chocolate_supra

Ah, thanks for that! I was afraid someone might've stuck the wrong carbs on this engine. So do the adjustments that apply to the earlier carbs still apply? Such as bottoming it out then turning 2.5 turns back out to start with?

I've been doing all sorts of reading on forums, articles, and my repair manual about how to adjust the carbs on my 240Z. I'm running into a problem, though- the mixture nuts that I see on all the articles and in the repair manual look totally different from mine. As far as I can tell I have the early dome-top SUs, but these mixture disc-things on mine don't even look like what's on the later flat-top SUs. I'm obviously confused. Here are what I see everywhere: And here are mine. As you can see, where the mixture nut would be is just a disc. This is really halting my tuning process, as the standard mixture setting to start with is about 2.5 turns from bottomed out, while my disc-things only turn about a half turn before hitting a notched stop-point. I'd really like to know what's going on, especially if these turn out to be something other than 240Z carbs.

Get this- I got the tachometer unit out of the enclosure and found that one of the internal wires coming off a resistor was contacting the case! Nothing on the unit looks cooked at all, it actually looks pretty fresh. So we carefully bent the wire away from the case, put it back together and reinstalled the tach in the dash and when I'm done with my firewall insulation we'll stick the dash back in and I'll let yall know if I got lucky with this or not. Picture is of a modified tach, but the wire in question is still present where I highlighted it. As a matter of fact, it looks bent in this picture about the same way mine was.

By the way, I just accidentally found this: http://www.dinoplex.org/tachoconversion/index.html but it looks like the final product is meant to work only with electronic ignition systems, which I'm not doing (yet). Has anyone seen any instructions like this on how to convert the tach to solid state that's compatible with the factory ignition? My dad knows electronics and we could put it together with instructions like this. Looks like fun, actually.

@260 z Wow! I'm sure that Z is enjoying the new attention! I'll certainly let you know how it works out whichever path I take with my tach.

@FastWoman Love the black stripe down the inset center of the cam cover! And I'm glad you like my engine bay. The blue is one of my absolute favorite car colors and I'm thrilled I was able to find the paint code to shroud my baby with it!

Having it rebuilt with solid state sounds attractive. Where could I go to get that kind of work done? I'm in the Fresno area, but I wouldn't mind boxing and shipping the tach.

I'm not looking to replace the tach, looking to fix it. Was wondering if anyone has ever had the same problem and fixed the tach itself.

Title says it all. I've got a 72 240Z with a tach that tops out as soon as the key is turned to the on position, start position, and while the engine is running. Only way to stop it is to turn the key off. Pretty sure it's the tach itself and not wiring, etc because I just went through a bit of a situation with my ignition during which I tested and found the entire ignition circuit and every component to be perfectly fine. I'm about to pull the dash to replace the lights and would like to fix the tach, too. Any advice on what to look for and replace when I get the tach out and apart?