Custom 454 won’t idle.

[Supercharged111]

It should have idled with one of those carbs on it.

Less than 10% between all cylinders, all good.

I've never dealt with a motor with that much cam and a carb, but I do know on a q-jet I'd be drilling the idle air bypass jets out for that much cam. That would keep the throttle plates in the range of the transfer slots so the thing stays on the idle fuel circuit and doesn't transition to the main circuit which would make it idle pig rich.

 

[Hipster]

Based on how black all the plugs were this morning I’d say it’s rich plus the inside of the brand new carb is already black like it’s one of my old used ones.

You need a fresh set at this point.

 

[Hipster]

I've never dealt with a motor with that much cam and a carb, but I do know on a q-jet I'd be drilling the idle air bypass jets out for that much cam. That would keep the throttle plates in the range of the transfer slots so the thing stays on the idle fuel circuit and doesn't transition to the main circuit which would make it idle pig rich.

Same as what's need for a Holley, never been in an Ebrock that deep because mostly limited to mild applications from my experience. Mopar guys pretty much use them as an Afb replacement direct bolt on. The ebrocks have a counterweighted VS secondary operating mechanism, and Mopar guys have gone to the ends of the earth trying to modify the secondary opening, trimming weights, etc. because it happens too fast/too early with low vacuum cams. More prevalent on the 750's than the 650's. 650 on a mild rv cam build actually dynamite pretty much out of the box.

454+ cubes, 230/[email protected] ebrock 750 would not have been my choice. Thinking 850/950 Holley DP. never been much into q-jets though I understand exactly what you mean.

There's other issues going on here. if the distributor is a few teeth off it could be the reason it's popping back through the carb @RPM. The plug shows it's not lean, fuel washing the cylinders might be an issue and driving it isn't going to fix it.

 

[Erik the Awful]

Here are my compression results from this morning also I was able to just feather the throttle enough to keep it rough idling around 600-800 rpm and the highest vacuum reading I got was 8. Thoughts?

I think most GMT400 owners would be jealous of those numbers.

 

[Cookscustoms]

So today I started with spraying carb cleaner all over the intake where it mounts to the heads as well as the base of the carb and it never revved up. So then I reconfirmed the distributor is pointing primarily between #1&#8(closer to one) on the cap and pointing at No. 1 cylinder in general, triple checked all my wires to confirm correct locations on the cap, installed a Holley 12-803 as recommended above and set it at 4-1/2 psi, reset my idle mixture screws to 2 turns out and bada bing the damn thing still acts the same. I’ve tried turning up the idle screw on the carb to the point where it will idle at about 3,000 but even then if not pumping the pedal it still slows itself until it stalls out. Any new thoughts or have I overlooked anyone’s suggestions? Thanks again gentlemen.

 

[Cookscustoms]

You need a fresh set at this point.

I think I agree but would it run at all if they were bad?

 

[Hipster]

I think I agree but would it run at all if they were bad?

yeah but it will pop and spit etc. if there's a fouled one in the mix. Once fuel/carbon fouled spraying them with brake cleaner etc. doesn't bring them back around.

 

[Cookscustoms]

yeah but it will pop and spit etc. if there's a fouled one in the mix. Once fuel/carbon fouled spraying them with brake cleaner etc. doesn't bring them back around.

Thank you for the input. I will change them out tomorrow morning and keep my fingers crossed.

 

[GoToGuy]

So you've done the musical chair carb thing . Any chance something is off in ignition land. At the beginning with pop and backfire, mixture, accelerator pump, something fuel.
After swapping numerous carbs, id tear into the ignition, coil , hei, cap , inspect recheck. Do have any computer controls involved, or is the Accel a stand alone hei?
It's just after carb swaps,; and the plugs still looking fouled rich, like there not getting a full power spark, maybe or intermittent spark. Just , to be thorough,

 

[Cookscustoms]

So you've done the musical chair carb thing . Any chance something is off in ignition land. At the beginning with pop and backfire, mixture, accelerator pump, something fuel.
After swapping numerous carbs, id tear into the ignition, coil , hei, cap , inspect recheck. Do have any computer controls involved, or is the Accel a stand alone hei?
It's just after carb swaps,; and the plugs still looking fouled rich, like there not getting a full power spark, maybe or intermittent spark. Just , to be thorough,

HEI is stand alone. After I swap the plugs I reckon I might switch to MSD or ??