check a rev counter is to attach an oscilloscope to the
ignition -- quite quick and easy if you have the gear.
Incidentally a lot of road test top speed figures for cars with overdrive
were recorded in lower gears, 4th or overdrive 3rd.
Dave Plowman
AWM <not...@nowhere.freeserve.co.uk> wrote:
> Doing the maths it looks like 4 cylinder rev counter has been fitted as
> rpm the reading is about 1.5 times what would be expected.
> The pro way of check a rev counter is to attach an oscilloscope to the
> ignition -- quite quick and easy if you have the gear.
I'd have thought a DVM with a rev counter mode a cheaper option?
--
*In "Casablanca", Humphrey Bogart never said "Play it again, Sam" *
Op's
Dave Plowman wrote:
> In article <5Gnr9.28201$jR.1...@news-binary.blueyonder.co.uk>,
> Jon Tilson <j...@blueyonder.co.uk> wrote:
> > Nice theory Dave but would a big healy have an electronic tacho?...
> > MGB's of similar vintage had cable driven ones....
>
> The MGB changed to electronic with the 5 bearing engine, although I'm not
> quite sure when that was. Mid '60s? So I'd guess the Healey changed at
> about the same time?
>
Right 5 in 65
rm
Dave Plowman
Op's <mar...@wollongong.apana.org.au> wrote:
> > The MGB changed to electronic with the 5 bearing engine, although I'm
> > not quite sure when that was. Mid '60s? So I'd guess the Healey
> > changed at about the same time?
> >
> Right 5 in 65
Kewl. I'll not forget that now. ;-)
--
*Warning: Dates in Calendar are closer than they appear.
Geoff Mackenzie
"Classic-Car-World Ltd" <enqu...@classic-car-world.co.uk> wrote in message
news:2hvr9.506$005....@newsfep3-gui.server.ntli.net...
> Jane, I have the same problem on my 3000. This winter I am having the rev
> counter rebuilt by JDO instruments see www.jdo1.com. It would appear that
> with the age of the instruments the internal components (Capacitors etc)
> deteriorate and hence go out of calibration.
>
> Hope this helps
>
as is the odometer. It was when I bought it in 1974; following the full
rebuild recently over two years it still is. The axle ratio is correct,
the tyres are correct, but still the speedo and odometer are way off. My
local friendly restorer in whom I have great confidence has advised me that
it's not worth having the dial recalibrated by an "expert" as in his
experience you end up with a bill for £150 and no better result. Hope you
find a solution, and if you do please let me know!
Geoff MacK
Dave Baker
>From: "Geoff Mackenzie" geoff_m...@acsysindia.com
>Date: 17/10/02 22:27 GMT Daylight Time
>Message-id: <aona07$2vp$1...@newsg4.svr.pol.co.uk>
The drive gear inside the gearbox might be the wrong one. Or there may be one
with a different number of teeth that will correct the problem, if it lies
inside the speedo, more cheaply than recalibrating it.
A pinion with 15% fewer teeth would drive the speedo cable 15% faster in case
you're not sure which way round it all works.
Dave Plowman
Geoff Mackenzie <geoff_m...@acsysindia.com> wrote:
> Can only ask for similar help - the speedo on my 1966 E is about 15%
> slow, as is the odometer. It was when I bought it in 1974; following
> the full rebuild recently over two years it still is. The axle ratio
> is correct, the tyres are correct, but still the speedo and odometer are
> way off. My local friendly restorer in whom I have great confidence has
> advised me that it's not worth having the dial recalibrated by an
> "expert" as in his experience you end up with a bill for £150 and no
> better result. Hope you find a solution, and if you do please let me
> know!
If it were only the speedo, then it would be a relatively simple matter to
re-calibrate as IIRC it's an eddy current type. But if the mileometer is
out by the same amount it means the input to the instrument is wrong -
assuming the actual head is the correct one. This could be either
incorrect gears fitted to the gearbox, or one of the (two?) right angle
drives being of the incorrect ratio. My guess would be the gearbox being
incorrect after a rebuild. I've had exactly this on a Rover SD1 where
there is a choice of axle ratios over the models, but the same basic
gearbox. After a model is 'dead' there is a tendency for reconditioners
only to supply the strongest or best version of the box even for the less
powerful models, but can easily forget that speedo drive ratios are
different for those.
Have you investigated what right angle drives are available? It might just
be possible to fit the 'wrong' one to correct a different fault.
--
*Husband and cat lost -- reward for cat
AWM
"Dave Plowman" <dave....@argonet.co.uk> wrote in message
news:4b86d43cb1...@argonet.co.uk...
> In article <aom1i9$ng0$1...@helle.btinternet.com>,
> AWM <not...@nowhere.freeserve.co.uk> wrote:
> > Doing the maths it looks like 4 cylinder rev counter has been fitted
as
> > rpm the reading is about 1.5 times what would be expected.
