76 TLC Aisin Carb help

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Chungas Revenge

Chungas Revenge

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Figured I'd kick this over the fence this AM.

Having trouble dialing in an OE 76 Aisin Carb. De-smogged original 2f. Looks like its loading up. Double checked for vacuum leaks. New solenoid, fires up at full choke, runs ragged for a minute or so, half choke smooths out, 1/8 choke purrs. Dies out when I close the choke. Running on the partial choke (1/8) runs fine. Gave it a test run up a steady winding trail. Couple miles into it the engine fluttered and died. Let the bowl drain for a few minutes, fired up and I drove it back to the barn. Hard start the next time I tried to fire it up. Again, same scenario as before...

Mixture issue?

IMG_2351.webp


IMG_2373.webp
 
I'm confused by the pictures... is your carb leaking or is this the result of "draining" it?
When you say close the choke, does that mean full choke or no choke?
 
If it runs better with the choke on, then it sounds like a lack of idle fuel / manifold vacuum problem. It is hard to tell which, but you can tell if it is getting some idle fuel by disconnecting the solenoid wire while idling. If it stalls, it is getting some idle fuel.

The fuel puddle on the carb base is because you have drops of fuel dribbling out of the main nozzle onto the primary butterfly because you are compensating for the lack of idle fuel / vacuum.
 
I think you have more than one problem. Idle circuit is just part of the problem. WAG float is not set properly either.

Best

Mark

www.marksoffroad.net
 
Pin_Head said:
disconnecting the solenoid wire while idling. If it stalls, it is getting some idle fuel.
Click to expand...
Thanks Pin, I'll give that a go.
 
@Pin_Head
@65swb45

I'm headed back to work later today. My LC is tucked away for safekeeping. But, I should be able to test the solenoid theory early this week. Should I leave the breather assembly on or off when checking the solenoid? I've checked the vacuum, I have zero surge on the RPM when I cover the Carb and the motor dies straight away.

Thanks for the lifeline!
 
Pin_Head said:
It does't matter. Just don't have the choke on and make sure that the RPM is idle speed: 650-700. If you have the air cleaner off, you can watch the fuel dribbling out of the main nozzle
Click to expand...
...if the idle circuit is NOT working properly. Marv Spector said it best: when it's working properly, it looks like FM (f'ing magic) You shouldn't see any gas.
 
@65swb45
@Pin_Head

I only had a few minutes to "fiddle" with this today. Cranked up and let it warm to operating temp. Brought it down to 600-700 rpm. Unplugged the circuit.... No dripping fuel out of the 1st or 2nd main nozzle. no change. Engine continued to idle. After 4-5 minutes it sputtered and died. I have not checked the solenoid valve. I'll pull it this week and check for serviceability. I'm about 8mm on the throttle positioner, my idle mixture was about 2 turns from full closed, and I am about 1mm on the fast idle.

Thanks again.
 
It would be helpful to know what your vacuum reading was at that point.

If it ran without dribbling at that rpm, you can rule the solenoid out.

What is the fuel level when it sputters out?
 
1/2 on the glass while at idle. I'll check in the next day or so IOT determine the fuel level when it takes a nose dive. 2nd pic is not a good one, you can't see past the air horns. I'll try and take a better pic or video next attempt. I tried closing off the carb and it died straight away without any surge in the rpm before it quit running.

@65swb45

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I was having a similar problem that turned out to be the carb throttle plate catching on the gasket and holding it barely open. Once I trimmed the gasket to fit the carb and manifold the idle circuit worked properly (car stalled when I unplugged the idle solenoid). Just a thought. Pin head and Mark are way smarter than me on these things!
 
Very,very similar symptoms to my 77 after I found trash in the fuel tank(not related to your prob, I don't think)----but, the part that might be is after the issue I had with the tank, I could run several miles at normal rpm and vac--then the vac would slowly degrade until I could not keep the engine running(like at a stop light) unless giving it gas -up to 1000 rpm. Finally got frustrated and stomped the accel in 3rd gear--right to the floor--maybe 4-5 times-- next light I come to, the engine decides to idle like it is supposed to--20 inches vac, rpm at 700--so what the heck happened?? (I'm guessing a running Oakie rebuild)--musta blown something loose in the carb that cleaned up an idle circuit--that was 2 weeks ago--still idling and running normal so far.
I do have a Weber carb, but the operating principles would seem the same---there may be something in the idle circuit causing your issue
 
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