Surging at low rpm

[dmwhiteoak]

I have been working on this car for a month and now I'm at the carburetor. At low rpm(below 3000) , it surges pretty bad.
I don't know which carburetor it is, but it has two set screws on the left side. One is for idle adjustment and one for fuel /air mixture. It seems to run better with fuel/air mixture screw out quiet a ways. I was wondering if there was a base line to start at like maybe two turns out or something. Maybe this not the problem, I don't know. Maybe someone has had this problem before. This appears to be my last obsticle. It does have a new crane electronic ignition that was installed by the previous owner. This could possibly be the problem. Anyone have any ideas?

Thanks Dennis

[124JOE]

hey there
i think you have a vacume problem
my crain cams fireball 3000 only ever had one problem
a wire shorted out at the dizzy
and that was an easy fix
these things dont have problems
if it works at all its ok.but check your wires just to be sure.joe

[dmwhiteoak]

thanks Joe, I did find a bare wire where the cap was installed over the wire. Fixed that but still surging. I think maybe my brake booster is leaking because I hear a hiss until I apply the brake, then the eingine idles up. does this sound repairable or need to replace? when the outside temp drops below 100 I will plug the hose to the booster and see what happens.I have thought that it was sucking air from somewhere.
Dennis

[zappi]

A branke booster has a rubber diaphram that creates the vaccum. If at some point the Master Cylinder leaked into the booster and was never noticed, that would be enough to damage the diaphram given the age of the vehicle. Check for missing paint under the Master Cylinder as brake oil is great for removing paint.

I hope this helps.

[majicwrench]

Most of these carbs are forever plugging the low speed jet. Simple fix.
Booster, you have the right idea, just plug it off and see if it helps.
And yes, idle mix screw on most of these should be about 2 turns out, there is a lot of info on this.
Keith

[So Cal Mark]

the booster shouldn't hiss without depressing the pedal. A constant hiss would indicate a leak in the hose to the booster

[dmwhiteoak]

Well , I plugged the brake booster and it ran a little better. increased idle 300 rpm's. I found what was leaking was where the hose connects to the booster . Not a good seal on the plastic piece where it snaps into booster. Will work on that. Fixed a couple of other leaks and went for a drive . On the way back home , just cruising , the left rear wheel come off. What a ride. No damage other than 1 missing and one stripped lug bolt . Walked 1/2 mile back down the road and found 3 . So take some advice , when you buy a used car check the luggs. After checking all the others , they were ALL loose.

Dennis

[sptcoupe]

Wow! Count your lucky stars! A friend of mine lost a wheel (had a flat repaired at a shop and they didn't tighten down the lug nuts) at abbout 45 MPH. Major damage to the sheet metal around the wheel well, torn brake line, and bent tie rods. Good news was he felt a wobble just before it came off and had slowed to 45 from about 65!

[dmwhiteoak]

I cha'nged the base gasket on the caeb today because it was sucking air at the base . I dont think that fixed my problem because it still won't idle smoothe . I didn't get to drive it because im doing some front end work. when I sprayed carb cleaner around the carb it idled up in a few places. around the accelerator pump it idled pretty high. Is this normal.

[124JOE]

most everything is fixable the main question would be did it ilde up around the shafts where the butterflys pivot
and the choke plate shaft.--if not real good ,buy a rebuild kit.clean your jets,check all the vacume lines.joe

[dmwhiteoak]

most everything is fixable the main question would be did it ilde up around the shafts where the butterflys pivot
and the choke plate shaft.--if not real good ,buy a rebuild kit.clean your jets,check all the vacume lines.joe

Thanks Joe, thats will be my next move. Took it out for a drive last night and it ran a little better but not right. I can't seem to get it to where its not burning rich. I did clean all the jets that i saw but not the two inside the carb looking from the top. didn't see those until after i had it back on.The wife is on me to get it right and fast. She loves this car but doesn't understand that its not hers. Its mine.

[majicwrench]

Did you clean the idle/low speed jet?? That is the one that matters.

[dmwhiteoak]

I can't say for sure if I cleaned the idle/lowspeed jet but all that I saw. I have a kit ordered and will rebuild it saturday. It continues to run too rich no matter how the fuel/air screw is set. maybe this will fix the problem.

[124JOE]

theres 2 more jets in the bowl

can someone tell us witch jets are witch?joe

[majicwrench]

Behind this brass screw (my pen is pointing at it) is the idle/low speed jet