> > ignition -- quite quick and easy if you have the gear.
>
> I'd have thought a DVM with a rev counter mode a cheaper option?
>
> --
> *In "Casablanca", Humphrey Bogart never said "Play it again, Sam" *
>
> Dave Plowman dave....@argonet.co.uk London SW 12
> RIP Acorn
Most serious workshops have one these days more or less essential for
working cars bult in the last 10 years and not as expensive as you might
think if you use one the plugs into a PC printer port. I use a bargain
basment Pico ADC40 cost less than 70 quid, only a single output and about
20k samples per second but they also do much faster twin input scopes in the
200 to 300 quid range. The supplied PICO Scope software is really first
class-- the web site is worth a visit and the demo software is worth
downloading http://www.picotech.com/index.html
Dave Plowman
AWM <not...@nowhere.freeserve.co.uk> wrote:
> > I'd have thought a DVM with a rev counter mode a cheaper option?
> Most serious workshops have one these days more or less essential for
> working cars bult in the last 10 years and not as expensive as you might
> think if you use one the plugs into a PC printer port. I use a bargain
> basment Pico ADC40 cost less than 70 quid, only a single output and
> about 20k samples per second but they also do much faster twin input
> scopes in the 200 to 300 quid range. The supplied PICO Scope software
> is really first class-- the web site is worth a visit and the demo
> software is worth downloading http://www.picotech.com/index.html
No thanks - I've got a lovely Tektronicx 465B which is probably *the*
classic scope. ;-) But I've never felt the need to use it on any car - yet.
Of course, if it was part of a fully equipped garage workshop, yes, but I
think one is overkill for an amateur, and well down the list after a
decent DVM and dwell meter etc.
--
*The older you get, the better you realize you were.
Geoff Mackenzie
> --
> *The older you get, the better you realize you were.
>
> Dave Plowman dave....@argonet.co.uk London SW 12
> RIP Acorn
Alternatively, for ex-racers, "the older I get the faster I was".
Geoff Mackenzie
"Dave Baker" <pumar...@aol.comma> wrote in message
Thanks, Dave, but I've checked the drive gear inside the speedo and it's
correct. In fact I've checked every bloody thing from the tailpipe to the
front bumper and it's still under reading! I rely on the rev counter to
keep me legal.
Geoff MacK
Geoff Mackenzie
the gearbox - yes, was rebuilt, but the speedo lag is the same as it was
before the rebuild. Agree with your theory that since the mileometer is out
by the same amount it must be the input. But how? Why? Oh well, I've lived
with it for umpteen years now - would be nice to get it right, though.
Geoff MacK
Dave Plowman
Well, the speedo drive gear in the box wouldn't normally be changed as a
matter of course during a gearbox overhaul. So I'd guess they just put it
back as found - unless you'd asked for it to be investigated. Is it
possible the gearbox was worked on before you got the car?
But have you checked up on what right angle boxes are available? I know
they're not all the same ratio.
--
*Too many clicks spoil the browse *
R. N. Robinson
"Geoff Mackenzie" <geoff_m...@acsysindia.com> wrote in message
news:aoq1s8$nsv$1...@news5.svr.pol.co.uk...
>
> >
> Thanks, Dave, have checked the right-angle drive and it's the right one.
Re
> the gearbox - yes, was rebuilt, but the speedo lag is the same as it was
> before the rebuild. Agree with your theory that since the mileometer is
out
> by the same amount it must be the input. But how? Why? Oh well, I've
lived
> with it for umpteen years now - would be nice to get it right, though.
>
Was there ever a choice of rear axle ratios for the E-type? If so the
speedo drive gears on the gearbox output would also be different, and maybe
somehow or other your car has acquired a pair that don't match the axle
ratio.
Ron Robinson
Dave Plowman
R. N. Robinson <ron...@grumiousbandersnatch.freeserve.co.uk> wrote:
> Was there ever a choice of rear axle ratios for the E-type? If so the
> speedo drive gears on the gearbox output would also be different, and
> maybe somehow or other your car has acquired a pair that don't match the
> axle ratio.
I'm pretty certain the gearbox wasn't unique to the E-Type even if they
did have alternative ratios, but I'd guess the saloons that used it would
have been different.
--
*If one synchronized swimmer drowns, do the rest have to drown too?
Geoff Mackenzie
"R. N. Robinson" <ron...@grumiousbandersnatch.freeserve.co.uk> wrote in
message news:aosbnp$2f9$2...@newsg4.svr.pol.co.uk...
Yes, there were three different rear axle ratios for the E depending on the
market. And in my case, everything is as original and matches. I know that
Jaguar manufacturing was pretty awful in the sixties, but as far as I can
work out it should all be OK. Oh, bugger!
Geoff MacK
Geoff Mackenzie
Well - yes - but my gearbox has the same number as it had in the original
docs. So I don't think it was a different box fitted thereafter.
