Escort Twin Cam Rev Counter

[curtis]

I have just bought a MK1 Ford Escort Twin Cam.
The electronic rev counter reads far too high. At this stage I don't know if the previous owner has "fiddled" with anything.
Any ideas where and what I should check?
Thanks

 

[aeronca65t]

Congrats on your purchase.

If your car has a "universal" (non-standard) tachometer, it may have a switch on the back for different numbers of cylinders (i.e.- "2,4,6,8"). I that switch is set wrong, revs will read wrong. If your car has the standard tachometer, I can only suggest that you check the wiring to it to see if something has been altered.

 

[curtis]

It is the standard tacho.. I'm gathering ideas before I start /ubbthreads/images/graemlins/smile.gif
Pic attached, of the car.

 

[coldplugs]

Has the engine been converted to an electronic ignition?

 

[curtis]

Good point. But No.

 

[coldplugs]

This might trigger a thought...

www.lotuselan.net/publish/bouncing_tach.shtml

 

[DrEntropy]

Curtis, you DAWG!!! I opened that attachment expecting to see a tach... Is THAT the car you bought?!?!

...'scuse me while I roll my tongue back up into my mouth...

It is likely a Smith's impulse tach, yes? Check to see if there's a voltage regulator under-dash. If there is (and I believe there should be) that's where I'd start. It should have a 10V steady output, not 12V. dklawson (forum member) has authored some excellent articles on the subject.

 

[mikespain]

Hi-Had the same problem on a lotus cortina I was rebuilding for someone and here goes- if you look on the back of the rev counter there might be a rubber plug which gives access to the adjustment of the rev counter-just by the bulb for illumination,if not take the bulb out and look inside and you should see a white adjustable potentiometer.If there is no plug carefully calculate the position of the potentiometer and VERY carefully drill a hole big enough to allow a small electrical screw driver to enter the adjustment slot in the potentiometer(that is if your not lucky enough to be able to get the proper plastic screw drivers that they use on electronic repairs)Now connect the rev counter up and also connect a timing light with rev counter incorporated and adjust your rev counter to the timing light one seal the hole with a bung or tape and job done

 

[curtis]

That sounds very interesting Mike. Thanks.
Just a point, I have been in touch with the previous owner and he said that the problem arose after he had a set of 4 Lucas 700 lamps fitted and a Retrotrip and rally Timer.
I have re wired the Retrotrip and rally timer correctly but haven't looked at the lights yet.
They run through two relays , two lamps each, and one doesn't work. When you switch it on it blows the fuse.
That's just a bit of background. Obviously I will have to find the cause, but would this info alter your view on the adjustment?
Finally, Mike, I follow most of what you say but I can't grasp the timing light instructions! Could you describe it again. Thanks

 

[smcmanus]

I'd connect a tuning tach to the coil "+" terminal and adjust your dash tach to match the tuning tach. Perhaps mike has a fancy timing light with built-in tach.
Have a good day
Steve

 

[mikespain]

yep I was referring to a timing light with built in tach, but any clip on tach will do,to have a reference to adjust your tach to.As to the tach playing up after adding the retrotrip and rally timer, if it has done any damage to the tach then doing what I suggest will not harm it anymore,and if it doesn't work then the tach will have to be repaired.As to the problem of the lights ,it has to be that at some point the wires have been crossed and the live side is going straight to earth,either the bulb is wired wrong or the relay or the switch. good luck

 

[mikespain]

Hi curtis ,how's things going with the escort?

 

[Super 7]

Those old Ford Tachs are notorious for reading high. Let us know if you figure out how to fix it. They never sold those cars here in the US.

 

[curtis]

I haven't forgotten you guys!!
Suddenley there are all kind of electrical problems and I am
trying to work out what has been done over the years by previous owners. It's a nightmare and the rev counter is a small part.
Will report back when there is some news.