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Vacuum gauge in restored dash….worthwhile or what?


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Hi

Just in the process of re-veneering the dash in my ‘6, and, having moved / eliminated the instrument light dimmer, I am thinking of a better use of this “vacant “ dash position, and am thinking of fitting a vacuum gauge. It seems engine vacuum is critical for good  running of the PI system.

Your comments would be most welcome.

Also considering alternatives of a clock, or starter push, and will also fit larger led warning lights to replace the low oil pressure and indicator warning lights, both of which are ineffective their present position. I have fitted an adjustable oil pressure  switch which can be set to a higher and more realistic low pressure warning.

Dash refurb generally going well, and enjoying the challenge of sorting the numerous dodgy wiring mods from previous owners.

Some pics below of progress, hope these are of interest.

Cheers

Mike

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Hi Mike,

Rather than a vacuum gauge (so 1970's B))  how about a brake light warning LED's. I had a vacant hole in my 4A dash  and it fitted nicely.

 

On your work bench you have some sheets of 'stuff'   is it plastic shelving type material.  If so what is it called and where can you get it.

I have some but stocks are running low. Excellent for   making formers etc.

 

Roger

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Nice work Mike!

Were it me, I'd add a marine USB/USB-C power outlet on your dash, The number of times we fumble with halfbaked solutions for this is astoundingly regular. I'm contemplating changing all lights in my dash to LED, which would render the dimmer redundant so am comtemplating doing this.

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Mike

I replaced the temperature and oil pressure guages with a combined instrument as used on MGBs, this left a vacant position where I put a clock. I have also removed the mechanical tachometer and replaced it with an electrical one from an XJ6 as I have a 123 distributor,. The Jag tachometer is very similar to the original but does not have the oil and ignition lights.

As you say the oil and ignition lights are pretty much useless, so I used the indicator light position for the ignition light and removed the oil light (there is a guage after all). I then used the searbelt warning light position, which has never worked, for the indicator repeater.

I know it's not very original but the car is my daily driver so it's set up to suit me

George 

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thanks, gents, for much food for thought, USB supply is a distinct possibility.

Roger, the sheet plastic is, I guess, phenol-formaldehyde resin, or  Bakelite as we know it, it came from a laboratory at work which was being stripped out.

its great stuff for worktops, and machines well, and is dead flat, so ideal for clamping veneer.

I guess you might get some from a laboratory fitting company, or recycler.

Good luck

Cheers

Mike 

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I wouldn't remove the oil warning light. If that comes on in front of you are more likely to see and respond promptly to an oil pump failure. Otherwise you rely on actively looking at the oil pressure guage at the time things happen. 

The ignition warning light is less important but the circuit is required to energise the alternator. But your engine won't seize immediately if the fan belt fails or the alternator goes wrong.

 

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I sacrificed the (useless IMHO) eyeball vent between the steering column and door and installed a NOS Smiths vacuum gauge in it’s location.  It looks like it belongs and works quite well.  I don’t have a picture unfortunately, sorry…and won’t for a couple of weeks due to work.

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with you there, Andy, Ill be fitting a 13 mm red led for oil pressure, and a green one for indicator, between the tach and speedo, for the very reason you suggest, and , oil pressure warning at a much higher pressure than the nominal 6 psi or whatever, using the adjustable pressure switch Ive installed.

Its easy to get transfixed on the engine oil pressure gauge, as long as it’s adequate and not very low that’s good enough for me.

Mike

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5 hours ago, charlie74 said:

I sacrificed the (useless IMHO) eyeball vent between the steering column and door and installed a NOS Smiths vacuum gauge in it’s location.  It looks like it belongs and works quite well.  I don’t have a picture unfortunately, sorry…and won’t for a couple of weeks due to work.

That's a good idea. I never drive the car with the top up so I've also disconnected my eyeball vents. Can you post a photo when you get a chance. I'm interested on what gauge face you've selected for the PI system and where you took the vacuum tapping from .

Edited by Mike C
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I’ve never seen a modified dash that was better than the original. Mostly they get ugly real quick.

