View Full Version : What would cause black smoke and Ö..

05-29-2007, 03:11 PM
Iím just a trial and error back yard mechanic and I know a bunch of you know what the hell youíre doing so here is a question.

You might have read in another post that my jeep is causing my neighbours to come over to my house and tell me that my Jeep is making their family sick. Itís been only running this shitty for the last couple of weeks and itís off the road till I can figure it out.

I have a rebuilt 360 that is about a year and a half old with a 670 Holley Truck avenger carb. With it running warm or cold it turns out more black smoke then an old Diesel. On the passenger side it also drips out a black liquid Ö.raw gas?

The Choke seems to be working and the gas level on the carb is where it should be which is below the sight glass but can been seen if you shake the truck. I checked the plug wires and they seem to be tight.

What can you suggest I look at? The weather is here and itís killing me not to be driving it

05-29-2007, 04:33 PM
Black smoke generally gas...air filter? PCV? Choke stuck? Running on all 8? :dontknow:

Sorry..choke seems to be working. Maybe take the air cleaner off and hold the choke wide open and see what happens, did you put anything in the gas and carb when you parked it?

05-29-2007, 04:36 PM
Air filter is new, PCV valve is about 3 months old, Electric choke is working, I’ll take a closer look at the plug wires

05-29-2007, 04:37 PM
hopefully your stupid neighbours did'nt put anything in the gas tank:dontknow: :eek:

05-29-2007, 04:37 PM
change the fuel pressure regulator it is mounted on the back side of the carb silver thing with a vacuum line connected to it 3 screws holding it on. had the same problem with my 318 changed the fpr and no more black smoke they cost about 115$ at lordco or napa.

05-29-2007, 04:40 PM
hopefully your stupid neighbours did'nt put anything in the gas tank:dontknow: :eek:

jeez scary but that's a good point. :eek:

05-29-2007, 04:43 PM
This Carb has about 5000km on it and was a replacement of the same carb that was running shitty.

05-29-2007, 04:45 PM

05-29-2007, 04:46 PM
Sounds like a simple carb adjustment to me.But i really don't know anything.

05-29-2007, 05:04 PM
I still say you have a stretched chain and or a cooked valve (or other internal engine problem ) . Pull the dist cap off and see how many degrees play/slop you have between you ignition/valve timeing and crank position when you turn the crankshaft back and fourth .
next do a compression test .

third start to cry at the results[j]

05-29-2007, 05:47 PM
Have you checked the timing? sounds like you are way out. How old is the gas?

What did it run like when you parked it? This could tell us alot

05-29-2007, 06:21 PM
you're running rich really rich and that black liquid is carbon fouled unburnt gas and some water. If you continue to run it really rich you'll wash your rings right out and have a fucked motor. I agree with the fuel presure regulator possibly bein the problem and or mixture screw backed out or choke stuck closed or partialy closed. Timing could be out but I doubt that would cause what your describing.
Pull your plugs and check their color if they are black then you are rich (burning oil also makes em black)

05-29-2007, 07:50 PM
-check your air filter, if its dirty you could be choking you engine.
-fuel pressure reg. sounds like anotehr good chance
-change the plugs, they will be fouled up if you've been running that rich
-any chance your butterfly valves are sticking/tight?

05-29-2007, 08:24 PM
Carb is too,oo,oo rich. Qjet time?

05-29-2007, 11:04 PM
Might need to put a rebuild kit on the holley.They like to leak through the metering block gaskets,accel pump gaskets,power valves,throttle plate,etc if they sit for any lengthy period of time.

If the carb bores are wet anywhere while its idling then ya know thats what it is.

Also:possible vacuum leak that is being compensated for with a richer mixture.
Manifold vacuum port on back is common to miss for not being plugged off or used.

Also check BOTH gas levels...front might look ok but back one might have crap in the needle/seat assembly and be seepin.

05-29-2007, 11:38 PM
Have you set your idle mixture adjustment? Sounds way too rich at idle. If fuel pressure was high, the float adjustment would show high, ie: pouring out the hole in the side of the bowls if it has that kind.

Start with one side, turn idle mix screw in 'til the engine rpm starts to drop, turn back out 1/4 turn. Do the same for other side. May not pass aircare that way, but should be a lot leaner and not puke so much HC's out the tailpipe.

I've also seen new Holleys screwed up from factory. I have always said Holleys are good for one thing, the drag strip. Period.

Like Pumpkin said, put a Q-jet on it and you won't have to touch it ever again. Just make sure it's set up by someone who knows what they're doing.

05-30-2007, 12:41 AM
replace your power valve behind the float bowl

06-01-2007, 08:45 PM
Do you have dual exhaust or single, can you tell what bank of the engine is rich or is it both, if it's both i too would say power valve. If it's only one bank i would look at mixture screw on that bank. Power valves are known to blow out or leak. Yours may also be wrong for your engine, yours may be opening to soon. They are made to open at different vacuum settings, you may need to go to a lower rating ( lower vacuum to open ) Vince

06-01-2007, 09:45 PM
start from beginning withe the carb set them back to the start . dail it in to fact settings [cheers]