very high idle. fouled plugs. idle mixture screws not responding.

[Irish_Alley]

what gasket?

[1979C20]

I know what it is! Did the drop leak out of the passenger side of the carb? For a while, my float stuck at the top and it made my idle really high and ran like crap and ran rich. I beat the crap out of the top and sides of the carb with a screwdriver handle and hit a bunch of hard bumps on the road and it settled down.

[Irish_Alley]

lol i can see it now... well this pothole looks big enough hit it at 50 . if that’s it good, but if fuel can get out air can get in

[txchainsawgogi]

the 1/4 inch thick base gasket.

[jaredts]

Idle mixture screws not responding is generally vacuum leak.  I'm not sure of anything else that can cause that.  It would also cause high idle, so...

[txchainsawgogi]

just bought the last felpro base gasket my autozone had in stock... hope its all i need.

so, would a leak in the gasket cause my symptoms? i sprayed wd40 all around it yesterday and saw no sudden increase in rpms... just the steady climb it was kind of already doing.

[Irish_Alley]

yeah would cause high rpms not sure about the fouled plugs but its defiantly a problem. i would think it would cause you to be lean

[txchainsawgogi]

replaced the gasket... now instead of idling REALLY high, its only a little high... but i cant get the idle smooth.

its at 1100rpm but choppy, and in drive its at 600/550rpm but choppy.

how do i get the idle smoothed out?

[Irish_Alley]

what im thinking is when you where screwing in and out those screws you messed up the tune. i dont know where to start on tuning that carb but if you search the web it might tell you where to start

[txchainsawgogi]

what im thinking is when you where screwing in and out those screws you messed up the tune. i dont know where to start on tuning that carb but if you search the web it might tell you where to start

thats exactly what happened. a few days ago when the plug boot first melted and dipped the idle speed and made it ride rough, i must have messed with the fast idle cam(which i still know almost nothing about, tuning wise).

as of five minutes ago i finally got it to idle where it used to be (1000rpm in park, 550 ish in gear) BUT its still very rough in DRIVE.

i got it back to drivable thanks in large part to trial and error turning in/out between the fast idle cam, idle mixture screws and the idle screw at the throttle linkage.

now i just need to tune it again.

i dont trust my cars emergency brake enough to tune it in drive so im stuck waiting for my girlfriend to get home. bummer.

[greg1984GMC]

with the engine running (at idle ) and the choke fully open, look down the carb and see if
you can see any raw fuel dripping .   If so, open up the carb and check for proper float
adjustment.  If it's a fiber float, make sure it's not saturated with fuel, causing it to not
float and properly the needle valve.   Also make sure the needle valve and seat do
not have any debris in them.  Make sure the retaining clip that holds the needle valve
to the float is properly attached and not causing the float to hang open.

[txchainsawgogi]

i got it where it needs to be, its just a matter of movin' the screws around some more. the idle speed in drive is very choppy and eratic.

[1979C20]

Did you replace the fouled plug(s)?

[txchainsawgogi]

yeah all new plugs, all gaped correctly. new base gasket...no vacuum leaks.

one thing though, when doing a vacuum gauge tuning of the idle mixture screws:

what do i cap off, and where do i attach the vacuum gauge?

i had it attached to the port right under the choke pull off(passenger side)?

i had the front facing port capped and the vacuum advance capped.

[txchainsawgogi]

well its the end of my long weekend, with a full week of driving to work ahead... will the truck be ok even with the low idle?