rcv

Welcome to the “why did I have to do this” club! We’re inducting new members every year it seems.

How’s it been holding up these past 11 years? I was thinking of getting one as well.

I never figured out the root cause, but putting an extra 4mm of washers under the ball pivot worked great. I’ve been driving the car plenty like that, and haven’t had any issues… well no issues with the clutch at least 😀

Nice, those mostly line up with the measurements in my image (repasted below for reference). The only one I can't really match up is the bottom-right in your image with the 46.84mm ear to TO measurement. Do you happen to know what vehicles each of these originally came out of? It would be helpful to label them if so. Also, one more measurement you could take would be from the top of the throwout bearing to the top of the collar. I'm pretty sure this is a functionally useless measurement, but it's what's provided in all of the other collar images I've seen (e.g. https://www.classiczcars.com/forums/topic/64212-clutch-fork-throw/?do=findComment&comment=602080&_rid=33357) and would help match your measurements to other images. Thanks for doing the legwork here, I'm sure it will save someone a lot of headache down the road.

Did you happen to measure any height difference between your old pressure plate and your new one? I had tried the same simple solution, but the old plate had the same issue as the new. I asked the PO but he didn't remember any clutch issues. The car hadn't been driven in about 15 years so he wasn't too sure though.

@123ignitionusa I just stumbled on this old thread after making a dupe. I had some issues getting my tach to work in my 11/70 240Z but resolved it with the help of some friendly forum members. The solution is here - my beautiful drawing is public domain so feel free to reprint it 🙂 While I have your attention, it would be extremely cool if there was a library of user contributed centrifugal and MAP curves that beginners like me could reference - especially if they were listed along with engine specs (e.g. carbs, cam, exhaust setup etc). Also, the initial timing degrees. I'll bet if you put out the call here and on hybridz you could get some forum members to contribute.

Wahoo it works! Thanks for the help @Firepower For anyone else who stumbles n this thread, here’s how I wired it up. I made a “Y” connector to connect the following wires: - Green/White - Red wire that goes to the distributor - Black/White wire that gets 12V when your key is switched to “on”. The other black/white wire (which does not read 12V when the key is in the “on” position) goes to the positive terminal of the coil.

If you have an example of each collar on hand, then you should measure the distance from the leading edge of the TO bearing to the top of the ears. It’s the red dimension in my image, but I derived my numbers by counting pixels in the photos. If you can get the actual measurements with calipers and annotate them in a consolidated image, then you will be the only person in the known universe to have done so and you should make that image a sticky.

I have all of the measurements for the various collars (using the important dimensions) in a handy diagram here:

Thanks Richard - I believe I tried that, but had no luck. I'll give it a shot later and see if I can figure out what I screwed up. When you say you jumpered both wires, you mean the Black/White wire, and the Green/White wire right? Also, thanks for the "240Z 123 Ignition Tune+ Install" video you did you Youtube, it was my main reference when I installed mine and it was a huge help.

@Sailor Bob what's the manufacture date of your car? I'm guessing this is an oddball early model problem.

What's the latest on getting fuel pumps rebuilt anyway? I went through 3 mechanicals (the OEM and two cheap knockoffs) before I finally caved and installed a little K&N electric pump near the tank. I can hear the clicking sound of that electric pump in my dreams now so I really would like to go back to a mechanical unit at some point. Last I heard people were trying to figure out how to scavenge the one-way valves from some new units to put into the body of the old units to make some kind of best-of-both-worlds-frankensteins-pump. Anyway, let me know if you find a good source for reliable mechanical pumps - I'm interested.

Sure thing, let me know how it works out. I'm still academically interested in what the root cause is here but so far my curiosity hasn't been as strong as my desire to drive my car.

Yeah that's a good idea. You might need to put a very small resistor in parallel with the potentiometer, otherwise the current through the pot will be super low and subject to whatever the impedance is in just the wiring. The goal would be to make the current flowing through the pot+tach the same as it used to be, but to also get some extra juice by pulling in extra current through the low-ohm resistor that's in parallel. I'm not sure when I'll have time to source the parts and try this, but it sounds like good experiment.

Yeah, I think that's my plan. I did some more searching, and came across this great diagram by @240260280z in this thread: I think that basically explains it - I removed my ballast resistor when I installed the new Bosch coil which I think was the wrong move. I'm guessing the tach is acting like a voltage divider along with the ballast resistor, and removing that resistor screws up the formula. I measured that Bosch coil this morning, and it reads 1.5Ohm on my meter even though it's spec'd at 1.8. I'm just going to replace it with the old 1.5 Ohm Flamethrower coil and the ballast resistor that I had in there before. Here's hoping I didn't fry the loop in my tach when I was playing around.

