17 replies to this topic

[Rufus The Red Mini]

Has anyone used a cheap spark plug tachometer? I've tried two as my 1988 mini city doesnt have a rev counter but cant get an accurate reading. Have lost the instructions and have tried to find the manuals online to check I have the right cyl/stroke combination but had no luck. When ticking over it ranges from 400 to 4000!! Please See photos of the two I have. If not how easy is it to fit a standard rev counter?
Thanks in advance.

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[DeadSquare]

If by "Standard" you mean the 50 year old Smiths it is just a matter of a hole through to the engine bay, a bracket to mount it and connecting 3 wires and maybe an earth.

[mbolt998]

Has anyone used a cheap spark plug tachometer? I've tried two as my 1988 mini city doesnt have a rev counter but cant get an accurate reading. Have lost the instructions and have tried to find the manuals online to check I have the right cyl/stroke combination but had no luck. When ticking over it ranges from 400 to 4000!! Please See photos of the two I have. If not how easy is it to fit a standard rev counter?
Thanks in advance.

I've got something a bit like that, very cheap off Amazon (for setting the timing and idle speed). It also seems to be a bit unreliable occasionally seeming to be off by what seems like a factor of 2. The only thing I can suggest is try a different plug lead and just disconnect and reconnect a few times until the reading is in the right ballpark. If it's close to the right reading it probably is right is my optimistic assumption.

 

I wonder if there's a phone app that can tell you rpms just by listening through the microphone.

[DeadSquare]

 

Has anyone used a cheap spark plug tachometer? I've tried two as my 1988 mini city doesnt have a rev counter but cant get an accurate reading. Have lost the instructions and have tried to find the manuals online to check I have the right cyl/stroke combination but had no luck. When ticking over it ranges from 400 to 4000!! Please See photos of the two I have. If not how easy is it to fit a standard rev counter?
Thanks in advance.

I've got something a bit like that, very cheap off Amazon (for setting the timing and idle speed). It also seems to be a bit unreliable occasionally seeming to be off by what seems like a factor of 2. The only thing I can suggest is try a different plug lead and just disconnect and reconnect a few times until the reading is in the right ballpark. If it's close to the right reading it probably is right is my optimistic assumption.

 

I wonder if there's a phone app that can tell you rpms just by listening through the microphone.

 

 

If you rev the engine well, the valves bounce at 6,000rpm

[68+86auto]

What is the pickup like? for some reason I think I remember reading something about these being like a wire and to wrap it around a few times or something like that.

[mbolt998]

What is the pickup like? for some reason I think I remember reading something about these being like a wire and to wrap it around a few times or something like that.

That sounds like a very good idea which I will try to remember for the next time i use it. It's just a kind of crocodile clip.

[Rufus The Red Mini]

[quote name="DeadSquare" post="3749063" timestamp="1690661019"]If by "Standard" you mean the 50 year old Smiths it is just a matter of a hole through to the engine bay, a bracket to mount it and connecting 3 wires and maybe an earth.[/quote
I just want something simple so 3 wires should be fine!!!

[Rufus The Red Mini]

What is the pickup like? for some reason I think I remember reading something about these being like a wire and to wrap it around a few times or something like that.

That sounds like a very good idea which I will try to remember for the next time i use it. It's just a kind of crocodile clip.

You just wrap the wire around the spark plug but have to set no of cyls and no of sparks per rotation. But dont know if that s1 s2 s3 on one end p1r1 p2r2 etc on the other one!!!

[gazza82]

You might be able to find a simpler rev counter than a Smiths .. Speedwell did one with two wires that simply connected to the two coil terminals.

Edited by gazza82, 30 July 2023 - 01:25 PM.

[Rufus The Red Mini]

Having spent hours yesterday, and snapping the wire off one of them, I gave up. It seams if the wire goes anywhere near any other cables if goes all over the place. The only way I got a reasonable reading was holding it in the air in front of the car with a tight wire. So no good whilst driving!!. So went on amazon and got one with 4 wires- positive, negative, one to the neg on the coil and one for backlight- which I probably wont use.

[Rufus The Red Mini]

Just got rev counter. Came with 5 wires. Instructions below. I get red pos black neg and green to coil. Might be a stupid question but Why is there a white to ignition? Do I need it? If so what wire can I link it to as I have no spare terminals in the fuse box? Also can I do away with the yellow light switch ?

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[gazza82]

Red will be perm live and unfused, white ignition switched/fused from that diagram.

You'll need the white to power the tacho when you turn on the ignition switch but it's odd to have two power feeds ..

[smurfomatic]

Presumably, yellow wire is for the gauge ilumination so needs connecting to the 12V feed from the headlight switch?

[gazza82]

Presumably, yellow wire is for the gauge ilumination so needs connecting to the 12V feed from the headlight switch?

Didn't bother mentioning that as OP said he might not bother with it ..

So to me it looks like there is a red-black circuit to perm live ... and I've no idea why you would want that on any accessory but must have some purpose .. and the white-green which effectively mimics the coil wiring and picks up the pulses as the coil works (white to ignition live and green to the distibutor).

[Rufus The Red Mini]

I did mention that the fuse box was full and had no spare terminals. Is it an issue connecting it to something like the positive to the radio which has an inline fuse and runs along where the rev counter goes?