Engine ran perfect, plugged carb vac line on back no run

[jjg73]

First happy Easter if anyone sees this today. Title is lame I know, but really scratching my head, again. Built my 340, put on an asv2 650 carb on and fired it up yesterday. Thing ran amazing at first. With the earmuffs on I didn't hear the vacuum leak i had at first. Stupid me forgot to plug the rear port for brake booster. Put the plug in, now I can't even get an idle without holding it WOT.Took the plug out, same damn thing. What on Earth could I be missing? Has to be something stupid. All cylinders still firing as when I put a mist of water on each header pipe I get instant sizzle. Smells super rich too. Idle mixture screws are backed out 1.5 like from factory. Thanks!

 

[Ernie ingling]

Is it bleeding over?

 

[70chall440]

Ok, so if it runs with a massive vacuum leak but doesn't without the leak then my guess would be is that it is flooding.

 

[Johnpat]

Check float,my a be s..if has a hole
Seen them fill with gas

 

[jjg73]

Ok, so if it runs with a massive vacuum leak but doesn't without the leak then my guess would be is that it is flooding.

It won't run either way now is what's wrird

 

[Photon440]

Check if the plugs are soaked with gasoline. If it's flooding, find out why. Perhaps dirt in the needle and seat? Is the carb in good condition?

 

[70chall440]

Go back to the beginning, pull the plugs and clean or replace them, check over the carb, plug all of the vacuum lines, and ensure you have spark. The engine wants to run, you just have to set the right conditions.

 

[jjg73]

Carb is brand new out of the box, along with plugs and wires. One thing I want to try is maybe new plug wires as they are from Rock Auto and not a fan of them, it's just weird how it ran exactly perfect, plugged the vacuum port now it's trash, which is why I'm lost haha

 

[turbine68rt]

Are you getting any fuel leaking from the throttle shafts?

 

[jjg73]

Are you getting any fuel leaking from the throttle shafts?

Negative

 

[WP29440SE]

have you compensated for the vacuum leak by turning the idle screw in

 

[70chall440]

Not really weird at all, the engine was dry and everything was new, once you fired it the plugs most likely got fouled. "New" does not mean "good" or proper, I think most of us have bought new parts that failed quickly or even immediately.

 

[turbine68rt]

Does the choke seem to be in the correct position and functioning properly?

 

[jjg73]

have you compensated for the vacuum leak by turning the idle screw in

Yes I returned it back to 1.5 turns out

 

[jjg73]

Does the choke seem to be in the correct position and functioning properly?

Good question... I didn't look at the passenger side positions before and after. What should it be doing there?

 

[WP29440SE]

Yes I returned it back to 1..5 turns out

I am talking about the curb idle screw not the mixture screws. if the idle screw was sitting at it's resting point the carb will run with a massive vacuum leak, but once plugged you would have to turn the idle screw in to your desired rpm. the choke will have to be open at that point as well. I don't know if the factory pre-sets the curb idle screw

 

[turbine68rt]

Good question... I didn't look at the passenger side positions before and after. What should it be doing there?

Is it opening fully after a few minutes of running? I'm assuming you're running an electric choke.

 

[jjg73]

I am talking about the curb idle screw not the mixture screws. if the idle screw was sitting at it's resting point the carb will run with a massive vacuum leak, but once plugged you would have to turn the idle screw in to your desired rpm. the choke will have to be open at that point as well. I don't know if the factory presents the curb idle screw

I did turn it in some but not a whole lot. Another thing I noticed is I had my distributor vacuum line on the passenger side should I swap them over too?

 

[turbine68rt]

Passenger side is ported vac. Mainly for distributor advance like the original avs's. What timing are you running at idle with advance hose plugged and also at 2500rpm?

 

[1 MEAN66]

How about Is it getting fuel? Electric pump, mechanical, If plugs were not wet. Did Supply dry up. As said above Start at the beginning.