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MG Midget and Sprite Technical - electronic ignition and tacho

Hi,

Recently cured no spark to plugs. Discovered it was the pertronix elec. ignition unit not working. I have replaced this with a unit from Simon BBC, which works great, EXCEPT the tacho is not moving! The tacho worked well with the Pertronix, and the new unit is same "Hall Effect" principal.
Any ideas? (apart from the tacho being goosed).
Car had not been started for 18 months, I've had an auto electrician check earths, ignition supply etc.
aj robinson

read the pertronix trouble shooter sect of there website, they mention a similar situation and how to resolve it....it may not be the cure, but it will get you started with as clue for where and how to procede

also check to see if the chip your using has a 800 tech department...Im sure its in india, the guys name will be bob, and says he lives in iowa...lol

and you might try a genral google search of the topic

also try youtube...suprisingly Ive found many an answer to lifes mysters there

it seems to me it has to do with the pulse that the chip gives off cant be read by the electrics in the tach....you may have to purchase a later model tach...agian I just dont know, and probably shouldnt even be commenting on this topic, Im just hoping to provide additional thought provoking ideas on where to look

I ***think*** the tach is okay if the engine is running...the tach acts like an expensive circuit breaker, if you fry the tack the enine wont run... but that would depend on the wiring set up... I know mine wont, If I disconnect one of the +/- tack wires at the tach...but my wire system is a mess of hacks and bodges....so who knows if thats acurate info or not
Prop

Thanks Prop,

I've heard similar stories about changing to a later tach, but that doesn't explain why the tach worked with the Pertronix but not the BBC.
Had a conversation with SIMON BBC today, and they have had a very few problems, but then no feedback from customers!!
Andrew
aj robinson

The tacho works by picking up the pulsing of current through the ignition wire to the coil.
Electronic ignition smooths out the pulses hence no tach. If you can't get it working this guy can convert your tach to work from an extra feed from the coil, with a quick turn-around.

http://www.thegaugeshop.com/

No connection juat a satisfied customer
R Fowler

Thanks for the info, I have e-mailed him tonight. I will let you know what happens.
Andrew
aj robinson

I guess it doesn't really explain why the tacho worked with Pertronix originally! Just good luck perhaps?
Andrew
aj robinson

I guess the Simon BBC unit smooths out the pulses better than the Pertroinx kit.

No idea why.
R Fowler

I had a problem with the Pertronix and my tacho. Mostly the needle just jumped around all over the place. In the end I bought the RVC2415 variant on EBay and that resolved my problem. The tacho works perfectly now :)
TonyJHamilton

Im agreeing with R fowler
Prop

Thanks Guys,

Looks like there may be an easy-ish fix! I will let you know. No doubt the wiring for the tach will have to change. Think I've seen something on the internet message boards for the Lotus Elan.
Regards,

Andrew
aj robinson

Posted 19 September 2010 at 03:56:56 UK time
Prop , And The Black Hole midget
Im agreeing with R fowler

God, now I'm worried. please disregard all my posts!!
R Fowler

R.

You were a little short on the extorsion/blackmail money this week...LOL
Prop

I had this problem with a 123 Distributor. I had to supply the dizzy with a power feed that did not go through the tachometer. I have a wiring diagram that shows how it was for the 123 but can't upload it here for some reason. Can email if you want. Chris
Chris H (1970 Midget 1275)

Hi Chris,

That would be fantastic.
Regards,

Andrew
aj robinson

Hey Chris,

Can I please have a copy also... Thanks

Propaper (at) Mchsi (dot) Com




.
Prop

Chris H

Could I have a copy please

alan.cotterill@btinternet.com

Thanks, Alan.
Alan cotterill

Could I have a copy too please.
GF Greg Smith

GF Greg Smith - let me have an email address and I will send you a copy. Chris
Chris H (1970 Midget 1275)

Hi Chris, any chance you could forward a copy onto me please:

woboff at yahoo dot co dot uk

Thanks
Mark
Mark Whitmore

This thread was discussed between 17/09/2010 and 11/10/2010

MG Midget and Sprite Technical index

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