Dodge72
Odd one out
I cannot figure out for the life of me what is wrong with my carb (1970 Holley 1920) and/or fuel system. The symptoms: When I start up the car ('72 slant) it starts right up. It's not a very good start, the engine mumbles out a small idle for a second before dying unless I give it gas. When I hit the gas, as long as I put my foot on the gas, it runs very smoothly but if I let off, the idle drops straight down and dies. Seems to have an occasional misfire at about 15-1600 RPMs, smooth when revving. No struggle, just a very quick death. Once it warms up, it's a little harder to start, but still, refuses to idle. After adjusting the curb idle speed after it warmed up (or tried to), it did idle, but only at 1500 RPMs. Anything below, like when the fast idle cam goes down a notch, it begins to quickly suffer and turns off within 5 to 10 seconds. My dad actually drove it, and the car is quick to respond, no stumbling at acceleration, it's the idling below 1500 that it has troubles with. Fuel delivery issue confirmed because if I were to spray carb cleaner or such into the body at idle, RPMs increase and smooth. Total timing I checked at 1500 "idle" was 15-20* BTDC.
Things I have done: Tried to make adjustments on the carb. The curb idle screw goes all the way in and still does not idle. Adjusting the base idle does not help. Dizzy timing, while I have not fussed with it right now but before when I got my engine done, only delays starting up and running or refuses to start if I move it a tooth either direction. Recently, I have put in; new camshaft, new timing chain and gear set, new lifters, adjusted valve lash when it was warmed up, new condenser, new coil, adjusted spark plug gap to .035". Rebuilt the carburetor with kit from Mike's Carb.
Carburetor: When taking it apart, the expanding plug from on top of the idle tube and it just fell out, so I got a new one and pressed it in. I found carbon buildup in the idle tube, so I sprayed that out and cleaned it up before putting it back together. I did notice that the vacuum pulloff connected to the choke, when fully close, doesn't seem to activate the vacuum at all. I didn't know if it was such a minute thing I couldn't see, so I left it alone. The float, I checked, actually floats, no bubbles, and repels liquids quickly.
Could it be that I misadjusted the float? Or is it simple tuning, or maybe both? Or something else completely? This is my first real deep immersion in carburetors and I'm a novice at tuning and adjusting and could certainly use some help. I hope I gave enough info (maybe too much!)! Thanks!
Things I have done: Tried to make adjustments on the carb. The curb idle screw goes all the way in and still does not idle. Adjusting the base idle does not help. Dizzy timing, while I have not fussed with it right now but before when I got my engine done, only delays starting up and running or refuses to start if I move it a tooth either direction. Recently, I have put in; new camshaft, new timing chain and gear set, new lifters, adjusted valve lash when it was warmed up, new condenser, new coil, adjusted spark plug gap to .035". Rebuilt the carburetor with kit from Mike's Carb.
Carburetor: When taking it apart, the expanding plug from on top of the idle tube and it just fell out, so I got a new one and pressed it in. I found carbon buildup in the idle tube, so I sprayed that out and cleaned it up before putting it back together. I did notice that the vacuum pulloff connected to the choke, when fully close, doesn't seem to activate the vacuum at all. I didn't know if it was such a minute thing I couldn't see, so I left it alone. The float, I checked, actually floats, no bubbles, and repels liquids quickly.
Could it be that I misadjusted the float? Or is it simple tuning, or maybe both? Or something else completely? This is my first real deep immersion in carburetors and I'm a novice at tuning and adjusting and could certainly use some help. I hope I gave enough info (maybe too much!)! Thanks!
