• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

gas gauge

Share this page

Do you remember the electronic SU failures not too long ago?

OH Yeah !! the diode failed and burnt a hole in the cap.
However"
,today Ray:----:highly_amused:

:devilgrin:
 
Last edited:
Someone have tried the TSV application to the distributor as arc suppressor ? I am interested for my MG TD points
 
andrea said:
Someone have tried the TSV application to the distributor as arc suppressor ? I am interested for my MG TD points
Click to expand...

In theory, it might work. However, there are a couple reasons it probably wouldn't, at least not without undesirable side effects. IIRC, a TSV is a form of Zener--or 'avalanche' or 'breakdown'--diode. Zeners are sometimes used to protect against overvoltage in circuits; when the set voltage is exceeded a Zener lets current flow through a fuse, blowing the fuse and causing current to stop flowing. Used in a fuel pump, when the 'breakdown' voltage is reached the TSV shunts the high voltage produced by the coil's EMF field collapsing back into the coil--instead of through the points--hence reducing arcing. Used in a distributor, a TSV would probably shunt the current back through the coil, which could upset timing and the production of quality sparking. Also, I believe the condenser used with points is also used in a sort of timing circuit to regulate the current flow to the coil as well as for arc suppression (if diodes would work in a distributor, I'm sure they would have been used; probably around the time they began to be employed in SU fuel pumps).

Points 'technology' quit evolving, oh, probably in the 1910s (magnetos have points, too). If you're not happy with points--either because of the extra labor required to service them or because quality points are getting hard to find--install a Pertronix or other suitable points-less system. Easy to install, and basically bulletproof; we have a Pertronix in 5 vehicles and never had any issue with them. We have one in our '56 BN2, and it doesn't even require the magnet ring that has occasionally failed; the unit is sensitive enough to sense the rotation of the cam lobes. Pretty cool in my book. And, FWIW, I tried a TSV in an SU fuel pump and it didn't work any better than diodes (I know some have had success with them, but I didn't). Electronic is the way to go if you do any serious driving.
 
Last edited:
Thanks, Ray. One thing I neglected to mention is that I believe the TSVs are not polarity sensitive, which is an advantage over a regular diode which, if installed backwards will prevent the pump from operating.
 
My gas gauge is reliable and steady as a rock. It does have a new sending unit which I am sure helps. It has a different problem.

It gets stuck at the low and high ends of the scale. For example,

Turn on car. Gauge remains stuck on E. Rap it with your knuckle and it will jump to the correct spot.
If you fill the tank to full, it will remain stuck at F until the fuel drops and you whack the gauge.

I take this as one of those non-destructive endearing quirks of the car but it would be nice it if worked right. I have cleaned the grounds and contacts at both ends. Any other ideas?
 
I've not had my gauge stick on high, but it does stick on E. I tap it with my finger tip. It's probably in the gauge itself. You could try cleaning & lubing, or continue to tap.
 
My gas gauge usually sticks reading "full". A quick tap on the glass will bring it to attention.
It also reads 1/8 when the tank is empty.
Don't ask me how I know.
Yes, my co-pilot was with me.
 
I had mentioned tapping the gauge previously but what's so odd is that later on if I park for an extended time (i.e. for a show, etc.), the gauge responds without tapping when I start the car. The other gauge condition I noted is that it will sometimes fog up when first started and then clear up. No other gauge does this, only the gas gauge.

Lets face it, our LBCs are quirky but it's these oddities that give them the personality and character we love.

Ray (64BJ8P1)
 
Bob_Spidell said:
In theory, it might work. However, there are a couple reasons it probably wouldn't, at least not without undesirable side effects. IIRC, a TSV is a form of Zener--or 'avalanche' or 'breakdown'--diode. Zeners are sometimes used to protect against overvoltage in circuits; when the set voltage is exceeded a Zener lets current flow through a fuse, blowing the fuse and causing current to stop flowing. Used in a fuel pump, when the 'breakdown' voltage is reached the TSV shunts the high voltage produced by the coil's EMF field collapsing back into the coil--instead of through the points--hence reducing arcing. Used in a distributor, a TSV would probably shunt the current back through the coil, which could upset timing and the production of quality sparking. Also, I believe the condenser used with points is also used in a sort of timing circuit to regulate the current flow to the coil as well as for arc suppression (if diodes would work in a distributor, I'm sure they would have been used; probably around the time they began to be employed in SU fuel pumps).

Points 'technology' quit evolving, oh, probably in the 1910s (magnetos have points, too). If you're not happy with points--either because of the extra labor required to service them or because quality points are getting hard to find--install a Pertronix or other suitable points-less system. Easy to install, and basically bulletproof; we have a Pertronix in 5 vehicles and never had any issue with them. We have one in our '56 BN2, and it doesn't even require the magnet ring that has occasionally failed; the unit is sensitive enough to sense the rotation of the cam lobes. Pretty cool in my book. And, FWIW, I tried a TSV in an SU fuel pump and it didn't work any better than diodes (I know some have had success with them, but I didn't). Electronic is the way to go if you do any serious driving.
Click to expand...
Hi Bob
I have the TSV on my SU fuel pump (on the MG TD) I am very satified , all works OK-(TSV are bidirectional Type)
Your good explication on the distributor application confirm my doubts on TSV distributor apllication- however I have 10 TSVx 1$ - on a box, and the application is easy to attempt, so probably i will try it on the MG distributor,i revert asap with the results (actualy here, weather are stormy and cold, not agreable for experiments)
On my AH i have the 123 Electronic Distributor-I can confirm the rialibility
I have tried to upgrade the MG TD to Pertronics but the experience was NOT positive - probably my old mechanic BORIS is not Electronic inclined
 
Back
Top