Subject: Re: [Healeys] fuel gauge calibration

From: Oudesluys <[email-masked]>
Date: Thu, 07 Nov 2013 11:53:41 +0100

Depending on the make/type of car these Smiths/Jaeger gauges can 
indicate a (nearly) full tank for a fairly long time and then drop to 
1/4 full rather quickly, the system is notoriously inaccurate. Just 
learn to live with it and fill up when it reads about 1/4 full to be on 
the safe side or check the odometer as a guide when to fill up. It is 
probably because of the way the lever arm in the sender is moving and 
certainly the shape of the fuel tank. This is different from in every 
car make and type and is the cause of a non-linear signal.
However if the gauge is really at fault find an identical Smiths on 
ebay.co.uk and transfer the Jaeger dial to it, taking great care not to 
bend the indicator hand. The Smiths gauge being way cheaper than the 
difficult to find Jaeger item. The gauges are absolutely identical but 
for the brand name.
Kees Oudesluijs
NL

john spaur schreef op 7-11-2013 7:27:
> There have been quite a few posts on this issue but none seem to 
> really solve the problem. When I first owned an Austin-Healey it was 6 
> years old and the gauge was fairly accurate as I recall.
>
> The gauge on the healey was professionally calibrated but it was way 
> off, tending to stick at the full side and then rapidly dropping down 
> to near empty. Recently I calibrated it by removing the sender and 
> adjusting the gauge on the bench but it still sticks toward the full 
> side. When the tank is below 1/2 it will start to read towards the 1/2 
> and 1/4 marks.
>
> What's the issue with getting the gauge to read more accurately? I 
> think it may have to do with the coils and magnet alignment. I think 
> the coils may be out of plumb (due to bending of the case at the nut 
> attachment) which causes the magnet to be too close to the armature 
> assembly.
>
> Has anyone investigated this? Has anyone been able to get their gauge 
> to read more accurately?
>
> John Spaur
> '62 BT7
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---

From: Bob Haskell <[email-masked]>
Date: Thu, 07 Nov 2013 06:05:19 -0500

John,

See the gauge/sending unit articles at 
http://mgaguru.com/mgtech/fuel/fuel.htm

Bob Haskell
AHCA 3000 Mk I registrar
http://www.ciahc.org/registry_3000mk1.php

On 11/07/2013 01:27 AM, john spaur wrote:
> There have been quite a few posts on this issue but none seem to really
> solve the problem. When I first owned an Austin-Healey it was 6 years
> old and the gauge was fairly accurate as I recall.
>
> off, tending to stick at the full side and then rapidly dropping down to
> near empty. Recently I calibrated it by removing the sender and
> What's the issue with getting the gauge to read more accurately? I think
> it may have to do with the coils and magnet alignment. I think the coils
> may be out of plumb (due to bending of the case at the nut attachment)
> which causes the magnet to be too close to the armature assembly.
>
> Has anyone investigated this? Has anyone been able to get their gauge to
> read more accurately?
>
> John Spaur
> '62 BT7
> http://autox.team.net/mailman/options/healeys/[email-masked]

[email-masked]

---

From: "BJ8Healeys" <[email-masked]>
Date: Thu, 7 Nov 2013 06:44:49 -0500

The technique for calibrating a fuel gauge at the mgaguru site is good, but
be aware that the Healey fuel gauge is calibrated at a different maximum
resistance value (90 - 100 ohms) than the MGA gauge (68 ohms).

Also, be aware that if you loosen the adjusting nuts on the back of the
gauge too much and allow the guide foot at the bottom of each threaded post
(on the inside of the gauge where you can't see it) to come out of its slot,
you'll break the coil wire when you tighten the nut again and you'll be
sending the gauge off for professional repair.

Steve Byers
HBJ8L/36666
BJ8 Registry
Havelock, NC USA

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
On Behalf Of Bob Haskell
Sent: Thursday, November 07, 2013 6:05 AM
To: john spaur
Cc: [email-masked]
Subject: Re: [Healeys] fuel gauge calibration

John,

Bob Haskell
AHCA 3000 Mk I registrar

[email-masked]

---

From: "Alan Bromfield" <[email-masked]>
Date: Thu, 7 Nov 2013 12:14:36 -0000

Team.
Bob is referring to an excellent set of articles explaining how the sender
and gauge works, how to repair and how to calibrate. But be careful! After
carefully building a calibration switch as described in:
http://mgaguru.com/mgtech/electric/fg_07.htm
I used it to calibrate my BJ8 gauge (which I had at the time). With a full
tank the gauge read just above half full - dammit!! Unfortunately a couple
of other club members had also used my new switch box to calibrate their
gauges with very similar results.  Strange.
 
Barney Gaylord (MGAGuru) uses the value of 68-70 ohms as the sender
resistance for a full tank. To check my BJ8 I disconnected the Green/Black
wire from the 'T' terminal on the back of the gauge and measured the
resistance with the tank full of juice. It gave 103 ohms! That would explain
why the Guru's 68 ohms reads half a tank or thereabouts.  With a handful of
new resistors I rebuilt my switch box and the gauge could be adjusted much
more accurately.

