Ive been trying to figure out what to do about a rich wot bog. All other driving conditions are great! When Im at a stop and slam the pedal it chokes for a few seconds and then goes. I say its a rich bog because of the heavy fuel smell in the exhaust after takeoff. This is a stock 350/350/4 barrel. Although Quad is not original. Any more info need just let me know...
It's way more likely to SMELL "rich" when in fact the fuel mixture is so LEAN that it misfires. An actual rich mixture doesn't smell so bad because the hydrocarbons burn but the CO doesn't have extra oxygen to form CO2--and CO is odorless. First Guess: bad accelerator pump Second Guess: Improper tuning of the secondary air valve including a defective choke pulloff.
That does make sense. well just got back from the track and seams the problem isnt a problem unless its cold... It ran wot beautifully after driving 40 miles to the track. Other times the car hadnt been driven more than a couple blocks. Thanks for the info im sure theres still more tuning to do.
that is normal for a engine with a carb. it even happens on tbi fuel injected engines. if it did it all the time then i would say accelerator pump. randy:beers2:
More than likely it is your idle mixture screws being set too rich which is causing a stumble. At first when I read this i thought of the infamous quardrajet bog from an incorrect vacuum break setting which lets the secondary flap open too quickly but this is likely not your issue. While you are poking around confirm full throttle opening.... Have you set the idle mixture screws to get highest vacuum in gear at idle? if not this will help BIGTIME. The most underestimated part of the q jet setup is the idle mixture settings because you can not transition off the idle circuit properly if it is too rich or lean. Other than that and the vacuum break adjustment the q jet is dead easy to make run well compared to other carbs.
one major problem (whether it is related or not) is at full throttle something is sticking making it just a little difficult to stop. I have to step on the gas a few times to release. Ive checked the linkage and didnt see anything obvious. any suggestions?
have you tired some penetrating oil on the linkage points? Sounds like a throttle return spring not hooked up or not enough tension.
Check the carb by hand, I had a new carb spacer gasket be sticky on me. Had to by hand work the linkage back n forth to WOT and back. Probably cause it was a new gasket I dunno but it made the secondary stick a bit till I worked it good by hand.
just got in from doing that and found the secondary rods are getting stuck somehow. They come up to far and wont go back in without playing with them a little. what should i do about that?
pics or a small video may help. I just can't se it in my head rigth now or to lazy to go pop my hood n look
Does the choke work properly? No, it isn't. There should NOT be bogs, sags, hesitation, or misfire. If there is, something is WRONG.
Choke is not connected due to linkage issues. Carb was bought as a stock replacement, but from the numbers on the carb it came from a 69 olds bigblock and wont connect.
You have issues with the engine driveability when it's cold. You have no choke. Yup, that's what happens... Time to sort out those linkage problems. What kind of choke is on your carb? Integral or divorced? What is the intake manifold set up for? Photos might be helpful.
here are the pics carb normal carb stuck choke assembly (one detached original link) Hope this helps paint a picray:
I see two missing linkages: There's no linkage down to the divorced choke coil. (I don't see a choke coil, either!) There's no linkage from the choke pulloff to the secondary air valve. This linkage would positively pull the air valve shut when you take your foot out of the throttle. It also regulates how fast the secondary air valve can open. Now, the air valve should shut on it's own; and it doesn't. Might want to remove the secondary metering rod hanger (one tiny screw) and pull the hanger and the two rods out of the carb. If the secondary air valve still sticks--it's not the metering rods that are the problem. Perhaps the air valve spring isn't adjusted tight enough--or--perhaps the air valve is hanging up on a casting irregularity; or on some overhanging air horn gasket material.
disconnected the hanger and it came right down with no sticking after that. so i do beleive the rods to be coming out of their place and not falling right back in without a little jiggling. what can be done about this?? as for the choke im not to worried about its functioning as of now because it will only be raced at normal temp and have no problems starting in texas weather.
yes it is if the engine isnt warmed up yet. this is because of the fuel collecting on the walls of the intake manifold. as soon as you open the throttle it sends a bunch of air/fuel into the cylinders but when the engine is cold most of the fuel sticks on the walls of the manifold. thats why the choke is there, to block off air so it sends an overly rich mixture into the cylinders to compensate. when the engine is warm the fuel vaporizes easier so this doesnt happen as easy but it still happens, you just dont feel a hesitation because of the accelerator pump squirting the extra fuel in when you mash the throttle. this happens to any engine with a wet manifold. its a natural occurance with a carb or tbi. the only time you should feel it is if you try to drive the car before its warmed up. randy:beers2:
As Schurkey pointed out, you are missing a link between the front vacuum break and the secondary air valves. The vacuum break slows the air valve movement down. Without that link, you will have a bog for sure. You need that link, it is not optional. Check the hanger carefully, it may be bent where the secondary rods hook into it.
True. Fuel doesn't vaporize well when cold. True. The additional fuel makes up for the stuff that doesn't vaporize. True. Whack the throttle open, and fuel falls out of suspension; puddles on the manifold floor, etc. The accelerator pump adds enough additional fuel to compensate. NOT true. If the choke and accelerator pump are working properly; and the intake manifold and air cleaner are heated as GM intends--there will NOT be bogs, sags, hesitation, or misfire. If there is, something is WRONG. (Put another way: You should NOT feel the bogs, sags, etc. because the carb or FI has compensated appropriately.) It DOES take a richened mixture to accomplish this; that's what the choke and accelerator pump are for; and why TBI has a cold-engine enrichment along with an acceleration enrichment. Exhaust emissions are increased--but--the driveability should be SEAMLESS.
As well the olds big block carb will not be jetted correctly for the Buick 350 and it will never run right BTW. Find a Buick 350 carb.
