converting tacho pulse

[pozman]

i recently put a 7mgte, six cylinder, into my bundy, 4 cylinder

i want to run std tacho, can i get a gadget to convert my 6pulse feed to a 4 pulse tach?

or can the tacho be modified to take 6 pulse

where would i get this done?

thanks paul

[DamTriton]

Have you tried it anyway??? It may well be a tacho signal from the computer that is one per RPM (regardless of engine type) rather than 4 or 6 every two RPM. This would allow the manufacturers to use different engines in same bodies with little drama.

If you try it the tacho should read OK (~700 RPM), or read ~1100 RPM at idle if it isn't OK. Shouldn't damage anything by trying....

[-Scott-]

Just hook it up anyway - passengers will be really impressed if they see it revving to 9000rpm!

Years ago I read a story about a Merc based super sports car (all wings & spoilers, with a turbocharged V8). The engine was built to run to 9000rpm, but the driver was a "traditional" bloke who didn't like revving an engine past 6000rpm, much to the engine builder's frustration. Somebody proposed "gearing" the tacho to read low - but I don't recall if they did it.

[pozman]

lol thats funny

yeah i'll hook it up and give it a crack, if its not right i'll need to change it as the tacho only goes to 7, old red line only being high 5's, the 7m run 7 grand easy

i have a feeling that it may not work as the bundy only ever came in a 4cyl and the supra only ever a 6cyl

[chimpboy]

These guys could probably do it:

http://www.ottoinstruments.com.au/

I doubt just using it anyway will work, but worth a try I guess. Other options are to find a 6 cyl tacho that fits, probably from another toyota, or to swap/modify the face of the dial, ie where it currently says "6000" change it to "4000", with a dial from another speedo or with some nice inkjet printing.

Or... find a 6-cyl tacho with the same sweep and put it in the housing from your current tacho.

These options are all fiddly but not TOOOOO fiddly imho. Depends what the instrument guys want to charge you.

I would start by going to a pick-a-part and trying to find a 6-cyl tacho that fits first.

[chimpboy]

eg. http://cgi.ebay.com.au/FJ-60-SERIES-TOY ... .m20.l1116

... looks like it might be almost the same...?

[pozman]

yeah theres an idea, get one out of a fj7x or fzjx might just work

[killalux]

Hey,
Yes otto instruments can do it, I have had a couple done there. From memory it was around $100.
Steve