caterhamnut Posted May 25, 2006 Share Posted May 25, 2006 Our car is back on the road - hurrah! I pulled over 9500rpm on the way home, and it idles nicely at about 2000rpm - in other words, it is reading double. It is a nice (almost) new Caterham model, with the 3 LED's inside, and the nice tidy plug on th eback, and I sourced it to go with our newer engine/car loom. We are EU2 though. I guess the rev counter is used to wasted spark system - is there anything we can do to make it work properly (although a switch for track day noise tests might be good 😳 😬) www.mycaterham.com here 91,000 miles -1st 1.6k Supersport, '95 Motor Show car Link to comment Share on other sites More sharing options...
Chris W Posted May 25, 2006 Share Posted May 25, 2006 Angus Check the Caerbont (the manufacturer) site for the switch settings on the tacho. There are 6 tiny switches to set on the back of the tacho. The website is here Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
caterhamnut Posted May 25, 2006 Author Share Posted May 25, 2006 Thanks Chris - like many of us Blatchatters, when Mark and I were speaking about it this evening, the first thing I said was 'I need to ask Chris W'!! www.mycaterham.com here 91,000 miles -1st 1.6k Supersport, '95 Motor Show car Link to comment Share on other sites More sharing options...
caterhamnut Posted May 25, 2006 Author Share Posted May 25, 2006 ..of course be prepared for me to come back with some more muppet questions after looking at the link!! www.mycaterham.com here 91,000 miles -1st 1.6k Supersport, '95 Motor Show car Link to comment Share on other sites More sharing options...
Frying Pan Posted May 26, 2006 Share Posted May 26, 2006 The link Chris gave you mentions 'Note A for multiple coil' systems , but I can't see Note A anywhere... I'm guessing your tacho is set up for this, but it doesn't help you know how this is done. I guess you'll need to ring Caerbont, or find someone with a similar ignition system to you to check their settings. Guy See some pictures of the build here. 9000 miles completed! Link to comment Share on other sites More sharing options...
caterhamnut Posted May 28, 2006 Author Share Posted May 28, 2006 b*llocks and b*gger! Taken small rubber grommet out to show switches to find no switches but just a bulb to light the instrument. Label saying EU3 - so I guess it isn't switchable after all www.mycaterham.com here 91,000 miles -1st 1.6k Supersport, '95 Motor Show car Link to comment Share on other sites More sharing options...
Chris W Posted May 29, 2006 Share Posted May 29, 2006 Hi Angus Something's awry here. For the rev counter to read double the rpm, it would have to be expecting a "normal" ignition pulse count but actually receiving twice as many pulses from your engine ie: your engine must be "wasted spark" and the tacho "normal" and not the other way round as you imply in your post (unless I'm interpreting what you're saying incorrectly). It sounds like the tacho is the wrong one if there are no switches on it. I could build a circuit for you which divided the pulses by a factor of two, but it's probably easier and cheaper to get the tacho swapped out for the correct version. Strange that it is marked "EU3" though as EU3 is wasted spark. I can only assume the tacho is incorrectly marked? Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
F355GTS Posted May 29, 2006 Share Posted May 29, 2006 Chris Angus's car is non wasted spark, ie the car has a distributor and a single coil. I completely understand your comment that given the rev counter is EU3 (Wasted Spark) it should be reading 1/2 not double I know Angus aquired the rev counter and swapping it is probably not an option so maybe a suitable circuit as you suggest would be great although we'd need to cut into the loom somwhere to pick up the signal cable Mark Link to comment Share on other sites More sharing options...
Chris W Posted May 29, 2006 Share Posted May 29, 2006 Mark In that case if Angus isn't a wasted spark (!) then the tacho must be set up for 2 cylinders rather than 4. There MUST be a switch somewhere on it - surely? Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
caterhamnut Posted May 29, 2006 Author Share Posted May 29, 2006 Off to the states for a week, but will take a pic when I get back - there is a tiny arrow which may well be some sort of rotational switch.....thanks for the input so far! www.mycaterham.com here 91,000 miles -1st 1.6k Supersport, '95 Motor Show car Link to comment Share on other sites More sharing options...
Peter Carmichael Posted May 30, 2006 Share Posted May 30, 2006 On wasted spark, the tacho would just be taking its signal from one of the coil feeds. In other words, it would be seeing half the firing stroke sparks. The tacho will be rigged to report revs as equivalent to double the count of pulses on its input. In other words, again, the tacho is set up for two cylinders as you suggest. On a normal EU2, this will read double revs. Link to comment Share on other sites More sharing options...
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