Carb problem??
Thread Starter
Intermediate
Joined: Dec 2017
Posts: 42
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Carb problem??
Hello friends, I have a problem, now my Corvette stutters while driving. Sometimes I also hear some bangs. 350 with Rochester 4brl, new ignition cables, new ditributor, new sparks...What's wrong, and what's the solution? Thanks for your answers.
Burning Brakes
Joined: Dec 2003
Posts: 1,147
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There are some very knowledgeable people on here but unless you provide them with some more details they probably won't be able to help you that much,such as did the problem just start,was there any thing that precipitated the problem?Does it do it when it's cold or hot?,cruising or accelerating?It could be as simple as bad gas or as serious as ---------.
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
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Heres some general stuff I dealt this month.
Start your car and get it warm and idling. Pull one spark plug wire at a time from the distributor and see if the engine rpm changes. I just had a series of problems and one of them was the right side of my carb clogged so I didnt have any gas flow to the 4 cylinders that run off that side of the intake (2,3,5,8.). It was a progressive problem and got steadily worse as I was doing some test runs for the other problems. I also have a large cam so I thought the rough idle was normal and the stuttering and lean running was ignition. I did have an ignition problem too but that is another story.
this will check for a dead cylinder and a fuel problem if your spark is good. I had good spark to all cylinders.
next recheck your distributor for vacuum advance issues. (The other problem) You already have it warmed up from the first test, so disconnect the vacuum advance and plug it with a golf tee. Take it for a spin and see if it changes. The stock distributor has a plastic sleeve on the end of the arm for the vacuum advance that acts as a limiter. When the plastic fails and it falls apart you get too much advance. The fix is a brass sleeve you can get in a rebuild kit. You can get Lars paper s and it states the " all in" advance setting, the max mechanical advance you should have and the total vacuum advance
You could also not have enough mechanical advance or too much. When was the last time you timed your motor. I see you changed the plugs, wires etc..When you did this did you change the points and did you set the dwell correctly?
You could also have a bad fuel pump and your starving the engine under acceleration, you need a fuel pressure gauge inline and you can just blip the throttle and see if it goes up to 8 or 9 psi. I had this happen, the axle that was pressed into the casting that the rocker arm rotated on sheared out of its
little arms.
Start your car and get it warm and idling. Pull one spark plug wire at a time from the distributor and see if the engine rpm changes. I just had a series of problems and one of them was the right side of my carb clogged so I didnt have any gas flow to the 4 cylinders that run off that side of the intake (2,3,5,8.). It was a progressive problem and got steadily worse as I was doing some test runs for the other problems. I also have a large cam so I thought the rough idle was normal and the stuttering and lean running was ignition. I did have an ignition problem too but that is another story.
this will check for a dead cylinder and a fuel problem if your spark is good. I had good spark to all cylinders.
next recheck your distributor for vacuum advance issues. (The other problem) You already have it warmed up from the first test, so disconnect the vacuum advance and plug it with a golf tee. Take it for a spin and see if it changes. The stock distributor has a plastic sleeve on the end of the arm for the vacuum advance that acts as a limiter. When the plastic fails and it falls apart you get too much advance. The fix is a brass sleeve you can get in a rebuild kit. You can get Lars paper s and it states the " all in" advance setting, the max mechanical advance you should have and the total vacuum advance
You could also not have enough mechanical advance or too much. When was the last time you timed your motor. I see you changed the plugs, wires etc..When you did this did you change the points and did you set the dwell correctly?
You could also have a bad fuel pump and your starving the engine under acceleration, you need a fuel pressure gauge inline and you can just blip the throttle and see if it goes up to 8 or 9 psi. I had this happen, the axle that was pressed into the casting that the rocker arm rotated on sheared out of its
little arms.
Last edited by Rescue Rogers; May 17, 2019 at 08:57 PM.