Re synchronized swimming - a whole US aerobatic team went in a few years ago
as the members followed the leader.
Geoff MacK
R. N. Robinson
> In article <aosbnp$2f9$2...@newsg4.svr.pol.co.uk>,
> R. N. Robinson <ron...@grumiousbandersnatch.freeserve.co.uk> wrote:
> > Was there ever a choice of rear axle ratios for the E-type? If so the
> > speedo drive gears on the gearbox output would also be different, and
> > maybe somehow or other your car has acquired a pair that don't match the
> > axle ratio.
>
> I'm pretty certain the gearbox wasn't unique to the E-Type even if they
> did have alternative ratios, but I'd guess the saloons that used it would
> have been different.
>
I'm sure you're right, Dave. A bit of work with a calculator and you could
probably identify what model the speedo drive gears came from. I ran into
something like this myself when fitted a later gearbox to my Lea-Francis.
It had an overdrive and came from an Armstrong Siddeley 234, which had
different gearing. In my case I got away with just a change of the gear on
the output shaft, the pinion running all right with it after a few minutes
in the lathe with lapping paste.
Ron Robinson
R. N. Robinson
>
> "Dave Plowman" <dave....@argonet.co.uk> wrote in message
> news:4b8808535d...@argonet.co.uk...
> > In article <aosbnp$2f9$2...@newsg4.svr.pol.co.uk>,
> > R. N. Robinson <ron...@grumiousbandersnatch.freeserve.co.uk> wrote:
> > > Was there ever a choice of rear axle ratios for the E-type? If so the
> > > speedo drive gears on the gearbox output would also be different, and
> > > maybe somehow or other your car has acquired a pair that don't match
the
> > > axle ratio.
> >
> > I'm pretty certain the gearbox wasn't unique to the E-Type even if they
> > did have alternative ratios, but I'd guess the saloons that used it
would
> > have been different.
> >
> > --
> > *If one synchronized swimmer drowns, do the rest have to drown too?
> >
> > Dave Plowman dave....@argonet.co.uk London SW 12
> > RIP Acorn
>
> Well - yes - but my gearbox has the same number as it had in the original
> docs. So I don't think it was a different box fitted thereafter.
The speedo drive gears aren't very far into the box - outside it really. Do
you know if it was ever rebuilt or anything before you got the car?
>
> Re synchronized swimming - a whole US aerobatic team went in a few years
ago
> as the members followed the leader.
Isn't that the definition of a good formation aerobatics team?
Ron Robinson
Geoff Mackenzie
"R. N. Robinson" <ron...@grumiousbandersnatch.freeserve.co.uk> wrote in
message news:ap1dpd$5c2$2...@newsg4.svr.pol.co.uk...
and the mileage then seemed about right for the condition - about 80k. If
the speedo had been replaced I would have expected it to show a much lower
mileage.
Re the aerobatics - sadly, you are quite right - you are expected to follow
the leader. But if he makes a mistake you do have a problem.
Geoff MacK (former member of TWWAT - The World's Worst Aerobatic Team).
R. N. Robinson
>
> >Snip
> Ron - as far as I know it was the original speedo. I bought the car in
1974
> and the mileage then seemed about right for the condition - about 80k. If
> the speedo had been replaced I would have expected it to show a much lower
> mileage.
>
had done some work on the gearbox before you got the car and mistakenly
popped the wrong drive gear onto the output shaft before putting the rear
cover on.
> Re the aerobatics - sadly, you are quite right - you are expected to
follow
> the leader. But if he makes a mistake you do have a problem.
>
> Geoff MacK (former member of TWWAT - The World's Worst Aerobatic Team).
>
Never mind - you're still with us :-)
Ron Robinson
Geoff Mackenzie
>
> "Geoff Mackenzie" <geoff_m...@acsysindia.com> wrote in message
> news:ap1r8m$no4$1...@newsg2.svr.pol.co.uk...
> >
> > >Snip
> > Ron - as far as I know it was the original speedo. I bought the car in
> 1974
> > and the mileage then seemed about right for the condition - about 80k.
If
> > the speedo had been replaced I would have expected it to show a much
lower
> > mileage.
> >
> It wasn't the speedo I was thinking of. I was wondering whether someone
> had done some work on the gearbox before you got the car and mistakenly
> popped the wrong drive gear onto the output shaft before putting the rear
> cover on.
Nope - checked that.
>
> > Re the aerobatics - sadly, you are quite right - you are expected to
> follow
> > the leader. But if he makes a mistake you do have a problem.
> >
> > Geoff MacK (former member of TWWAT - The World's Worst Aerobatic Team).
> >
> Never mind - you're still with us :-)
>
> Ron Robinson
>
Thanks! Wonder what happened to the other guys...?
Geoff MacK (our definition of a formation flight was when you all took off
from the same airfield and at least one landed back at the same airfield on
the same day).
Jane Pilbeam
very helpful.