Rev counter wiring help

[Allan NZ P5b]

Have entire dash apart to install coupe gauges in my saloon all going well except rev counter ( the reason for the change) wiring diagrame shows white feed from ignition going to a terminal on gauge then to a second terminal
and feed from ballast resistor going to another terminal.
Plus counter grounded for pannel lights and I presume gauge its self though mounting I have only 2 teminals on my rev counter 1 spade conector I presume is feed from ignition and one brass threaded rod with nut I presume for feed from coil via ballest resistor. I cant find a third conection and am not sure if spade is +ve feed or coil feed and if brass threaded conector is coil feed and why I have no third conector.
Help please.
Urgent as car is disabled and I don't want to put together to pull all appart again regards

[Phil Nottingham]

:)The wiring diagram is misleading on this type of Rev counter there are only two terminals.

The Lucar one goes to the 12v side of the coil or ballast resistor.

The 4 BA "terminal" should have a special nylon clip that forms a 1/2" loop in the ignition supplied feed wire. If this is missing you will have to improvise as the loop is important - it must be some form of induction - it is not actually connected

[glow=red,2,300]Note the loop is completely insulated ie do not strip the cable![/glow]

[Allan NZ P5b]

by 4 BA "terminal" do you mean one like this I found on an mg site.

I have the post that is all. The instructions on this pic were on it are they correct as I am still unsure.
I get the Lucar ( spade Terminal) goes to ballast resistor or + side of coil.
The loop of wire comes from ignition terminal 2.
Then loops around next to the post ( not around it ) I will have to fabricate something. And ends where conected to what?
Thanks for all the help Phill but this has now got me confused. Are you sure the spade conector is not the power feed supply.

[Phil Nottingham]

Yes - thats the arrangement and either way round will work - if the feed is green this may go via a fuse so this should not also feed the coil

[Allan NZ P5b]

Still confused please read my post above and clarifie the answers.
Thanks for all the help
lucar ( spade) goes to power or coill
induction wire wone with loop as above runs from ballest resistor to ingnition is this corrects.
Sorry must be having a blond day still unsure.

[Phil Nottingham]

::)I think by logic - the looped terminal is the ignition feed to the coil via the ignition switch.

A FURTHER ignition feed from the switch goes to the Lucar connector.

By the way - the instrument is incredibly unreliable and the transisters contained therein are well past their useful life.

Still it looks good. ;D

My Coupe is very sensitive to ambient temperature - the hotter it is the higher it reads.

Why does no-one else comment on this?

[Allan NZ P5b]

thanks phil will let you know how I get on regards
Allan

[Allan NZ P5b]

All done.
Well sort of.
The gauges are all in the right position and wiring is now complete. ;D
Made alterations to loom using correct colour coded wires from an old loom I pirated for bits and pieces. Hardest bit was wiring for the dash lights lots of 2 way split offs.
Replaced the timber behind the pod with freshly refinished piece as this had never been done. ;D
Reglued vinyl to binnacle so doesn’t look like jaws when you take off dash panel.
Mounted pods under main binnacle I had to drill new holes to take the mounting brass inserts and then glue in place with epoxy for the 2 additional pods.
I think my pods maybe ½” further out than original put hey it’s not original.
I put them where I thought they looked best.
The amps, Fuel and water are all working. Oil gauge works but I have no sender at present will attend to that latter.
Rev counter still causing grief and eventually established that inductively coupled Tachometer is not compatible with my Ignitor II electronic points unit.
I need a Current sensing tachometer, which will be more reliable and accurate. B****r!!!.
Some investigating today has led me to a clever classic car instrument technician who will Take mine apart clean remove components from the circuit board and resolder new thingies on, reassemble and test all for about $60.00 NZ.
Next best price was about $300 to stick new guts in old case.
But he is a busy boy and can’t look at it until end of next week so will take to him then. Will let you know how it all goes.
Thanks Phil for all your help

Regards

[Phil Nottingham]

:-[Bad luck - well as I said they are only for show anyway

[Allan NZ P5b]

I finally got my rev counter back, The instrument guy had a new old stock vdo Current sensing tachometer so rather than mess about with mine he put brand new guts in the counter keeping original case,needle and face for the original estimated price to change mine over, I have refitted this evening and it works a charm seems very accurate, and fills the ugly hole I have had in dash since fitting other coupe instuments in coupe pods under main binicle. I was getting sick of looking at a bunch of wires, The gauge looks completly original as it should.
Very happy camper tonight

Regards

[Allan NZ P5b]

here is a link to pitures of the guages installed along with new wheel
roverp5.proboards31.com/index.cgi?board=Roversfromaroundtheworld&action=display&thread=1106748570

[Deleted]

So I checked and rewired everything. The only difference to the original layout is that I use a blue Bosch coil without ballast resistor (but even installing one does't change anything).

The rev counter shows some 1700rpm when ideling so about two times the realistic figures.

Am I right that the instrument some sort of reads the number of interruptions in the current by induction via that loop in the wiring between the ignition switch and the coil.

So twice the reading you would expect if you use a 4 cyl. instrument on an 8 cyl. engine. But mine is marked "8 cyl"

I would suspect the instrument if the reading was somewhat irregular, but as it reads nearly exactly double I hope that the fault might be elsewhere.

But where? Any hints?

Michael