Chevit
1/2 ton status
Well I have now replaced the coil and put a new dist. cap on it...still doing the samee old $hit any more ideas?
CK5
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Carb or Dist.
- Thread starter Chevit
- Start date
mountainexplorer
1/2 ton status
My Crew Cab was acting similar last fall. At idle once in a while it would run fine, then kind of sputter and act like it was loading up. Driving it, only once in a while it would start backfiring through the carb. But it started to get to the point where it was doing it more and more often.
I checked everything I could think of. Then I took the old Q-jet off (it was always a good dependable carb, but it had alot of miles on it), and I put another carb on, and it runs fine now.
I checked everything I could think of. Then I took the old Q-jet off (it was always a good dependable carb, but it had alot of miles on it), and I put another carb on, and it runs fine now.
Chevit
1/2 ton status
now I replaced the dist. same old crap... /forums/images/graemlins/angryfire.gif
Chevit
1/2 ton status
Well swaped out the carb and it does the same thing , did a compression check all is good 135-140 all around . The kid took it for a spin around the neighbrahood and f ked up the rear end
I am lost on what to try next
I am lost on what to try next
elacruze
1/2 ton status
First, if you haven't already, check that the distributor advance isn't siezed up. That would explain why your timing was advanced, if the shaft can't return to initial timing. Rev it with the timing light attached and see that you get advance/retard with rpm. More likely though, is that the carb has some gunk in it somewhere. Take the top off the carb (one screw for choke linkage, roll pin for pump lever, two screws hiding in the primary venturi waiting to fall into the engine upon removal) Blow carb cleaner through the little brass tubes in front of the primary venturies. Blow carb cleaner through the idle adjustment screw holes. Try to see that the CC blows freely into the venturies through those holes. Replace your accel pump hardware, and grind about 1/8" off the top of the pump shaft. What year/size is the engine? The QJ carb has a spring controlled 'power valve' in the primaries which opens when manifold vacuum falls-if you have the smog spring, you will have lean primary mixture until the secondaries open. IM me if you want the richer spring-I had to buy a bag of ten to get the one I needed. If you have the electric QJ, there's no spring. While you have the carb top off, you'll see that two of those brass tubes are actually tiny orifice plugs. Open the holes in them .020 to .040" more than they are. That richens the tip-in mixture. If it's still snorting, like mine is, you'll have to increase primary main jet size. Mine is a '77 454 Cali motor, which came with 71 main jets and .038 primary needles. It appears that even with the rich spring I'll have to go up to .076 main jets.
Oh-before you do any of this, spray gumout around the base gasket and all vacuum sources to determine if you have major air leaks, and if there is any question about it buy a rebuild kit ($16.00 at NAPA)which gives all new gaskets and pump, etc.
Oh-before you do any of this, spray gumout around the base gasket and all vacuum sources to determine if you have major air leaks, and if there is any question about it buy a rebuild kit ($16.00 at NAPA)which gives all new gaskets and pump, etc.
Check the throttle plate bushings at the bottom of the carb for wear, They will wear out and cause a vacumn leak. It is almost definately in the carb. It sounds like a vacumn leak problem or an idle circuit is plugged. Try to turn the carb adjustment screws in or out a little and see if it makes a difference, and check that your idle speed is correct. Just my 2 cents