More features and bits and bobs and different locations …but then it’s a custom car mess up; you’ve got to keep with the original layout - a thing of beauty and designed by the Great British mind (and some other minds) which delivered the car. It works as it is. USB in a TR6, that would part erase the reason for driving it over my BMW. Dials in the place of vents, why?? Put a TV where the door windows are, you wouldn’t.

Hold back, and let it be a TR6, inside and out. 

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Nce work on the veneer.....I would prefer an Air/Fuel gauge rather than Vacuum, providing you are prepared to fit the sensor into the exhaust pipe..

Edited by Malbaby
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I'm probably  old school, but my MU fuelling curve is set by the vacuum, and I can  diagnose  fuelling faults a lot of others from the readings and behavior of a vacuum gauge, using 1960's style engine analysis. A permanently connected vacuum gauge would be really useful to me.

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6 hours ago, Mike C said:

That's a good idea. I never drive the car with the top up so I've also disconnected my eyeball vents. Can you post a photo when you get a chance. I'm interested on what gauge face you've selected for the PI system and where you took the vacuum tapping from .

I’d be happy to when able. I have a NA model with carburetors so my connections wont be the same as a PI model but i can definitely still do so…

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2 hours ago, charlie74 said:

I’d be happy to when able. I have a NA model with carburetors so my connections wont be the same as a PI model but i can definitely still do so…

Thanks. My PI inlet manifold will be working  with lower vacuum levels than yours but that's only a matter of finding a suitable gauge.

For checking the vacuum in the garage I use the brake booster hose but I'm sure I can find another  existing point  or tap in a nipple if needed.

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An air/fuel gauge…hmmm. 

I bought one awhile ago for my MG, but it seemed very unstable, probably because I stuck  the sensor up the exhaust.

I do have a spare exhaust front pipe ( it came fitted with a horrid exhaust sports silencer, sounded like a bad day at Santa Pod)

which is offered free to anyone near York to collect, otherwise soon to go in the skip.

Need to decide soon, just milled the keyhole slot for the glovebox lock.

All part of the fun

Mike

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19 hours ago, mleadbeater said:

with you there, Andy, Ill be fitting a 13 mm red led for oil pressure, and a green one for indicator, between the tach and speedo, for the very reason you suggest, and , oil pressure warning at a much higher pressure than the nominal 6 psi or whatever, using the adjustable pressure switch Ive installed.

Its easy to get transfixed on the engine oil pressure gauge, as long as it’s adequate and not very low that’s good enough for me.

Mike

You could always wire the pressure switch to activate a relay that powers the fuel pump.   Pressure below 20 psi and the pump cuts out.    I had a Metro Turbo with that system that had a dud pressure switch which meant the fuel pump would cut out when the engine was good and hot and idling.   

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On 10/7/2023 at 6:26 PM, BlueTR3A-5EKT said:

You could always wire the pressure switch to activate a relay that powers the fuel pump.   Pressure below 20 psi and the pump cuts out.    I had a Metro Turbo with that system that had a dud pressure switch which meant the fuel pump would cut out when the engine was good and hot and idling.   

There was the same fitted to Series 2 XJ6. I had one that occasionally wouldnt start as the switch was duff so no fuel pump. Bridged to earth and never worried about it again!

Stuart.

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5 minutes ago, mleadbeater said:

a fuel cutout switch/ relay sounds good, but how would you start the engine?

it would require an override or timer, and what happens when you stall?

ill stick to a decent warning light.

Mike

It has an override wired with the starter motor, bit like the ballast bypass for the ignition coil..   When it is cranking the fuel pump is set to run.

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7 minutes ago, BlueTR3A-5EKT said:

It has an override wired with the starter motor, bit like the ballast bypass for the ignition coil..   When it is cranking the fuel pump is set to run.

cant see any override on the wiring diagram, (which is a non-ballast diagram) the pump is fed off the same supply , via the ignition switch, terminal 2, and fuse terminal 1 , as the dizzy.

Im still trying to find a correct wiring diagram for my ‘73  car, does such a thing exist ?

 

Anyway, car electrics are getting far too complex for me, they’ll be fitting automatic steering and brake application device’s to moderns…oh, they already do !

Rant over, cheers

Mike

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