Four Carbs, all loading fuel at bottom of intake

[sprice]

Need some thoughts. Every carb I have tried is bogging at idle and above and leaving fuel at the bottom of the intake. Floods and stalls. 3 Edelbrocks, one Holley and one Slayer tried. What I have is:
- rebuilt engine and components
- RV cam
- 906 Heads (rebuilt, ported and polished)
- MSD 8387 Distributor (tried two, no difference so kind of eliminated an electrical issue)
- edelbrock #7193 Performer RPM intake
- vacuum is 16-18 hg (steady when timing is pegged, no bouncing)
- timing is 14 BTDC, seems to run smoother at 18-20 however still has flooding issues
- all vacuum ports plugged on intake and carb except PCV hose is connected to carb
- timing is correct on damper and timing cover marker
- timing chain marks are correct (disassembled after running to verify)
- fuel pressure is 4.25, Was 8 psi so purchased a regulator which brought that down to Edelbrocks spec. Still flooding however, even with the Holley.
- Tried propane along the intake ports along the head, no difference in rpm detected
- rebuilt the Edelbrock 1411 with new kit and no difference
- changed plugs twice due to fouling, NGK, then to Autolite 85's. Same fouling on both.

NEW Info:
- Mopar HP manifolds
- heat crossover is blocked off (don't think there is one on the 7193 intake)
- block-off plate in the exhaust manifold is removed
- boil cleaned the 1411, then with carb cleaner and air blast
- changed the springs from pink to silver per Edelbrock manual
- floats checked and adjusted to 7/16" on close and 15/16" drop
- no ballast resistor (however mike66chryslers has noted something i need to check)
- changed coil with new, no change however my wiring could be the culprit as noted above

If I take the PCV hose off the carb port it runs smooth like it should, however cannot get to idle or below 1200 rpm. Tried two PCV valves, no change. Seems like the more air introduced to the intake, the smoother it runs. I thought if there was an air leak in the manifold it would cause a lean condition, however when it stumbles and stalls after checking everything, remove the carb and fresh fuel at the bottom of the intake and black plugs.

Any thoughts?

I will check my coil wiring and get back to everybody.

 

[commando1]

Any thoughts?

Damn. At this point I would have to walk away for awhile before going mad.
So far you've done all the right things.
I'll be watching for opinions.

 

[sprice]

Damn. At this point I would have to walk away for awhile before going mad.
So far you've done all the right things.
I'll be watching for opinions.

Done that several times. Running out of walkways.

 

[david hill]

Is the heat crossover passage been blocked. Check also for a restricted exhaust or stuck heat riser

 

[John Kirby]

Carb jetting? Possible accelerator pump putting out too much fuel? Try reducing pump setting. Check jet size and the metering rods (and their springs). If it runs better with more air that indicates way too much fuel. Download the carburetor tuning guide from edelbrock. I suspect the metering rods and/or springs are incorrect and letting way too much fuel in. That's that the tuning guide says. Might as well get the manual for the 1411 too. It has calibration charts to help with tuning.

Not sure but did you accidentally swap the primary and secondary jets during the rebuild? Not sure if that is possible but something to check. They have their size engraved into them in tiny numbers.

 

[CBODY67]

Sounds like the air bleeds in the venturi cluster, for the idle circuit(s), might be blocked/clogged, which will cause the circuit to go "full rich". Hard to envision that all of the carbs have this issue, though.

Reason I say this is two-fold. Once, in a Holley carb seminar, the Holley person mentioned that a "shade tree" method of getting the correct idle mixture adjustment without a tach or vac gauge was to take your little finger and place it over the air bleed hole in the top of the carb, just under the choke blade. The outer hole, as I recall. He stated that when you block that bleed, the circuit goes "full rich". What the engine speed does after that indicates if the idle circuit is adjusted "lean", "rich", or "close to correct". If the speed goes up and then down, then the adj is too lean. If it just goes down quickly, the adj is too rich. If it might increase just a hair, then it's just a tad lean, by comparison.

The OTHER thing is that when I was diagnosing a persistent "die when the carb gets off of fast idle when cold" situation on my '80 Newport 360 Carter BBD 2bbl, I got some small wire stock, bent one end of the wire, then placed it into one of the idle air bleed tubes in the carb's venturi cluster. When I'd do that, I could see that side of the venturi start to drip gas, reliably. I removed the wire from that tube and put it in the other tube. Same thing on that side. This was something like .040" wire, so not very big at all. But that was enough decrease in the effective diameter of the air bleed to put that side of the circuit into a very rich mode.

IF the carbs used were used, rather than new, it could be possible that some of them have a bit of clogging in the air bleed circuit for the idle system of the carb. Easy enough to fix, provided that the gaskets seating that circuit (supplying air into the circuit, as a calibration function, in a "pressure-bias sort of orientation) are not blocking the holes in the venturi cluster. If the gaskets are correct and fine, then look further into the idle air bleed circuit for a blockage.

