3 years of sitting... what to do first?

[EverRude]

Ok figured out the problem. Turns out after a bit of research I realized I need to set the float levels hanging correctly. Flipping it upside down and setting them was essentially shutting off the fuel completely. Used a 15mm diameter bolt and held the float assembly so the float hung properly. The set the float using the bolt as a go-no-go guage. I also use a pice of tube and blew into the fuel inlet and confirmed fuel shut off just when the float contacted the bolt.

After that I reinstalled everything and she fired right up.

I managed to set the idle down some to just below 1000 but can't seem to get lower without the engine dying. I set the air balance at that rpm using the unisyn. Then started tweaking the nozzle. I had it initially set at 2.5 turns out. Minor tweaking seems to have no noticeable effect. However making several turns one way or the other does. Raising the cylnder slightly by hand on front carb killed the engine. Didn't try the back yet. Cause now it won't idle without the choke on.

There was also a hesitation when I accelerated. If I did it to quickly it wanted to die. Sometimes did die.

So looks like I have some more tweaking to do. The off idle hesitation. The high RPM. And the current refusal to idle without choke.

BTW Bruce Palmer called me out of the blue when he read my previous post to tell me about the upside down float issue. I had it sorted by then but it was very great of him to call and try to keep me from taking a sledge to my carbs. That is some serious customer service and I appreciate it very much Bruce. Thanks again.

[EverRude]

Just thinking, was 15mm too much? Or too little rather. Meaning is my fuel level too low in the bowl and now it won't idle properly because of it. Would also explain the off idle hesitation. But not sure it would explain the high rpm.

Or maybe my butterfly is open too much at idle. Requiring more fuel at the nozzle (too many turns). This would also explain the off idle hesitation if I am thinking correctly. The burst of fuel needed to come off idle (vacuum drop) should come from the nozzle pool. But that is being used up faster than it can be maintained due to the excessive idle speed caused by the butterfly being too open.

I believe I understand this carb fairly well. The process it using to provide fuel and air at the correct rates. The trouble is decided what part needs tweaking to supply it in the right ratios.

Think it's the butterfly. Too much air right now. Gonna go test. I'll post back the results

[steve91tt]

The butterflies are adjusted by the unisyn. If you have them open too much but sync'ed then you should idle high but not have hesitation issues.

Just an idea...you may have a vacuum leak. Now that it idles, have you tried a shot of carb cleaner directed around the intake gasket area and at the throttle shafts. If the idle changes with a squirt of carb cleaner then you have a leak. If it's at the gasket...easy fix. If it's at the throttle shaft...new carb(s).

[EverRude]

Ok it's official. The off idle hesitation is caused by leaky throttle shafts on both carbs.

Here's the story.

I got rpm down a bit more but it was a rough idle there. So I kept it at 1000 for tuning purposes. Used unisyn and got equal flow to both carbs. I then used fast idle screw to set rpm and used balacing screw to equalize both carbs at 3000 rpm. She still would hesitate off idle. But I thought, what the heck. Quick test drive. Didn't even make it off the pad before she died trying to take off under load. Start it back up and tried to simply give it more gas before releasing clutch. Died again. OK. More gas or give up and keep tuning? I gave up put it in reverse and proceeded to attempt to back up 5 times before I finally had her back on her spot.

Started her back up and let her idle. Yep balance good. Running rich though. Practically choking on the gas fumes.

I figured she was running well enough now that perhaps I could use some silicone spray to test for vacuum leaks. Sprayed throttle shafts first. RPM went up everytime I sprayed shaft on both carbs. Both side of both carbs. So it's pulling air from shaft on both sides of each carb. Great. Just great. My guess is there are more leaks. I'll find those and fix them, but the throttle shaft leaks I can't fix.

Guess it's a good thing wife had already approved funding for some new carbs.

Hey Bruce. We need to talk again

[EverRude]

The butterflies are adjusted by the unisyn. If you have them open too much but sync'ed then you should idle high but not have hesitation issues.

Just an idea...you may have a vacuum leak. Now that it idles, have you tried a shot of carb cleaner directed around the intake gasket area and at the throttle shafts. If the idle changes with a squirt of carb cleaner then you have a leak. If it's at the gasket...easy fix. If it's at the throttle shaft...new carb(s).

Thanks bro. Wish I had waited a few more minutes for a response. Would have saved me 30 minutes of tweaking and frustration. Oh well. You guess was right. Time for new carbs.

[EverRude]

There is a 73 240z close by with complete interior but its automatic. Rusted hull but complete with unmolested harness. 400 worth it ya think? Carbs are weber dgv so useless to me. Auto trans useless. Should I bother? I have space to store so not an issue there.

[Bonzi Lon]

I would jump on it for that price. There are lots of parts you can use or sell, the carbs right off the bat to make up for the car, somebody wants them. Lots of spare parts that you don't know you need right now. Always nice to have a parts car. If you do get it, before leaving ask if there are any more parts, I got a 73 FSM that way.

Bonzi Lon

[EverRude]

Actually the $400 was minus carbs. Carbs and intake added another $250. Not worth it by a long shot. I decided to leave that car alone. However I am possibly getting the interior parts I need from it. There's a local junkyard with a 72 240z and I got a ton of parts from it I needed. Thinking about going back for dented bumbers and good looking radiator and shroud.

OMW in the morning to pickup a rebuilt 260z motor and 5 speed trans from a hybridz guy that swapped it out with a v6 he installed for more fuel economy and power. He hung onto the engine tranny assembly for 3 years thinking he might get another Z to use it in and is finally selling to clear space in his garage. He swears the SU (3 screw) were perfect and he had recently rebuilt them with a ztherapy rebuild kit. For $450 for engine tranny and those SU's I'm willing to risk it.

