holley running rich when warmed up

[1977cherokeechief]

my jeep runs great until it is warmed up, i know it isnt the choke because it is open all the time,

sometimes i can give a little gas and it will die... if i put it to the floor it will start right back up but sputters and smokes black...

others i can touch the gas and it will run fine for about 10 secs and start missing out until it dies or i put it to the floor, to get rid of the extra gas,

i have a new cap/rotor/points, condesor, coil, plugs, plug wires,

i rebuilt the carb about a month ago (with a mechanics help), just so i could move it around, and it ran great for a couple days while i was working out the elec. problems i have been having:banghead: ...



anyways i have adjusted the screws all the way in and all the way out and no matter what i do it stays the same.

[will e]

Things to check:

Blown power valve.
Stuck needle/seat.

The needle/seat is easy to check, open up the bowl screw on the side and if gas dumps out, you have a needle/seat that is stuck open.
This is not uncommon on Holley's.

[XxJuicyBurgerxX]

I have been having the same problem with my Howell TBI. It runs kind of like the timing is off sometimes, missing a beat regularly, but others it is fine. and sometimes when I turn it off it wont start back up, and sometimes just dies for no reason.

Your problem might be a dirty fuel filter? It kind of sounds like the problem I had and all it needed was a new filter

[1977cherokeechief]

Things to check:

Blown power valve.
Stuck needle/seat.

The needle/seat is easy to check, open up the bowl screw on the side and if gas dumps out, you have a needle/seat that is stuck open.
This is not uncommon on Holley's.


thats not it.... the powervalve seems to work just fine, the jeep has never backfired... not since i put the new carb on it.

any other comments..... this maybe a newb question but..... is there only the 2 adjustment screws on the primaries that adjust the air/fuel, and then the idle screw????? or is there someother adjustment that it has???

[710 Burner]

The two screws are the idle screws. The screw on the side of the metering block is the mixture screw. You need to confirm that your float adjustment is correct.

[will e]

thats not it.... the powervalve seems to work just fine, the jeep has never backfired... not since i put the new carb on it.

any other comments..... this maybe a newb question but..... is there only the 2 adjustment screws on the primaries that adjust the air/fuel, and then the idle screw????? or is there someother adjustment that it has???

How can you tell the powervalve works fine?

[SaintCyr]

Maybe someone can help me out... Would a faulty vacuum advance do this?
Sounds like a float problem... Especially if its loading up AFTER you shut off the engine...

[drlocke]

If the float level is set right then likely it is the power valve (backfire noted or not) that is causing it to dump in gas. On the Holley carb on one of my trucks I agonized over it's running so stinking rich. Initially it was the bakelite float had absorbed enough fuel that its buoyancy was down. I replaced it, and the truck ran fine for a day or so, then ran rich again. :banghead: I replaced the power valve and that corrected the problem.

[1977cherokeechief]

i will pull the carb and bowls off to see if the floats are correct, what should i set them at for a 360???

[Ristow]

float level is not engine specific.set them per the holley instructions.

what model carb? most 4 bbl have a screw you remove on the side of each bowl,and externally adjust the float til fuel is at the base of the screw hole.

[will e]

use the sight plugs. On a level surface with the engine running the fuel should be just below the sight plug opening. Almost ready to dribble out. This is a great way to check if you have a stuck needle and or a problem with the float itself. After adjusting the level, While parked and running leave the sight open. Wait until the engine starts to run poorly. Is there fuel dumping out the sight hole? If there is, you have a stuck needle or a float going bad.