Carb question

[intofx]

Is the tank vent open and working?

It's a good question but I don't know. Is there an easy way to check?



I picked up the car yesterday but it's still stumbling off the line at WOT. They put a larger (same size as my original) fuel pump on the car so at least I'm getting a steady and regulated 6psi of pressure. With the car hot and running I checked the level in the bowls and the secondaries (bottom of the glass) are lower than the primaries (half way). Shouldn't they be the same front to back?

Also, it looks like my alternator is weaker than it should be and isn't pulling it's weight with any accessories on. Could that be causing issues with the ignition that may present themselves as a fuel/carb problem?

Would it help if I posted a video of the stumble?

Thanks again, guys.

Matt

[Yoda4561]

Low voltage at the ignition can be a real problem. I assume by your issues you're running a 1 wire alternator, I suggest switching back to a 3 wire style, like a 12si or more modern cs130.

This article convinced me it was the way to go. I had all kinds of charging and voltage issues on a one wire alternator back when I had a 72 cutlass, at idle it could barely power the lights, and I'm pretty sure it was the cause of some of my off-idle stumbling issues.

http://www.madelectrical.com/electri...hreewire.shtml

[intofx]

Low voltage at the ignition can be a real problem. I assume by your issues you're running a 1 wire alternator, I suggest switching back to a 3 wire style, like a 12si or more modern cs130.

This article convinced me it was the way to go. I had all kinds of charging and voltage issues on a one wire alternator back when I had a 72 cutlass, at idle it could barely power the lights, and I'm pretty sure it was the cause of some of my off-idle stumbling issues.

http://www.madelectrical.com/electri...hreewire.shtml

You would be correct. 1 wire. Is it tough to rewire for 3 wire?

[intofx]

Low voltage at the ignition can be a real problem. I assume by your issues you're running a 1 wire alternator, I suggest switching back to a 3 wire style, like a 12si or more modern cs130.

This article convinced me it was the way to go. I had all kinds of charging and voltage issues on a one wire alternator back when I had a 72 cutlass, at idle it could barely power the lights, and I'm pretty sure it was the cause of some of my off-idle stumbling issues.

http://www.madelectrical.com/electri...hreewire.shtml

You would be correct. 1 wire. Is it tough to rewire for 3 wire?

[Tech @ BG]

It's a good question but I don't know. Is there an easy way to check?

I picked up the car yesterday but it's still stumbling off the line at WOT. They put a larger (same size as my original) fuel pump on the car so at least I'm getting a steady and regulated 6psi of pressure. With the car hot and running I checked the level in the bowls and the secondaries (bottom of the glass) are lower than the primaries (half way). Shouldn't they be the same front to back?

Also, it looks like my alternator is weaker than it should be and isn't pulling it's weight with any accessories on. Could that be causing issues with the ignition that may present themselves as a fuel/carb problem?

Would it help if I posted a video of the stumble?

Thanks again, guys.

Matt

As mentioned the low voltage will cause all kinds of tuning issues and should be corrected prior to trying to make any calibration changes to the carburetor.

In regards to the vent you'll need to locate it and then trace it back to the tank, make sure it is not pinched or collapsed and if it has a filter at the end make sure that is not stopped up.

[Yoda4561]

You would be correct. 1 wire. Is it tough to rewire for 3 wire?

Not at all, the DIY info is all on their website, you can find other diagrams and stuff googling 3 wire alternators. It's really not a complicated hookup procedure at all, you can probably do it in an hours time if you study the diagrams beforehand.

[intofx]

So, in the LA heat this weekend (100+) the car almost left me stranded because of vapor lock. I'm having a new shop look at running a new fuel line next week - then the alternator issues - then either a new carb or try to get this Demon going. The overwhelming majority of people I've spoken with, say ditch the Demon for a Holley HP. Any suggestions as to which one? I could have bought a Holley and a half for what I've spent trying to get this Demon to play nice. I'm so mad at the guy I bought this car from I could spit.

[RUSS68CAMARO]

Ditch the carb. I had a demon on a mildly build 350 and I could never get it to run right. I swore I would travel the earth telling of the junk I got from BG. The front fuel bowl sight glass o-ring was pinched, metal shavings in the aft fuel bowl and I bought on with the Easy Idle adjustment which never worked right. I called them and they said that was for built motors but no where in their advertisements does it say that. Trash It!!!!!!!!!!!!!!

[intofx]

Ditch the carb. I had a demon on a mildly build 350 and I could never get it to run right. I swore I would travel the earth telling of the junk I got from BG. The front fuel bowl sight glass o-ring was pinched, metal shavings in the aft fuel bowl and I bought on with the Easy Idle adjustment which never worked right. I called them and they said that was for built motors but no where in their advertisements does it say that. Trash It!!!!!!!!!!!!!!

Any suggestions which carb to buy for my 383?

Matt

[John Haley]

I have not had a bad Demon carb yet, but have found many other problems that will make you think you have a bad carb. The two most common are, Idle screws are set at about 3 turns out. The other is old rotted fuel line sucking air.

Turn your idle adjustment screws in until they stop. You will think they are in all the way, but they are not. At this point they are about 1 1/2 turns out. Leave them there, reset your idle and go drive it.

If you are still having vapor lock problems and droplets of fuel spitting from the over flow tubes, check for bad fuel line sucking air( usually the rubber one at the tank connecting to the metal line on the frame), also check to see if your fuel sock in the tank is plugged.

[intofx]

I've officially given up on the carb. I'm going to do what I should have done in the first place and have the car EFI-ed. All of the problem parts will be replaced and the fuel lines re run as a result. I just wish I had pulled the trigger before spending a pile of cash trying to fix this car one part at a time...

Matt