Sorry to hear you're having the same problem @Sailor Bob, but at least neither one of us is crazy (or we both are). I had to re-read the thread to remember, but it seems to me like the issue isn't actually the pressure plate or the collar, as I was getting the proper 92mm stackup. The problem seemed to be that that my pivot ball was too short. I'm not sure how it's possible, as @240dkw's pivot measures the same on the bench as mine but a few mm longer when installed. Some kind of local space-time distortion is the best I can figure (or measurement error on my part, whichever makes more sense). Adding an extra 4mm of washers under that pivot ball brought the distance from the tip of the ball to the front face of my bellhousing to 105mm (@240dkw's measured 103mm). The transmission is now installed and I've been driving the car every chance I get. The clutch feels perfect. I'm hopeful you can solve the mystery, but if you get tired I recommend just slapping two 2mm washers under that pivot and see if that fixes it for you.

@duffymahoney Yeah, that was my hope but it doesn't seem to be sensing anything now. I figure that wires ②, ⑤, ⑥, and ⑦ must have something to do with the tach and I just haven't hooked them up correctly. Would you mind snapping a picture of the wires you have hooked up to your ignition coil? What did you do with that little black wire that was hooked up to the capacitor hanging off the old distributor (mine is electrical taped along side the temperature probe wire)? In better news, I went for the first real drive this morning with the new distributor and the engine feels really great. I'm not sure if it's going to help my fuel economy, but my smiles/gallon has definitely increased.

Hey Everyone, I just replaced the stock distributor in my 11/70 240Z with a new 123Ignition unit along with a new Bosch coil. The car now runs great, but the tachometer no longer works. When the engine first turns on the tach jumps up a little bit, but then slams back down to 0 and stays there. Anyone have any advice on what I screwed up? Here's how things are hooked up currently (see image below for my wire numbering): [Black] The black wire going to the 123Ignition unit is connected to the coil negative [Black] There's another black mystery wire that was hooked up to the old coil negative, so I hooked it up to the same place on the new one [Red] The red wire to the 123Ignition unit is connected to the coil positive [Black/White] The green/white wire that used to connect "back" side of the resistor is now connected to coil positive [Black/White] Another mystery black/white wire that used to be connected to the old coil positive so I connected it to the same place on the new one [Green/White] This wire used to connect to the "front" side of the resistor - it's currently disconnected [Black] This wire used to connect to the little spade terminal on the old distributor, which then connected to the little capacitor hanging off the side. There's no such terminal on the 123Ignition unit, so this is also currently disconnected. [Blue] (not shown) The ground wire to the 123Ignition is connected to the chassis Someone in another forum had mentioned connecting wires 5 and 6 together, which I tried but no joy. By the way @Captain Obvious your spring has served very well up to now - let me know if you want it back and I'll be happy to put it in the mail!

Did you get the measurements you need? I’ve got an 11/70 and I’m happy to break out the tape measure this weekend if you’re still in need.

Yeah, I'm really hoping it's just the exhaust hitting some resonant frequency and banging into something occasionally. I've got a big piece of 1.5" tube that I've been putting to my ear and trying to hunt down the sound - I'm sure my neighbors think I'm a crazy person. I haven't been able to pinpoint it yet, but it's comforting to not hear you say "that sounds like pinging and your engine is about to blow up." I'm still waiting for the DMV title transfer to go through, but I've been on a few questionably legal burns up and down my street and it feels great. It feels like there's plenty of power, and there's no hesitation as far as I can tell. I'm hoping I'll have legit plates and registration in a few weeks, and I'm really looking forward to working up to a drive down Mulholland here in LA. I'm running the "SU Carburetor Oil" from MSA right now - it's advertised as "the best dampening fluid for SU carburetors" but I have no idea what it actually is. Probably just plain 20W oil.

Just a quick update - I bought some new SM needles from Joe Curto over at British Superior and dropped them in. The car immediately runs much better. I think I've got it tuned just about right - the ColorTune is showing a nice blue color, and slightly raising the piston by pressing on the little maintenance pin makes the revs go slightly up and then back down. I'm occasionally hearing a "rattling" sound from the engine now. At first I thought it was just all of the tools/WD-40/junk I had on the fenders, but I cleaned that all off and I still occasionally hear it. I've tried to track down where it's coming from, but I haven't found any loose bolts or anything else that looks like culprit. I've heard that detonation can sound like "a ball rattling around an empty spray paint can" so now I'm paranoid that I'm getting detonation. Can one of you experts give this a listen towards the end and let me know if I should be worried or not?

Yeah, but I really just eyeballed them separately. I'm mostly concerned about getting the engine to idle correctly right now as an experiment, so I figured that the drop rates wouldn't be too big of an issue until I start fluctuating the throttle. I'm keeping things organized on my bench so that it will be easy to re-match things once I feel like I have an idea of what's going on. Absolutely - I texted Jeff already but I'm planning on giving him a call in the next day or so when I get a moment. He advertises a "1 year warranty" and I bought the carbs last October, but I'm hoping he'll be reasonable about it. Let me know if you decide to incorporate BruceTech - I may be in the market soon.

Just the pistons. I want super rigorous about testing their drop rates like the ZTherapy dvd recommends, but they seemed roughly ok.

Good idea. They don't have them listed on their site, but I'll give them a call and see.

Well I may have celebrated a little prematurely. I had only color tuned the rear carb before my last post. I just went out and tried tuning the front one and it’s still rich, even with the mixture cranked all the way in.