Otherwise, might be heavy floats, but hard to suspect that they ALL were that way. As some of the other things which might cause the fuel circuits to go "full rich", too.

A blocked heat riser passage can affect cold-running until the engine warms up enough for the manifold to get warm and vaporize the fuel sufficiently. Nothing new there as everybody who might have done that has some experience in that situation. But I somewhat doubt that that is the only issue at play here. The noted Edelbrock manifold is "cold" due to the fact that the bottom of the intake is not affected by engine oil splash on the bottom side of it, even with heat in the crossover, but not unlike a normal Chrysler intake without the insulation bag under it, so air flows under the intake at all times. Minor issue, though.

More air = leaner effective total mixture, as you have determined. Something's not correct somewhere. Whether it might be consistently bad floats and adjusted levels thereof, poor ignition output (one constant, possibly, in the whole affair) issues, incorrect gasket(s) under the venturi clusters, etc.

Keep us posted, please.

Just some thoughts and observations,
CBODY67

 

[commando1]

The point is, he's gone through FIVE carbs. Just saying....
It ain't the cab.

 

[Mike66Chryslers]

Carbon-fouling the plugs and won't idle sounds like an ignition problem I was having recently. In my case, my ECU (Pertronix Ignitor-I) was failing, but hooking it directly to the battery improved the symptoms.

How have you wired-up power to the distributor? There is an appnote for your distributor that says it needs a solid 12V and no ballast resistor. They advise that power through the ignition switch may still have too much droop and, if so, install a relay to get full battery voltage. As a test, you may want to try temporarily wiring the distributor power right to the positive battery terminal.

See the link to "Supply Voltage Addendum" at the bottom of this page.
MSD 8387 Chrysler 426-440 Ready-to-Run Distributor

 

[detmatt]

The engine is getting its air from somewhere else besides the carb? Allowing the fuel to fall out of the charge as it passes through the intake?

 

[sprice]

Carbon-fouling the plugs and won't idle sounds like an ignition problem I was having recently. In my case, my ECU (Pertronix Ignitor-I) was failing, but hooking it directly to the battery improved the symptoms.

How have you wired-up power to the distributor? There is an appnote for your distributor that says it needs a solid 12V and no ballast resistor. They advise that power through the ignition switch may still have too much droop and, if so, install a relay to get full battery voltage. As a test, you may want to try temporarily wiring the distributor power right to the positive battery terminal.

See the link to "Supply Voltage Addendum" at the bottom of this page.
MSD 8387 Chrysler 426-440 Ready-to-Run Distributor

Will check on this. There is more than one wire on the coil. Thank you.

 

[Knebel]

Will it stall when you turn the idle mixture screwes all in? Throttle blades open too much and transfere slot exposed?

 

[1970FuryConv]

The engine is getting its air from somewhere else besides the carb? Allowing the fuel to fall out of the charge as it passes through the intake?

Also, "changed plugs twice due to fouling, NGK, then to Autolite 85's. Same fouling on both." @sprice Do you have a pic of the fouled plugs? If not, were they fouled with black soot, grease?

 

[Big_John]

Since you disconnect the PCV, and it runs better, that doesn't make sense that its a vacuum leak. That means it's too rich.

Since it also runs better with more timing, I'd be suspect that the timing marks are off. So I would advance the timing some more and see what happens.

 

[Ripinator]

The point is, he's gone through FIVE carbs. Just saying....
It ain't the cab.

Ninety-seven percent of all carburetor problems are electrical. . .

 

[Knebel]

Hold up. If the plugs are fouling... that means there is spark and too much fuel. See my previous post. Another area...since it tansfered with the carbs is FUEL PRESSURE...get a gauge and a regulator and set it to 5psi.

Could also be vapor lock if it stalls... boiling fuel in the bowls too. Those are areas I'd check.

 

[68PK21 440.6bbl]

.

 

[sprice]

Hold up. If the plugs are fouling... that means there is spark and too much fuel. See my previous post. Another area...since it tansfered with the carbs is FUEL PRESSURE...get a gauge and a regulator and set it to 5psi.

Could also be vapor lock if it stalls... boiling fuel in the bowls too. Those are areas I'd check.

Did that after two edlebrock trys. Have a regulator set at about 4.25 (just over 4 psi.

 

[sprice]

Since you disconnect the PCV, and it runs better, that doesn't make sense that its a vacuum leak. That means it's too rich.

Since it also runs better with more timing, I'd be suspect that the timing marks are off. So I would advance the timing some more and see what happens.

Disassemble front of engine after break-in and rechecked timing marks and confirmed the marks with Comp Cams. Also checked manually with piston stop and visual for TDC.

 

[sprice]

Ninety-seven percent of all carburetor problems are electrical. . .

Try and get to that coil thing over next few days. I think there is something here. Have some unconventional wiring going on here.

 

[sprice]

Will it stall when you turn the idle mixture screwes all in? Throttle blades open too much and transfere slot exposed?

On the Holley yes, on the 1411 it did, then didn't and then couldn't get it back to stalling by turning them in. Don't know what I did to change anything.