One-Family 1972 240Z Restoration (HLS30-93069)

[BoldUlysses]

Got it running again.  It took a LOT of cranking; those 2 inline filters took a while to fill.

I installed the fuel pressure gauge on the rear carb line, like you guys suggested.  Registered 3 psi at idle, which I think is OK.

Now that the float bowls are full, I'm going to try to baseline the fuel level in the jets using the micrometer technique.  Wish me luck, haha.

Side note:  My dad did a great job refinishing the steering wheel.  It took a LOT of elbow grease.

Edited August 25 by BoldUlysses

[Captain Obvious]

1 hour ago, BoldUlysses said:

Got it running again.  It took a LOT of cranking; those 2 inline filters took a while to fill.

Now that the float bowls are full, I'm going to try to baseline the fuel level in the jets using the micrometer technique.

Excellent! Glad it's running!

And I wouldn't bother with trying to use a micrometer. I would just go to the wet-set method with a piece of clear tubing. It's the only way to be sure.

[BoldUlysses]

12 minutes ago, Captain Obvious said:

Excellent! Glad it's running!

And I wouldn't bother with trying to use a micrometer. I would just go to the wet-set method with a piece of clear tubing. It's the only way to be sure.

Me too!

To be clear, when I mentioned the "micrometer technique," I didn't mean simply measuring the gap between the top of the float and the bottom of the lid like I did above, I meant actually measuring the height of the fuel in the jets:

https://www.zcar.com/threads/setting-carb-float-levels.423305/?post_id=2790569&nested_view=1&sortby=oldest#post-2790569

Do you have a link to the wet-set clear tubing method?

[Captain Obvious]

i know there has been previous description of the wet-set method, but I don't have time to hunt now. But here's a couple pics that should make the process clear.

This was done with the bowl off the car, but it can be done just as easily with the carb and bowl in-situ. Clear tube off the nipple at the bottom of the bowl:

I find it helpful to put a sharpie line on the bowl to help with accuracy. You can see the fuel level in the tube right at the 20mm line:

[siteunseen]

14 hours ago, Captain Obvious said:

i know there has been previous description of the wet-set method, but I don't have time to hunt now. But here's a couple pics that should make the process clear.

This was done with the bowl off the car, but it can be done just as easily with the carb and bowl in-situ. Clear tube off the nipple at the bottom of the bowl:

I find it helpful to put a sharpie line on the bowl to help with accuracy. You can see the fuel level in the tube right at the 20mm line:

 

[Yarb]

Historian/Sr. Research Analyst back at work!!

[BoldUlysses]

18 hours ago, Captain Obvious said:

i know there has been previous description of the wet-set method, but I don't have time to hunt now. But here's a couple pics that should make the process clear.

This was done with the bowl off the car, but it can be done just as easily with the carb and bowl in-situ. Clear tube off the nipple at the bottom of the bowl:

I find it helpful to put a sharpie line on the bowl to help with accuracy. You can see the fuel level in the tube right at the 20mm line:

Thanks.  Seems like a pretty straightforward method.  3 questions/remarks, though:

1. I don't want to put a Sharpie line on my carbs, so I'll have to figure out an alternate way.  Blue tape, maybe.
2. It will be a challenge to get a straight-on view of the float bowls when they're installed on the car.  Will have to figure that out.
3. Do you account for the different float levels needed for the front & rear carbs?

I tried the micrometer method, but it's basically impossible to see the fuel level relative to the top of the jet in order to set it properly.

Also, the fuel level is supposed to be .426" from the top of the bridge, but that's right about where the jet bottoms out, making adjustment in that range a challenge.

Will keep trying.

Edited August 25 by BoldUlysses

[Captain Obvious]

4 hours ago, BoldUlysses said:

I tried the micrometer method, but it's basically impossible to see the fuel level relative to the top of the jet in order to set it properly.

Exactly. I find the wet-set to be much easier and way more accurate. So for the wet-set - If you're not comfortable with a sharpie line on the bowl, then sure... Use a piece of tape. Sharpie does wipe right off with carb cleaner though. 

As for getting a straight on-view, maybe use a mirror? I may be in the minority, but I don't think the measurement down to the fraction of a mm has that much of an impact.

Which leads me to the last question about accounting for the different float levels needed for the front & rear carbs? I guess, if they're already different and close, I'd let them alone, but I think 20mm  +/- 2mm will work. The 70-71 carbs all used 20mm.  It wasn't until 72 that they started messing around with the levels like that. To me, it seems like some Nissan engineer was looking to make a name for himself and thought it would be a good idea to dive into the minutia due to engine tilt.

"Boy... My 70 and 71 just always seems to run different between the front and rear carbs. I bet it's because of engine tilt."   Said no-one ever.   

[Namerow]

If only the SU's designer had included an external adjustment screw for setting the float level. 

[BoldUlysses]

23 hours ago, Captain Obvious said:

Which leads me to the last question about accounting for the different float levels needed for the front & rear carbs? I guess, if they're already different and close, I'd let them alone, but I think 20mm  +/- 2mm will work. The 70-71 carbs all used 20mm.  It wasn't until 72 that they started messing around with the levels like that. To me, it seems like some Nissan engineer was looking to make a name for himself and thought it would be a good idea to dive into the minutia due to engine tilt.

"Boy... My 70 and 71 just always seems to run different between the front and rear carbs. I bet it's because of engine tilt."   Said no-one ever.   

Actually there are quite a few threads discussing disparities between the front & rear bowls leading to running issues...

I decided to go with 21mm for the front and 19mm for the rear.

Took a couple cranks; I was reasonably close.

Final float position:

I think I have 1 washer under the Grose jet; I could have probably removed it, but I don't like the idea of the jet grinding its way into the underside of the float bowl lid without a washer, so on the balance I prefer to just position the float.  Final gaps to the underside of the lid:

Front: .240"
Rear: .215"

2.5 turns down on the jets; it cranked & started fine, and I gave it a basic tune.  As evidence that the float level difference was accurate:  My first Uni-Syn readings from both carbs were identical; that's never happened before.  Drove it around the neighborhood and got it warmed up, and settled it down to a nice 700 rpm idle.

A little more tinkering, and I decided to drive it around the neighborhood again.  Everything was going fine until...

It died.  Again.  Fortunately I was able to coast back into the driveway and pull it into the garage on the starter.

Both filters:  Full.  It can't be gunk in the tank.  It always happens about 10-15 minutes into the running session.  Surely it's not something like vapor lock in the hardlines above the manifold?  Could it be ignition-related?  Bad coil overheating and then shutting down?  I'm so frustrated.  I don't know what else to do except to keep looking for blockages; going to pull off the hardlines & clean them out tomorrow.

[Captain Obvious]

Well the carb work sounds like it turned out well. But the dying thing is certainly a pain.

So what kind of ignition system are you running? Normal points and coil kinda stuff?

[BoldUlysses]

1 hour ago, Captain Obvious said:

Well the carb work sounds like it turned out well. But the dying thing is certainly a pain.

So what kind of ignition system are you running? Normal points and coil kinda stuff?

Yeah it really sucks to not be able to actually drive anywhere.  Last time it happened the car died and coasted to a stop around a blind corner of a busy two-lane road.  A couple of local boys stopped and were going to push me into the subdivision, but fortunately, I was able to get it to catch just enough to make it there, so they didn't have to.  Let it sit for 4-5 minutes, then I got it to start and (barely) run again, enough to make it home.  Very embarrassing.  Sigh.

OEM coil, Pertronix points replacement, wired up in the dist.  Maybe it's ignition-related?  Found this here:

 

 

Edited August 27 by BoldUlysses