Start with the simple stuff first.
It lives, but running rough
Thread Starter
Drifting
Joined: Dec 2007
Posts: 1,309
Likes: 24
From: Coastal Georgia
C2 of the Year Finalist - Modified 2020
It lives, but running rough
I finally got the new motor in (see sig...not a new crate motor, but a freshly rebuilt 350) and after about a dozen attempts to get the distributor clocked correctly, got it fired. It fires right up and runs, and the timing is set and coming in completely at 36 degrees by 3000rpm. The problem is, it idles pretty rough, and I can feel a misfire or shudder randomly throughout the cycle. It feels like it fires really hard on one cylinder, but not every time throughout the cycle. I installed new plugs before firing the motor for the first time, and it has new plug wires, cap, rotor, etc. I have tried both a Holly 650 DP and an Edelbrock Performer 600 and both carbs have the same symptoms. If I give it some gas, it smooths out until about 1200 rpm, where it gets a pretty good vibration until about 2000rpm and then smooths out again and runs like a top.
I thought about changing the plugs again, thinking I may have fouled one or two up during break in (had a vacuum leak at the headlight nozzle on the intake and had a couple glowing headers). Could it be something this easy? I also worry that the balancer is off, but that wouldn't really explain the misfire. Help...
I thought about changing the plugs again, thinking I may have fouled one or two up during break in (had a vacuum leak at the headlight nozzle on the intake and had a couple glowing headers). Could it be something this easy? I also worry that the balancer is off, but that wouldn't really explain the misfire. Help...
Last edited by Quil; May 20, 2008 at 11:08 PM. Reason: ****
CF JASOC Member
Joined: Feb 2006
Posts: 8,040
Likes: 34
From: Downtown Annapolis, MD. The Future is where we all have to live. Let's not screw it up.
St. Jude Donor '08-'09-'10-'11
Thread Starter
Drifting
Joined: Dec 2007
Posts: 1,309
Likes: 24
From: Coastal Georgia
C2 of the Year Finalist - Modified 2020
OK, I'll check all the bolts for tightness and check the hoses. It acts the same all the time. I also bought a new set of plugs that I'm going to throw in, and I'll pull the valve covers and double check the rockers for tightness.
Burning Brakes
Joined: Apr 2007
Posts: 1,028
Likes: 1
From: SOUTH ELGIN IL
Spray some starter fluid around the base of the carb, etc while it's idling. If the idle goes up, you've found your leak.
You an also cup your hands over the carb, engine should die. If not, carb is pulling vaccuum from somewhere it shouldn't be.
You an also cup your hands over the carb, engine should die. If not, carb is pulling vaccuum from somewhere it shouldn't be.
Pro
Joined: Apr 2007
Posts: 736
Likes: 1
From: Chester VA
I usually just cap off all vacuum ports on the motor to check for leaks, vs. checking through the whole system. It won't pinpoint the leak, but you can narrow it down to a port if there is one. I once had a brand new vacuum cap that was split open connected to the carb, drove me nuts for a long time, was the last thing I expected to be wrong.
Thread Starter
Drifting
Joined: Dec 2007
Posts: 1,309
Likes: 24
From: Coastal Georgia
C2 of the Year Finalist - Modified 2020
I am an idiot. 3 and 4 plug wires were reversed...
Thanks for all the help, though...I did manage to find a few vacuum leaks as well, so it should be running really smooth now. 
Thanks for all the help, though...I did manage to find a few vacuum leaks as well, so it should be running really smooth now.
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Burning Brakes
Joined: Mar 2008
Posts: 1,038
Likes: 39
From: Denver, CO
St. Jude Donor '08-'09-'10
sad comment.... but one time i ran mine COMPLETELY backwards... and it ran too! it was like double backwards... wrong side labeled one.. and wrong way. (like clockwise vs. counter clockwise)
i still dont really know how it ran... but whatever
i still dont really know how it ran... but whatever