Smiths tacho query

[Steve R]

Ok Tony, I'll bring the strobe into work tomorrow.

Yep, finally on the road     I even drove it in to work today.  Fingers crossed the rain holds off!

Great to be road legal at last (...well sort of... still need to get a front number plate!).

Steve.

[Flappa]

Tony,

Excuse the sales pitch but I have an MBE lead for sale in the parts for sale section.

SBD want £32.50+VAT + dely.

When I bought the parts to make my own recently I ordered enough to make another.

You can have it for £20. Then you should just need a serial to USB adaptor (about £12) and you're connected.

I live in Rednal (M42 jcn 2) so not far from you.

[lukeyboy]

Is this only a problem for the Zetec models?

My white Smiths dials arrived yesterday and I'm to install them on a Weber / Duratec install.

I will have to check, but I could have sworn I only had 4 dip switches to set!!

[kevip6]

Hi,

I have the Smiths gauge connected to the Alpha ECU output on my 2litre Zetec.

I had to set mine to 6 cylinders due to it being wasted spark and my gauge shows pretty much exactly the same RPM as the SVA machine.

I left the Pot adjuster alone.

HTH

[Tony Hughes]

As in my earlier post - 6 cyl setting sounds right at idle.  I'll try to check it at higher revs and see what we get using Steve's stobe thingy.

What's the logic for 6-cyl setting working anyway?

Tony

[Tony Hughes]

Flappa,

Thanks for the offer - may take you up on that if I can't fix it without spending any more money!

I know Rednal a bit - used to work at Longbridge in late 70's (yes - I am that old ....)

Cheers,

Tony

[Flappa]

No probs, Blacknblue has said that he wants the lead in any case.

If you check in the destructions for the tacho, I'm sure that I read that it expects 2 pulses/rev for a 4 cyl engine (3/rev for a 6 cyl, & 4/rev for an 8 cyl). Presumably this takes care of the wasted spark?

If you set it to 6 cyl it will expect 3 pulses/rev but only get 2 (4 cyl), so it should read lower by 33%.

Does that make sense

[kevip6]

I agree i can't work it out either?  

But it does seem to work, it matched the SVA machine at idle and all the way up to over 3000RPM when they were doing the emissions tests? So i would suspect if it's accurate at 900RPM and 3000RPM then the rest should in theory be fine as well?

I've been trying to think how this works out based on 2 packs firing 2 cylinders each and i've found sites on the internet stating a 1.5 ratio on wasted spark but have so far failed to find an explaination?

[Morbius]

I found that the only way I could get mine to read accurately was to use easymap to view the actual revs, hold the engine at 2000rpm, then turn the pot on the back of the rev counter until it read 2000rpm also (This assumes the dip switches are set right of course)

Paul

That is what I did with mine to work with my Emerald ECU.  I used the Diesel setting and tweaked the pot to agree with the revs that the ECU displayed on the connected laptop.  It reads a bit high at low rpm, but is not too far off on the rest of the scale.