Rev counter/tach on Amazon

[tomti]

Hello all,

A question for you all to ponder (and preferably answer )...

After a frustrating session trying to set the mixture on my twin SU carbs using a Gunson Colortune thingy (and failing with one of them), I've come to the conclusion that it might be a good idea if I have a look at the jets, needles, floats and so on inside the carbs to make sure that they're all up to scratch - the amount of crud on the surface of them makes me think they've not been serviced in a while...

I've got the carbs off the engine and have started stripping them down and cleaning the various bits. I intend to get hold of a service kit from Burlen or somewhere similar and replace various gaskets, jets and so on.

However (and here's the question) - in my Haynes manual and elsewhere, it mentions setting the idle speed when I replace the carbs by altering various screws etc. until the revs are 'right' (about 800 idle, I think - obviously I'll be more precise when actually doing it ).

My Amazon doesn't have a rev counter - I've seen some that do but it's an aftermarket thing and usually far fancier than I require.

Does anyone know whether a) it's possible to get hold of a cheap and nasty tach that I can use for workshop purposes, and b) how one would go about attaching it to the B18 in my car?

Many thanks.

-Tom

[Andrew (UK)]

Get an automotive multimeter, about 15 quid or upwards. This will do rpm as well as dwell angle. Setting the dwell is a much more accurate way of setting the points than using a feeler guage. Attach to the low tension feed from the coil, possibly easiest done at the distributor (especially if you have the armoured cable to the ignition) but I don't know about Amazons and I haven't actually done this myself on my 1800S yet.

HTH,
Andrew

[tomti]

Andrew - thanks for that. I'll get hold of one of those gizmos and give it a go.

[amazondean]

Actualy if you don't get a multi meter you will hopefully be able to set it by ear. If you can succesfully rebuild and fit and balance the carbs properly you will find that setting the 800 rpm will be the least of your worries. If everything is set right you will be able to guess the right revs by ear. Basicaly it will be as slow as possible that shows an even beat.

Get youself a carb ballencer to help set the tickover, although contrary to popular belief, These things do not balance carbs properly, they just set the idle balance. Once you blip the throttle, that setting is finished with. To balance the carbs you alter the shaft setting between the carbs and as you rev it up using the throttle lever on the carbs, you can see if the pistons move up and down evenly.

Dean