During my rebuild I had to buy a new tank sender for 'BlueHealey'. It came
from AH4H over here (providers of quality kit to the discerning) and is a
pattern part probably from India. That device had a maximum resistance of
100 ohms too which I measured before fitting.

Be careful out there.
<grin>
  _________________________________________
(______________ Alan Bromfield_______________)
        (_______\____1957-BN4____/________)
                (__tinyurl.com/healeyforum _)

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
On Behalf Of Bob Haskell
Sent: 07 November 2013 11:05
To: john spaur
Cc: [email-masked]
Subject: Re: [Healeys] fuel gauge calibration

John,

Bob Haskell
AHCA 3000 Mk I registrar

assembly.

[email-masked]

---

From: "Alan Bromfield" <[email-masked]>
Date: Thu, 7 Nov 2013 12:16:13 -0000

Very true Steve.
Been there - done that too.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
On Behalf Of BJ8Healeys
Sent: 07 November 2013 11:45
To: [email-masked]
Subject: Re: [Healeys] fuel gauge calibration

Steve Byers
HBJ8L/36666
BJ8 Registry
Havelock, NC USA

[email-masked]

---

From: Chris Dimmock <[email-masked]>
Date: Fri, 8 Nov 2013 01:09:12 +1100

Hi John,
Before you head down the path of recalibrating your gauge, humor me.
Undo the sender unit from the tank, and lift it up a few inches. See if the
float at the bottom of the arm is resting at the rear of the car, or towards
the front.
(Optional: Now crawl under your car, and note that the curved 'sump' that the
float is supposed to sit in when the tank is empty, is at the front of the
car....)
Where is the float resting?
On the flat tank bottom, or in the curved lower 'sump'.
It should be in the sump.
There are a million sender units out there. All look the same - check
yours...
Float should be in the curved sump (at the front of the car) not on the flat
bottom of the tank.
Does the Gauge work now??
No?? Proceed with all the other advice.....

Sent from my iPhone

> There have been quite a few posts on this issue but none seem to really
solve the problem. When I first owned an Austin-Healey it was 6 years old and
the gauge was fairly accurate as I recall.
>
> The gauge on the healey was professionally calibrated but it was way off,
tending to stick at the full side and then rapidly dropping down to near
empty. Recently I calibrated it by removing the sender and adjusting the gauge
on the bench but it still sticks toward the full side. When the tank is below
1/2 it will start to read towards the 1/2 and 1/4 marks.
>
> What's the issue with getting the gauge to read more accurately? I think it
may have to do with the coils and magnet alignment. I think the coils may be
out of plumb (due to bending of the case at the nut attachment) which causes
the magnet to be too close to the armature assembly.
read more accurately?
> '

[email-masked]

---

From: "Healey Bruce" <[email-masked]>
Date: Thu, 7 Nov 2013 12:05:34 -0800

John, you may want to verify if you have an original sending unit or a
reproduction.  My gauge was horribly inaccurate when I bought my car in
2000.  After consulting with Norman Nock, I pulled the sender and the
windings looked like they had been done by a 6 year old with ADD.  Or
perhaps a Labrador puppy.  Understandably, Norman could not give me a core
credit for this cheap POS reproduction unit and I exchanged it for a rebuilt
original.

Now, to the issue of calibration, I put 1 gallon of fuel in the tank and
bent the float arm until it read empty.  Completely full (i.e., up into the
filler tube), it reads about a needle's width shy of full, but that is
acceptable; I would rather have it accurate at the low side than the full
side.

I also carry a dipstick with gallon markers on it, and know that my range is
about 200 miles and reset the trip meter at each fill up.  Hence I have a 3
tiered system for monitoring fuel level.

Bruce
Brea, CA
1960 BN7

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
On Behalf Of john spaur
Sent: Wednesday, November 06, 2013 10:27 PM
To: [email-masked]
Subject: [Healeys] fuel gauge calibration

There have been quite a few posts on this issue but none seem to really
solve the problem. When I first owned an Austin-Healey it was
6 years old and the gauge was fairly accurate as I recall.

The gauge on the healey was professionally calibrated but it was way off,
tending to stick at the full side and then rapidly dropping down to near
empty. Recently I calibrated it by removing the sender and adjusting the
gauge on the bench but it still sticks toward the full side. When the tank
is below 1/2 it will start to read towards the
1/2 and 1/4 marks.

What's the issue with getting the gauge to read more accurately? I think it
may have to do with the coils and magnet alignment. I think the coils may be
out of plumb (due to bending of the case at the nut
attachment) which causes the magnet to be too close to the armature
assembly.

John Spaur
'62 BT7
$12.75

[email-masked]

http://autox.team.net/mailman/options/healeys/[email-masked]
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