Black Smoke Under Full Throttle

[RazzaCaine]

Hey everyone, was driving at 80kmh earlier in third gear and was giving the car a squirt, went to put it in 4th gear and it slipped into 2nd gear instead. the engine sounded pretty angry and i quickly got it into 4th. as i changed into 4th i noticed in my rear view mirror a lot of black smoke. ive never noticed this before whenever i have given the throttle a bit of a stab. i know black smoke is never a good sign and has something to do with the oil, so should i be worried and whats the most likely problem? the engine never has oil pressure issues or over heating issues and generally runs extremely well not matter how much abuse or how much distance it covers in one go. the engine also does not use any oil. any help would be much appreciated

[soop]

Black smoke is unburned fuel.
Running rich lad.

[Darren_L]

^^ agreed
black smoke is easily fixed, far better than blue or white smoke

might need to fiddle with the carb. Did you have your foot dug in fairly hard on the throttle ? (from memory you are running a Quadrajet carb ?) If you were past about 3/4 throttle, then your secondary metering rods might be the wrong size.

[old mate]

x3 bulk richness on juice level. secondary metering rods too big, or you could possibly bend the secondary metering rod hanger (dodgy, but if you dont have any more rods or dont wanna machine what you have) and lean it off a bit.

to test it, get a mate in the car and get him to look out the back window when you plant the boot. then do the mods and get the mate back in the car to check for black-ness again.

[soop]

No one has addressed the fact that this has just randomly occurred.

Check for vacuum leaks bud.

[old mate]

didnt he recently get this car on the road though? i cant remember.

what size metering rods are they? or have they been made 'custom'

[soop]

Fairly sure he's running a standard quadrajet.

[old mate]

standard for a vb or from a different model?

they varied a bit depending on model iirc.

[soop]

Its a black motor with a small cam in it.

I think its a standard black motor Quady. From what I've read from his other threads. The fact he's never mentioned this issue prior says to me something he's changed has caused it or something has given up.

[RazzaCaine]

thanks for the quick responses everyone. ok just to clarify guys, its a '79 VB with a black 308 from a VK. it has a small cam, roller rockers, sports exhaust and a standard quadrajet that was issued in a VK (i have checked the id codes on the carby). i havent fiddled with the carby at all and ive owned it for 2 months with it being my daily for that entire time. My foot would have been 3/4 down on the gas and this is the 1st time i have noticed it. I drove the car again about half hour after this incident so i got onto a side street and put the gas pedal flat to the floor in 2nd and there wasnt any smoke that time round. i had suspicions that the car was running was rich as the fuel economy is pretty atrocious... i put about 45L of fuel in each week and if i granny the car (i.e. change gears at 2000rpm) i get about 250kms, if i stretch its legs (change gears at 4000rpm) i get about 150 - 200kms.

[Benboy]

Take your car to a Riad Transport Testing Station and have them check the levels of exhaust emissions. Your car might be illegal and in breach of Emission Control Act. Best get it sorted before authorities put it off the road. Good luck.

[RazzaCaine]

im 99% certain that the motor is perfectly legal. the previous owner had the engine in a VK which went through regency park vehicle inspection before it got transplanted into the VB. the VK passed fine as the cam is only small/medium. I also got pulled over by a police officer last weekend who insisted on inspecting my car all over and the only issue he had with my car is my left brake light wasnt working. He even thought the quaddie was a holley just because the air filter cover is chrome, I had to try so hard not to laugh. He didnt even care how loud the VB is, and believe me its loud, at idle its loud enough to hear half a block away. Ive passed police cars many, many times and they dont have a problem with the car so I dont think the authorities are going to bust me for emissions any time soon

[soop]

Carby may just have a had a little sook for that instance mate. They're good at that.

[RazzaCaine]

ive heard they can be a bit tempramental. one day when i have the money ill buy a wrecked vn ss manual and drop an efi v8 in

[soop]

Sounds like a plan LOL!

[ari666]

heh. missed this thread can i still put my 2 cents in?

quaddys are great for throwing fuel around in the bowl. if your cornering a bit fast it can slosh out of the whistle and dump a bit of fuel in the primary. too much fuel=carbon. also sometimes the primary pump is waaaay too rich for a bootfull, especially if you are cruising out of your power range, then floor it. it squirts a bunch of fuel in, which you dont use completely until your gotten back into your paower range (i.e. cruising at 2k rpm, power band is 3000) the unburnt mix comes out as carbon.

the joys of carbies mate they are by no means perfect.

[DerekP]

Your fuel consumption sounds (sadly) about right for city driving. Quadrajets are excellent carbies however they are overkill for a standard / mild 308 IMO (let alone 253's).