Nikki issues!
 

So last night I drove my FB for the first time in over a year. That's the good news. The bad news is that I can't get it to run off choke.

Good:
Rebuilt motor (good compression, timing is set properly)
Floats are set properly
Rebuilt carb

Bad:
-Motor builder either used warped housings or pinched the coolant seals, so I have some Bars heavy duty copper-based sealer and AlumaSeal in the radiator. Pisses coolant out of the outside of the housings, not into the combustion chambers.

-Accelerator pump won't fill with fuel.
---Check ball and weight are in their proper place, rear fuel bowl has fuel at proper level, and the passage is clear

-Motor won't run below 2000rpm.
---Sprayed around carb with ether and didn't see any change in engine speed. No vacuum leaks.


-Motor won't run off of choke
---I release the choke after the motor has warmed up, and if it's not under load it'll go from 4k to 6.5k rpm, and then slowly "idle down" to 2k rpm, and then die.
---I release the choke after the motor has warmed up, under load, and press the accelerator. I can hear the primaries opening, but the motor won't make any power. It bogs, and then starts backfiring.
---If the choke is held closed it'll make a usable, but not adequate, amount of power to 4k, and then it falls on its face. I know my secondaries aren't actuating, but the lack of power below 4k, and the fact that it will run OK on choke, bothers me.

I worked through the idle tuning process on Sterling's site with no luck. Any suggestions? I know a lot of my issues are coming from my accelerator pump not filling with fuel.

Thanks in advance

-Jim

Bump.

Is your phenolic spacer upside down? That happened to me once and it caused all sorts of oddball problems. If yours isnt broken you should be able to read the 1491 (or whatever the number is) on the heatshield part of it.

That's a good thought there Ian... :)




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How's the fuel level in the sight glasses?

Phenolic spacer? That's under the carb, yes?

Halfway up the sight glasses.

Also, I was thinking: The jets in the bowls. Two numbers are stamped on them, depending on whether they're primary or secondary. There should be one of each number in each fuel bowl, correct?

Correct on both questions...

I have it correct side up. It will hold fuel if it leaks out.

To the top!

Bump

To the top.

If the acc pump wont fill with fuel, and your sight glasses show fuel, the carb has to come off and ALL the ports cleaned. No other way.

Agreed.

The AP pump takes fuel from the bowl directly in behind it. There is a small passage at the bottom of the bowl. Are there ANY signs of fuel leakage from the AP pump housing?

I removed the carb, soaked everything in chem dip, blew out all the passages, and passed a piece of piano wire through the passage between the rear fuel bowl and the accelerator pump (AP diaphragm and cover were off...). The passage is clear. NO fuel is coming out (even with the AP cover off...). All new seals were put into the carb when i rebuilt it.

Check ball and weight are in the correct locations and orientation (check ball went in first...weight on top of it...)

Ya since it sat I would check the pilot circuit. Not sure if they come out of the carb easy. I have a couple spare Nikkis. I have the same issue with my 79 that has sat for probably 8 of the last 10 years.

Pilot circuit?

ok this might be a some what dumb answer but it worked pretty good for me when i started my car after it sat for 3years. when i first started it it didnt run right at all n did not want to idle at all. i smiply put seafoam in the gas tank alnog with 2gallons of 93. (gas tank was completly empty) it would idle after that but still did not run right. i found that the shutter valve was stuck open. i got it working again now car runs fine. (other then i need new plugs n wires) but i no longer have carb problems. yours sounds more sirius tho but i thought i would try to help.

Running an early FB/SA intake mani w/o any of the emissions crap. I *May* swap for my '85 manifold to see if that helps, but that doesn't explain why my AP won't fill with fuel.

Bump.

You keep saying "check ball and weight."

There are 2 check balls, and 2 weights, in the accel pump circuit:

One ball and one (thin) weight under a jetted plug near the pump itself.

One ball and (fat) weight under the accel nozzle itself, center of the primary barrels.

If the ball and weight under the nozzle aren't there, the pump can't fill because it just sucks air back thru the nozzle.

If the ball and weight near the accel pump aren't there, the pump can fill but won't squirt - - fuel just gets pressed back into the bowl.

Good point!

The check ball and weight that are adjacent to the accelerator pump are in place, as are the ones under the nozzle. I'll pull the top off the carb and confirm it with photographic evidence.

So long as you know it's there, no need to tear down just for pictures. I just thought I'd noticed something maybe you weren't aware of.

I'll double check it. I'm looking at a used Yaw carb and mani that came off of a running car. Waiting on a shipping quote. If I can't figure this out by the time I get the shipping quote I'll have a Yaw carb on the way.