[EverRude]

She's running fairly well now.

Here's the scoop. Picked up the 2.6 moto,r 5 speed tranny, and 3 screw carb assembly yesterday. After 13 hours of traveling I didn't feel like working on car so waited till today to start swapping. I am doubting the rebuilt motor at this point. But it was just icing on the cake. Cared more about carbs and tranny.

Anyways decided to just try carbs first. So I installed them without doing anything. Shoulda checked float hieght but I'll be honest I suspected they were just as bad as my old ones after I got them removed from motor. Alot of play in shaft. I was sure they would leak. They didn't. Had to do floats at that point. Then balanced them. She idles at 800 and both carbs balanced easily.

Unfortunately it didn't remove all the off idle hesitation completely but it certainly helped. A quick test drive revealed she still struggled under load a good bit but it was better. Stalled easily on take off. So I searched forum for answers to the stalling and hesitation.

I found out the coil and condenser could cause those issues. So I replaced them both from parts from my 70 Mustang motor. Hesitation gone. Load stalling gone. She pulls easily without requiring tons of gas. Runs fairly smoothly in fact and the sputtering I had heard at idle was gone. I drove her around my small backyard in second gear at like 5 miles and hours in circles and she did it smoothly. Before she would stalled and died trying that.

So all in all I'm happy. BTW 3 screw carbs suck. There's a boss on side of carb body that prevents the float bowl lid from coming off and being installed with the float attached. WTH is with that? The 4 screws have no such boss and the float lids lift straight up without a need to remove floats first.

Anyways while I test drove her I noticed the clunking I had heard before. Now I have all 6 ujoints but I only installed the driveshaft joints before and not the half shafts. I decided to go ahead and do half shafts now that she runs nicely. Unfortunately those are more corroded and caked with grease than the driveshaft so I cleaned then and soaked them with Liquid Wrench to finish tommorrow rather than fight them today.

Again I think I did good. Might still get those ztherapy carbs just to get my 4 screws back. But I believe I may just be driving her to work someday this week. Yay.

[Bonzi Lon]

[quote=EverRude;360561

So all in all I'm happy. BTW 3 screw carbs suck. There's a boss on side of carb body that prevents the float bowl lid from coming off and being installed with the float attached. WTH is with that? The 4 screws have no such boss and the float lids lift straight up without a need to remove floats first.

Was it only on the rear carb? I had the same problem, could not get that lid off no mater which way I tried. Solved that problem by sawing off the offending ear. It appears the redesign for the 3 screw included using the same casting for both front & rear carbs, as this boss is on the other side for the choke bracket attachment.

Tried to put photo in but couldn't, not like before.

Bonzi Lon

[EverRude]

It was both carbs. I may remove the bosses when I perform engine swap in a month or so.

Today all I managed to do was get the half shaft ujoints replaced. They were a nightmare. They were aftermarket greasable ujoints installed already. Whoever installed them managed to mangle the shaft holes enough with a hammer that I was forced to use a dremel with a small cutting blade to remove the dented metal preventing the joints from separating. Not a fun job. 5 hours of work to replace 4 ujoints. The main drive shaft took maybe 45 min and that was spending some time cleaning the shaft.

So tommorrow, if weather permits, I'll install half shafts. Hopefully have enough time to sort out why the fuel guage doesn't work and then repair the blinkers and brakelights to normal operation. Really hope to drive her to work sometime this week. Guys on my crew getting frustrated hearing about my new toy but not seeing it.

But however frustrating it was I did make progress today and that's all that matters IMO.

Edited April 12, 2011 by EverRude

[EverRude]

Halfshafts installed yesterday. Didn't have time to do much else but decided to take her for a spin. She sputtered and lurched whenever I would take off. Severely. Once I was leveled out all was good again. But anytime I turned sharply and braked hard I was treated to some severe lurching. Really upset me. I took her home and parked her. Was too late to troubleshoot.

So today I decided to sort out that issue. There were several issues I needed to sort out but doubtful they had caused the issue. The SU damper fluid was low. The cylinders would move atleast a quarter of an inch without any damping effect. I understand that could cause a fluttering and mess with venturi and fuel flow. Possible cause of the lurching but doubtful. Still I used a syringe and pulled the existing fluid out as best I could then used 20w 3in1 oil.

I decided to try checking timing with a vacuum guage. If you've never done it, it's kinda cool. It does work better on V8's though. Put a vacuum guage on a balancing tube port and adjust timing to get the best vacuum possible with the least amount of needle bounce. The bounce is caused by the valves opening and closing. The smallest ammount of bounce will give you a nice smooth running motor. I set this with the disto vacuum disconnected btw. But I had to retard timing slightly because it was too much advance and cause a hard start. Trouble is without a timing light and not really knowing what disto I have (obviously a replacment) I don't know my total timing. Anyways I was hoping this would help a bit with the hesitation.

Advancing the timing caused my idle to change. Jumped atleast 400 rpm. So I rebalanced carbs using Unisyn. Got idle back down to around 900 with a good balance between carbs.

That's when she died. Seriously. Just quit. So I tried to start her back up. Nothing. She was plenty warm but I hit choke anyways. Nothing. WTF I asked myself. Several times. Then I noticed the fuel pump was louder. Hmmm. So I checked fuel pressure guage. Zero. Crap I say, using other words. Shut off pump and disconnected fuel pump outlet hose. Dry. Dang. So I disconnected inlet hose. Nada. Crap again. Then it hit me. Outta gas. No way. Seriously? Sonofa...

So I figured out the lurching problem. Thinking back it was happening on sharp turns and hard braking and launching. The little fuel in the tank was sloshing away from the pickup tube and causing the pump to loose fuel causing the car to lurch as the fuel was shut off sporadically.

Moral of the story? Fix the fuel guage.