Spitting and sputtering.

[blaylock6502]

Hey guys. I have a 74 CJ5 with a AMC 258 i6 / 4.2l . It has a hedman header and an edelbrock intake. I thought the carb was factory and the butterflies were loose so I ordered a factory replacement. After getting it I found what was on it was a carter two barrel. I got an adapter and put the one barrel on. I set the timing made sure vacuum advance was working and set carb to spec. Now under a heavy load accelerating it falls on its face and spits and sputters. After it develops enough rpm it breaks through like its starving for fuel. Do I need bigger jets for the header and adapter?

 

[Torxhead]

It kinda sounds like you had this issue before you swapped carbs. Did the carb change make any difference? It could be an ignition problem or the carb is not set up correctly. Sometimes the ignition control module can give you fits. Headers will not make the engine lean out that much, make sure you have no vacumn leaks also. An accelerator pump out of adjustment on the carb can cause these issues, but will improve after it gets going.

 

[IOPort51]

you replaced a 2 bbl with a 1 bbl??

 

[blaylock6502]

Does anyone know how the vacuum advance is supposed to be set up? Full manifold vacuum or on acceleration?

 

[mtnwhlr]

The vacuum advance is hooked up to ported vacuum.

 

[Torxhead]

You want ported vacumn, which is where the vacumn increases as the throttle is opened up. It will have to come from a carb mounted outlet.

 

[1986cj7]

Hey guys. I have a 74 CJ5 with a AMC 258 i6 / 4.2l . It has a hedman header and an edelbrock intake. I thought the carb was factory and the butterflies were loose so I ordered a factory replacement. After getting it I found what was on it was a carter two barrel. I got an adapter and put the one barrel on. I set the timing made sure vacuum advance was working and set carb to spec. Now under a heavy load accelerating it falls on its face and spits and sputters. After it develops enough rpm it breaks through like its starving for fuel. Do I need bigger jets for the header and adapter?

You may want to check your float adjustment, it could be to low causing it to run out of fuel.

 

[mtnwhlr]

It could be you went from a 2bbl to a 1bbl and it is not getting the fuel it needs.

 

[blaylock6502]

Its a 74 and it came from the factory with a 1 barrel and somewhere along the way someone put an edelbrock intake from an eighty's model on it with a carter two barrel from an eighty's model on it. Im a technician for general motors and it doesn't seem to have a cam of any significance in it and it seems like its worsening. And im twenty eight so being a technician doesn't mean much because other that adjusting a carb and setting points this thing may as well be an alien spacecraft. Im used to fuel injection and electronic ignition

 

[IOPort51]

OK, here is whats wrong with the "thats the way it was built" theory. The most obvious thing is the tires are way bigger than it came with. The entire reason I changed from 1 bbl to 2 bbl was so I could run 31s and be able to climb the driveway. I guess what I am saying is even if you get the 1 bbl to work at max efficiency I think you will find it underwhelming.

Fuel injection!! that is the goal! go for it!

Just to confuse things a bit more, is this the original Head?? exhaust manifold??

Its a 74 and it came from the factory with a 1 barrel and somewhere along the way someone put an edelbrock intake from an eighty's model on it with a carter two barrel from an eighty's model on it. Im a technician for general motors and it doesn't seem to have a cam of any significance in it and it seems like its worsening. And im twenty eight so being a technician doesn't mean much because other that adjusting a carb and setting points this thing may as well be an alien spacecraft. Im used to fuel injection and electronic ignition

 

[blaylock6502]

It is the original head I know this because I've tried to find a valve cover that doesn't leak(Haha) and the only thing I can find is 250 bucks and its a hedman header. I thought maybe it would need to be rejetted for the header but I was assured that was not the case. The more I drive it the more it seems like ignition and it's getting worse every day. Im really not concerned about power as I just use it for cruising backroads

 

[IOPort51]

If your happy than we are happy.

I must warn you that one of these days the long awaited and anticipated MC2100 "sticky" that Elwood is working so feverishly on will be posted. Having seen the previews I predict that there will not be an AMC l6 owner in the free world that will not be looking for a ford 2 bbl to build for their very own.

It may be a good idea to frequent the Pick Your Parts looking for a core before they all evaporate.

It is the original head I know this because I've tried to find a valve cover that doesn't leak(Haha) and the only thing I can find is 250 bucks and its a hedman header. I thought maybe it would need to be rejetted for the header but I was assured that was not the case. The more I drive it the more it seems like ignition and it's getting worse every day. Im really not concerned about power as I just use it for cruising backroads

 

[blaylock6502]

Ok do im leaning towards putting my 2681 carter two barrel back on but I will rebuild it first. After looking it over the rod for the throttle plates has a little slop in it where it passes through the body of the carb. Is there any repair possible here or is one even needed?

 

[IOPort51]

We generally refer to the carter 2 bbl as the BBD. I know it's potato,potato but just saying.

I think you can bush the BBD, or any other carb for that matter. The hard part would be drilling the throttle body and I would think a machine shop would be involved with that. If the BBD was an endangered species It may be worth the expense but it isn't.

With out seeing it in person I can not gauge what "a little slop" is. Do you think it is enough to cause a vacuum leak?