Spark plug color

[ChuckN]

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Looks a little lean. What say you? First drive was yesterday. Does have a throttle stumble so I have the accelerator pump on the setting that gives most fuel. Thinking about putting in the next stronger step up spring in the Edelbrock.

 

[Snoots]

Looks good to me.

 

[ChuckN]

Looks good to me.

Thanks, I’ve been playing with the accelerator pump adjustment arm on the Edelbrock, went from middle setting to the richest. Also, went one step up spring stiffer, and it seems a little bit worse or at least no better. The plugs don’t look rich by any means. But it definitely has a stumble from 1000 to 1500 RPMs when I really goose it. It backfired through the carburetor, and I know that the timing is set right. so I’m back to square one. New ethanol free gas in the tank, and I double checked for vacuum leaks.

 

[ChuckN]

Looks good to me.

At least I know I’m in range.

 

[ChuckN]

FWIW, carb jets, and rods are set to one step above stock 1406. I had orange springs in there, and I took them out and went with pink springs. Just has this nasty little stumble that happens when I step on it- but if I roll into it slowly, or once I’m above 2000 RPM, it is really happy.

 

[rusted nuts]

Don't think Your stumble or backfire has anything to do with Your carb. Thinking it's spark, Timeing, Maybe a vacumm advance.

 

[ChuckN]

Don't think Your stumble or backfire has anything to do with Your carb. Thinking it's spark, Timeing, Maybe a vacumm advance.

Spark is strong. I’ll check the vacuum advance!

 

[rusted nuts]

Is spark strong ALL the time??,, I had the wire break inside the insulation on pick up module under dist cap one time Ran good till I got into it then would want to die.

 

[ChuckN]

Is spark strong ALL the time??,, I had the wire break inside the insulation on pick up module under dist cap one time Ran good till I got into it then would want to die.

Good question, but I drove it 10 miles around town. It runs awesome! Just doesn’t like that one spot. So either it is a fuel or spark issue for sure- but otherwise it runs strong, and if I give ‘er the beans in other rpm’s, it sounds damn great.

 

[rusted nuts]

Odd deal there.

 

[Snoots]

I don't know squat about Eddie carbs but the off-idle stumble sounds like a jetting issue.

 

[ChuckN]

I don't know squat about Eddie carbs but the off-idle stumble sounds like a jetting issue.

Yeah, might be. Trying not to take the whole thing apart so I’m messing with the step up springs to have the fuel come in earlier or later and see which way to go. But as @rusted nuts said, I’m rethinking the vacuum advance and potential vacuum leaks. I just put a vacuum pump on the lines coming off the carb and they’re all airtight and when I pump up the advance I can hear it moving. Just quick checks before I head into work.

Tomorrow I’m gonna mess with the springs again and check that the timing is vacuum advance is actually working, and also do the spray-check with some brake cleaner and try to find an unforeseen leak.

 

[rusted nuts]

When You check the vacuum advance make sure it don't leak off.

 

[ChuckN]

With the vacuum pump test I did this morning, it is airtight and holds steady.

 

[SquareRoot]

Vacuum advance has nothing to do with acceleration. That's why you block it off when setting the timing. A stumble is 99% of the time a lean condition. If it bogs and catches up, it's a rich condition. I played with the 1406 for years before ditching it all for EFI. You need to play with the jet size, rods and vacuum spring in the secondary's. Regarding the plugs, reading the color don't mean much anymore with todays gasoline. My EFI is tuned at a perfect 14.7 AFR and they run white as a ghost. Tp properly read plugs, you normally run wide open throttle, shut the engine off and coast to a stop before the idle AFR contaminates them. Not very practical in a non-race car.