Edelbrock carb stumbles

saudivette

saudivette

Clueless In Sandland
Joined
Mar 24, 2008
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2,633
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Aussie expat in Saudi Arabia
I have an Edelbrock 1407 on my engine. I spoke to the guy that owned it ages ago and he said he put a 350 Edelbrock Performer crate engine in it (years ago now). Lord knows what the specs are though.

I haven't changed anything in the dizzy or carb setup only cleaned everything up and put it all back together. I have removed the choke setup though.

I tried tuning it today and with the vacuum advance disonnected I tried running it around 12* BTDC and it idled like a turd. After messing around it seems happy around 16-18* BTDC. But, when I punch the throttle, the engine stumbles. if I floor it it coughs and splutters and I have to goose the throttle to recover it.

I screwed the mixtures screws in until the engine started to bog down, then tried turning them out 1/2 a turn, a full turn, 2 turns etc. Even hooked up a vacuum gauge and messed with the mixture screws until I had the highest vacuum reading between lean and rich (about 6") but it still stumbles.

I gave it a while to cool down then took the top off the carb and checked the float levels. They were both out a bit so I adjusted them and put them back. Fired up the car and it still stumbles.

The accelerator pump/piston was set on the hole closest to the carb so I moved it back one hole - still no change.

So, am I under or over fueling? Anything else I can be messing with or should I get a needle/jet/spring kit? :huh:

Any ideas?
 
After years of sitting and drying out etc, you probably need a kit and a thorough cleaning of all the passages etc assuming it ran properly before.
Accelerator pump probably dried and brittle.
I wouldn't bother until you are ready to start driving it.
 
010752 said:
After years of sitting and drying out etc, you probably need a kit and a thorough cleaning of all the passages etc assuming it ran properly before.
Accelerator pump probably dried and brittle.
I wouldn't bother until you are ready to start driving it.
Click to expand...
I rebuilt the carb 18 months or so ago (probably closer to two years) and cleaned it and put a new kit through it then. The car fires up and runs ok and is drivable but can't punch it "off the line" so to speak. I really can't remember how it ran before but I would have thought the stumbling would have pissed me then too and I would have remembered it.

I had the accelerator pump out today and it's still nice and pliable...
 
Change the accelerator pump rod to a position further inboard on the arm, that will increase accelerator pump shot
 
Twin_Turbo said:
Change the accelerator pump rod to a position further inboard on the arm, that will increase accelerator pump shot
Click to expand...
It was in the hole closest inboard and it was stumbling so I moved it out one hole in case the pump shot was over fueling. I'll put it back where it was but the stumble will still be there...
 
Hook dizzy to manifold vac, plug ALL other vacuum lines, including brake booster, actually the easy way is to pinch the hoses one at a time, note any idle change....that's the leaky line....you maybe have several....especially that headlight setup....

;)
 
I got hydroboost and McSpeed electric lights :huh:

I've read as many people say not to use manifold vacuum as who say to use it for vacuum advance. Mine was hooked up to ported vacuum but I left it hooked up to manifold vacuum today. Didn't notice much difference though, but I was concentrating on trying to get the carb to stop farting when I jabbed the throttle
 
You'll have to try it with the squirter nozzle, a larger one will shorten the pump shot delivery time, a smaller one will give a longer duration. Fuel amount will be the same, just the delivery duration. If it stumbles, try a shorter shot (larger nozzle)
 
Twin_Turbo said:
You'll have to try it with the squirter nozzle, a larger one will shorten the pump shot delivery time, a smaller one will give a longer duration. Fuel amount will be the same, just the delivery duration. If it stumbles, try a shorter shot (larger nozzle)
Click to expand...
Not quite following you mate. I'm assuming I need a kit with a larger nozzle in it?
 
saudivette said:
Twin_Turbo said:
You'll have to try it with the squirter nozzle, a larger one will shorten the pump shot delivery time, a smaller one will give a longer duration. Fuel amount will be the same, just the delivery duration. If it stumbles, try a shorter shot (larger nozzle)
Click to expand...
Not quite following you mate. I'm assuming I need a kit with a larger nozzle in it?
Click to expand...

Let's say you want to force 1 quart of fluid thru a nozzle (or a hole). At the same pressure it takes longer to force the same fluid thru a small hole vs a larger hole.
A larger nozzle opening lets the fuel pass thru faster. It will not supply more fuel but the same amount of fuel quicker.
 
MYBAD79 said:
saudivette said:
Twin_Turbo said:
You'll have to try it with the squirter nozzle, a larger one will shorten the pump shot delivery time, a smaller one will give a longer duration. Fuel amount will be the same, just the delivery duration. If it stumbles, try a shorter shot (larger nozzle)
Click to expand...
Not quite following you mate. I'm assuming I need a kit with a larger nozzle in it?
Click to expand...

Let's say you want to force 1 quart of fluid thru a nozzle (or a hole). At the same pressure it takes longer to force the same fluid thru a small hole vs a larger hole.
A larger nozzle opening lets the fuel pass thru faster. It will not supply more fuel but the same amount of fuel quicker.
Click to expand...
No, I got the theory bit but was asking if smaller/larger nozzles were available in a kit...
 
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