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Old 12-31-2012, 07:56 PM
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4 of 8 cylinders working on sbc350

On Friday my car was running fine. So sat morning I go to start it and it would not stay on and throw smoke I checked my spark plugs and they where black(smelled like gas) so I figured it was running to rich so I took the CARB to get rebuilt. The car was shaking after the rebuilt so I changed the spark plugs on it and the shaking stopeed but now 4 of my 8 cylinders are not working (2 on each side). This I noticed by pulling the wire from the distributor and the cars idle wont change on 4 and on the working ones u can notice the difference in the idle. What can this be. I have a sbc350 with edelbrock intake, 4 barrel holley carb, street fire distributor, street fire wires. PLEASE HELP I'M LOST I NEVER DELT WITH THIS PROBLEM AND NEVER HEARD OF ANYONE TALKING ABOUT THIS ISSUE!!!THANK YOU IN ADVANCE!
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Old 12-31-2012, 09:26 PM
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Have you rechecked the plugs since the 4 of 8 started to misfire? I would start with simple things like making sure all plugs are getting fire from the distributor. Did you adjust the carb after reinstall? Have your checked timing? Did anything happen the last time it was running right (backfire, misfiring, got gas at an unusual location ETC)? Just a few ideas to get you started, hopefully someone more knowledgable will jump in and help you out some. Good luck and Happy New Year
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Old 12-31-2012, 10:34 PM
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I suggest on the cylinders it's not firing on do a spark test on those spark plug wires and see if they are in fact firing. If they're not somethings gone wrong in the ignition system. Keep in mind ignition problems often diagnose the same as fuel problems. Also need to know what year vehicle, what's the spark timing set at and what's the fuel pressure?
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Old 12-31-2012, 11:04 PM
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Everything was fine until saturday. Well the car is an 81 el camino. They told me to get new wires that the wires might be bad so i'm going to do that. You guys think this might help?
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Old 12-31-2012, 11:11 PM
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What would be the correct way to adjust the carb it's a holley 4 barrel. The guy at the shop told me that it was going to be that way till it burned off the excess in the plugs but i want to try to do it myself since i know my car. For this reason i changed them. The shaking stopped but the now i'm having the issue with the cylinders. I may add that i tried running it and the knobs that control the fuel and air mixture both where shut and as soon as i gave them about a half of a turn the car would want to shut off and that got me thinking kus it wasn't that way before can it be that?
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Old 12-31-2012, 11:13 PM
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@doublevision how can I do that spark test you are talking about?
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Old 12-31-2012, 11:41 PM
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A Few things to check.

I would start with the cap and rotor. Make the cap and rotor has no burnt terminals. If you have a meter you ohm the wires to check they are ok. Did you hear any noise coming from the engine (ticking etc.?) If the wires are good I would consider pulling the valve covers and making sure a rocker (s) did not back off. This happened to me once and killed 2 plugs.

The idle screw on the side of the carb should be set 1 1/2 turns out as a baseline and fuel press 5-7 lbs.
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Old 01-01-2013, 05:47 AM
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First of all the guy at the shop who is wanting to spend you money on what " might be" doesn't seem very competent. I don't spend my customers money on something until I know it's the problem. Since all of this missing got worse after you changed the plugs, double check the wires to make sure you don't have any of them crossed. Also to check the wires, most auto parts places have a light that goes between the plug and wire. Star the engine it the lights is flashing their is spark to the plug as it will flash everytime te plug wire sparks. They are usually pretty cheap you could get by with only one and move it from wire to wire
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Old 01-01-2013, 06:31 AM
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If they are the back 2 plugs on both sides of the engine the problem is the secondary float level on the back two barrels of the carb., if it's the front 2 plugs on each side it's the primary float level. The needle and seat valve is likely stuck open allowing fuel to drip into the manifold, flooding the 4 cylinders. My Holley did the same thing last year, which is fairly common on Holleys.

Take off the air cleaner and look into the carb., if you see fuel dripping in the back two barrels, or the front two barrels you have identified the problem. Here are some video clips I posted showing the problem.


Some guys will tap on the rear adjusting nut to see if that will pop it loose. Here is an excellent Holley video on Fuel Level & Float Adjustment. Go to about the 3:00 minute mark.

And here is a video showing removal of the needle and seat valve.

Hope that helps and good luck to you!

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Old 01-01-2013, 11:50 AM
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On the passenger side it's the 2 & 3 , on the driver side it's the 1 & 4.
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Old 01-01-2013, 01:24 PM
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I had the same problem with a 396. Chevy engines are numbered "1-3-5-7" on drivers side and "2-4-6-8" on pass side. On a dual plane intake if you follow the air intake runners, 1,4,6,7 use half of the carb and 2,3,5,8 use the other half. I pulled the Holley carb and found junk in one of the metering blocks. Rebuilt carb, fired her up and had all cylinders running about the same temp. I used a infrared temp gun on the header pipe at the head.I you don't have a IF gun, take a water bottle cap of water and dump it on the header tube, if it boils off fast that cyl in working, if it kinda runs off that cyl is not working. This will work on cast manifold as well but not so evident. Yesterday a 350 had a intermittent miss, found one cylinder cold replaced wire no more miss. These infrared temp guns are great. I would look into it might have to return that "rebuilt" carb for another try.Just something else to think about. good luck
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Old 01-02-2013, 11:32 AM
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Quote:
Originally Posted by sirron View Post
i had the same problem with a 396. Chevy engines are numbered "1-3-5-7" on drivers side and "2-4-6-8" on pass side. On a dual plane intake if you follow the air intake runners, 1,4,6,7 use half of the carb and 2,3,5,8 use the other half. I pulled the holley carb and found junk in one of the metering blocks. Rebuilt carb, fired her up and had all cylinders running about the same temp. I used a infrared temp gun on the header pipe at the head.i you don't have a if gun, take a water bottle cap of water and dump it on the header tube, if it boils off fast that cyl in working, if it kinda runs off that cyl is not working. This will work on cast manifold as well but not so evident. Yesterday a 350 had a intermittent miss, found one cylinder cold replaced wire no more miss. These infrared temp guns are great. I would look into it might have to return that "rebuilt" carb for another try.just something else to think about. Good luck
@sirron....well now that u point that out then it will be 1,4,6,7 that are not working properly. I should go to the carb shop once again and tell them that those cylinders are not working. What is it that they need to fix on this exactly so i can mention it to them?
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