rev counter wiring

[rayman]

I have a dashboard out of a dolomite 1500.
I want to fit the rev counter to my herald.
Can anybody tell me the best way to wire it up.

[dollyboy]

should be 3 wires m8.

ground
+ve rpm voltage sensing feed from back of alt
+ve feed to bulb to illuminate the thing, should be part of sidelight circuit.

dolly rev counter is 100mm, not sure if you'll have a suitable hole there to fit it in, nothing a big hole cutter cant fix tho.  the font is different, some people would be quite distraught by that.

job done ;D

[Silvery]

[quote by=dollyboy link=Blah.pl?b=dol,m=1159035180,s=1 date=1159203953]should be 3 wires m8.

ground
+ve rpm voltage sensing feed from back of alt[/quote]

????

Black/ white wire from coil to counter, surely?

[dollyboy]

that'd work...

haha.

i have a prestolite 110A marine alt with a tacho take off built in.  car still currently in bits so havent test it yet, but it should work.

standard loom does have a black/white wire to rev counter, probably does go coil but seeing as my dash is here and the car is about 60 miles away, bit hard to check...

mr rayman doesnt have an existing rev counter by the sound of it, or any existing wiring for rev counter?!

[DavidMyers35]

On the subject, why would my engine not run with the rev counter wire off the coil?  Surely the distributor switches the coil neg on and off and the rev counter just senses this?  Something iffy going on. ??)

David

[rayman]

Nope my herald does not have a rev counter. I will have to wire up from scrath.
Thought some of you dolomte people mite have fitte one to a 1300,{os even put 1500 dash into base model}
Thanks for all the replies. I think i should be able to work it out from whay you give me.
Regards RAY.

[Silvery]

Fitted one in one of my TCs easy enough, also in a 1300fwd...

But I don't feel like digging my spare dash out - Does it have a spade or a phallic connector for the coil wire?

Basically, you need pos, earth, wire from coil. I seem to recall the pos is an insulated spade on the back, the earth is the soldered on spade, and the coil is the phallic whatsit.

The counter takes the feed from the dizzy side of the coil... So I can't see how it would make any difference to the "runningness" of the engine!

[dollyboy]

guys. 

the rev counter feed from the coil or wherever you derive it from is +ve in the context of the dial, this is the black/white wire silvery was on about.  it may appear to be on the negative side of the coil but the whole thing is a big series circuit, so the dial actually ends up as the route to ground for the dizzy.  in absence of the rev counter, the black/white wire should go straight to ground so all you're actually doing is putting the rev counter in series with the coil.  the plain black wire from the back of the dial is the ground for the dial.  the red wire is the +feed to the bulb that illuminates the dial.  the bulb lives in a little push in sleevey thing. this is fed by the sidelight circuit, and the bulb grounds through the case of the dial.

david - the black/white wire also completes the circuit for the coil so you need both sides of the coil connected for a positive output from the HT lead, which is why you'll lose all your sparks if pull either side off.

rev counter is basically a pulse counter, or a frequency meter.

confused?  me too.  (haha)

;D

[Silvery]

[quote by=dollyboy link=Blah.pl?b=dol,m=1159035180,s=7 date=1159297238]guys. 

the rev counter feed from the coil or wherever you derive it from is +ve in the context of the dial, this is the black/white wire silvery was on about.  it may appear to be on the negative side of the coil but the whole thing is a big series circuit, so the dial actually ends up as the route to ground for the dizzy.  in absence of the rev counter, the black/white wire should go straight to ground so all you're actually doing is putting the rev counter in series with the coil.  the plain black wire from the back of the dial is the ground for the dial.  the red wire is the +feed to the bulb that illuminates the dial.  the bulb lives in a little push in sleevey thing. this is fed by the sidelight circuit, and the bulb grounds through the case of the dial.

david - the black/white wire also completes the circuit for the coil so you need both sides of the coil connected for a positive output from the HT lead, which is why you'll lose all your sparks if pull either side off.
[/quote]

I thought all Dolly counters used a spur off the coil, rather than having the coil/ dizzy wire going through them. If you earthed the counter wire then no power would run through the points (OK, some would, but a infinitesimal amount!).

Basically, the ones I'm used to on Dolomites go power into coil, power out to dizzy, and, where fitted, counter. It should be perfectly OK to run without the counter in this type of system!

I do know of counters where the lt goes through them, so removing them from the system does indeed cause a failure in the LT, and hence no spark further down the line, but I've never come across one in a Dolly :) And of course there's diesel counters, that take the feed from the alternator for hopefully obvious reasons. And mechanical ones that have a long cable from the dizzy, IIRC.

The Mini 3 clock instrument cluster uses the same style of coutner as I've found in Dolomites, and that most definately can be run without the counter hooked up, as the City I helped fit a Cooper dash to had all the wiring there but of course no counter to plug it into as standard!

[dollyboy]

hmmm mr silvery, you're probably right, im working from a mental picture of the loom and I'm not driving 60 miles and breaking in to the bodyshop to find out, all i've got here is my dash so I bow to your greater knowledge (and the car parked on your drive)...  ;D

good luck with the fit anyway mr rayman, I think you have the idea...

[Silvery]

[quote by=dollyboy link=Blah.pl?b=dol,m=1159035180,s=9 date=1159303876]hmmm mr silvery, you're probably right, im working from a mental picture of the loom and I'm not driving 60 miles and breaking in to the bodyshop to find out, all i've got here is my dash so I bow to your greater knowledge (and the car parked on your drive)...  ;D
[/quote]

I somehow doubt the 80s blandmobile parked on my drive would be a lot of help reminding me how Dolomite tachos are wired up  :P

Though I suppose I could've either dug out my spare dash, or cleverer still my wiring diagram, but where's the fun in that?

I've just spent far too many precious hours messing around with this kind of thing, some of it has to lodge in my brain eventually :)

[dollyboy]

rescued the the rev counter from my stash, theres 2 terminals for the needle as well as a ground and the +ve to the bulb.

the black/white wire is is the bullet connector, and there are 2 greens that go to the spade adjacent to to it. I dont know where these go to, dont have the rest of the loom here.

the other spade by itself on the dial case is the ground (black wire).

[Silvery]

Quote:

there are 2 greens that go to the spade adjacent to to it. I dont know where these go to, dont have the rest of the loom here.

Are they light or dark green?

Light will be from the stabiliser, dark is just fused ign switched live :)

I have a feeling they're the dark ones, and the reason there's 2 is the counter is they carry on elswhere in the dash harness (could be indicators, can't remember). If they're light ones then same reason for there being 2, but they head off to the fuel and temp gauges.

was about to take a sneaky peek in the Haynes behind me, but it's for the 1300 and 1500, so won't have the rev counter in the diagram.

[rayman]

YIPEE  got rev counter working
white & silver wire to points side of coil.
dark green wire to  pos side of coil.
red wire to pannel light bulbs.
black wire {spade connector on casing} to earth. :)
many thanks for all the replies,  regards RAY.