240z still not starting

[Stanley]

MSA (click their logo on this site) sells the "synchrotester" (the one used in the ZT video) for about $30 and the synchrometer for about $50. I like the synchrometer cause it has numbers you can record, but it's plastic so it could break I guess if you drop it on concrete. Both do the job. The tuneup in the FSM is as easy to follow as any but it leaves out the rich-lean check with the push pins under the carb (at least my 72 S-30 engine manual leaves it out). Tuning by ear is for experts. The chart in FSM shows different mix settings for average temperatures, so for best performance in a location that's hot in summer and cold in winter, carb mix tuning is twice a year. A stopwatch and notebook are also handy for cheapo performance tuning. NO TUNE - NO LIFE.

[ninjazombiemaster]

Okay. I was just hoping I could get it locally so I can skip on ship times. Also, what thickness clear tubing should I use to test the float level? No guide I've seen so far really specifies.

I worked with it some more, and got it running a little better yet. The lowest I could get it to idle and stay alive as its supposed to in the push-pin test was over 1500 RPMs. If I richened it any more, my exhaust backfire worsened. If I increased the airflow, the RPMs because too high. I just can't get them at a low idle and pass the push pin test on the front carb. But It's better than the day before. Just how much suction should they have at idle? Something isn't right..

Right now I've got it running a little fast at 1000 RPMs, and it fails the pin test, but it got me to work.

[Captain Obvious]

what thickness clear tubing should I use to test the float level? No guide I've seen so far really specifies.

You said thickness, but I'm assuming you meant inside diameter?

If that's the case, then you need something close to 3/16 ID. It's not a critical fit since you're not going to be running the car with it installed. Just something snug enough that it doesn't leak or slip off accidentally while you are verifying the bowl levels.

Clear PVC would be a good choice for short term gasoline contact and you can probably find something suitable in the lawnmower repair section of your local home and garden supply store.

[ninjazombiemaster]

You said thickness, but I'm assuming you meant inside diameter?

If that's the case, then you need something close to 3/16 ID. It's not a critical fit since you're not going to be running the car with it installed. Just something snug enough that it doesn't leak or slip off accidentally while you are verifying the bowl levels.

Clear PVC would be a good choice for short term gasoline contact and you can probably find something suitable in the lawnmower repair section of your local home and garden supply store.

Thanks cap'n thats what I was looking for. Also, good news. I figured before I got spendy, I'd double check the my random car parts box and look what I found!

Looks like the PO was nice enough to have given me his old unisynch and I never noticed. I also found some other well needed yet forgotten goodies like new weatherstripping.

Bad, yet unrelated news is my Retrosound radio is definitely toast. Probably out of warranty, too. Guess I'll have to just listen to good old engine noise until I can fix it or save up 3 Bennys.

[Captain Obvious]

Figured as much. So after you verify that your float bowl level is correct and move to tuning with the engine running, here's an extensive collection of SU tuning information. It's from one of the stickys at ZCAR.com, and you should read, read, and read:

carb tuning; can't find Norm's procedure - ZCAR.COM

If you can't tune your SU's after studying all the info in the above thread, then you should just take it to someone else. And yeah, that Unisynch should come in handy.

[olzed]

I have a synchrotester, and ditched it in favour of a piece of half inch plastic hose to my ear. You would be surprised how accurate it is. Hearing the same vacuum pull is not hard.

[LeonV]

The Uni-syn is junk compared to the Weber SK tool. I got mine online for about $35.

[ninjazombiemaster]

Its just an edelbrock I got from the PO. Turns out I had got it spot on by ear. Its running better everyday, so at least I'm making progress. I pulled my plugs, and the front 3 seemed rich, and the rear was pretty good. I'll post pictures in a bit. It also seems like once the engine is warm, the only backfire occurs if I open the throttle quickly, or flutter it. Similar, if not a lean pop. It happens out both carbs at once, the fuel is not ignited. But its been in the single digits. After fire comes into play when I richen either carb any to help settle the pop. Leaning it immediately stops it. Perhaps they really are lean, but my plugs arent burning hot enough to richen it?

[ninjazombiemaster]

Plug #2 - looking rich : Plug # 4 - looking pretty.

These are Autolite 63s I believe. The store only had 2 NGKs, so I had to settle. Gap is identical to my old plugs, which worked well. Dunno if its spec though.

I've got the day off tomorrow, so I should hopefully be able to hit the hardware store and grab some tubing to check my float levels. I recorded a video of the behavior, of the carbs when the engine is warm. I'll edit and post it when I get home from work, so you guys can see whats going on. Like I said before, It happens most when the throttle opens suddenly, sometimes when I start the car (warm) and especially when its cold. Seems like a lean pop, and unburnt fuel puffs out both carbs. But if I enrich the mix, I get little after-fire pops (no visible flame), and thick, white exhaust.

[LeonV]

Do you have oil in the SU domes? Check for vac leaks?

[ninjazombiemaster]

Yeah. Ive got 5-20 weight in it. Couldnt find a better option locally. It seems like it doesnt really kick in soon enough, like the lowest bit isnt dampened, causing a lean mix. Im pretty sure I got plenty in there, they are pretty hard to move. I really am wondering about vaccuum leaks but all thats changed is the carbs, and all the bolts are tight, I checked that yesterday. Being that nothing changed but cleaning the carbs, changing the starter motor, and plugs. I dont see how a vaccuum leak wouldve developed, but I'll look for one

[Captain Obvious]

Post a couple good pics of the engine bay. Maybe there's something related to the conversion from flat top to round top that might show up in the pics? Are you still running the 73 balance tube?

Have you talked to ZT about your carbs? From what I've seen, they are more than happy to provide assistance to get thier stuff running properly.