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67 c20 runs rough

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Old July 13th, 2018, 9:06 PM
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ok so hereís the deal I bought a 67 c20 for $400 off of a guy at my church. Iím 14 and the guy likes me so thatís why I got such a good deal. I got the truck home and did lots of work and got it running like a champion! Started right up ran good, plenty of power....... Iíve gone through several tanks of gas. But just the other day it was oddly cold for July and Otis, the name of my truck didnít like that at all..... so lately itís gotten warm again but my truck is starting awful, running on 2 or 3 cylinders and backfiring and just being a jerk to me.... so I THOROUGHLY CLEANED THE CARBURETOR and got six me ngk spark plugs, sanded points, rotor, and all the little tabs in the distributor, and it still runs awful. However once it gets hot, around running temperature it starts to clear out. Itís a 292. Any help would be nice. Please donít say ďjust let it warm upĒ because it used to run perfect all the time this truck is my pride and joy and I donít eat on it

Last edited by Leland drives 1967 Chevy c20; July 13th, 2018 at 9:09 PM.
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Old July 13th, 2018, 9:10 PM
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Originally Posted by Leland drives 1967 Chevy c20 View Post




ok so hereís the deal I bought a 67 c20 for $400 off of a guy at my church. Iím 14 and the guy likes me so thatís why I got such a good deal. I got the truck home and did lots of work and got it running like a champion! Started right up ran good, plenty of power....... Iíve gone through several tanks of gas. But just the other day it was oddly cold for July and Otis, the name of my truck didnít like that at all..... so lately itís gotten warm again but my truck is starting awful, running on 2 or 3 cylinders and backfiring and just being a jerk to me.... so I THOROUGHLY CLEANED THE CARBURETOR and got six me ngk spark plugs, sanded points, rotor, and all the little tabs in the distributor, and it still runs awful. However once it gets hot, around running temperature it starts to clear out. Itís a 292. Any help would be nice. Please donít say ďjust let it warm upĒ because it used to run perfect all the time this truck is my pride and joy and I donít eat on it
I donít beat on it, stupid auto correct
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Old July 14th, 2018, 3:24 AM
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Originally Posted by Leland drives 1967 Chevy c20 View Post

I don’t beat on it, stupid auto correct
Not bad for $400 bucks. The 292 CI or 4.8 liter was a solid motor. Might be your ignition system. I'd check the rotor and cap first. Might be a bad coil or wires.
I would also check the distributor out thoroughly. Don't forget to check to see if the vacuum advance cannister diaphram isnt blown out too. She will burn more gas if its
not working.

And of course, don't forget to grease the muffler bearings!!!!
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^

Just kidding you about that!! BTW, is that a Three On the Tree 3 speed tranny?

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Old July 14th, 2018, 6:13 AM
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Thanks for the reply, I bought a new coil when I first got it running. And I donít feel like itís ignition because when it gets hot it runs perfect. Itís just so odd. And it never fails to run perfect after getting hot. And he fuel pump has plenty of power so powerful it blew a 2 liter off. Also if there was such a thing as muffler bearings, I wouldnít need to grease them it has about 4ft of exhaust....... which isnít intentional but the old muffler was so rust it just was hanging so I ripped it off. And surprising it way quieter than I thought. And hopefully within the next year Iíll have a 350 to put in. So I want the 292 to run perfect before I put it on a shelf. And btw it has a 4 on the floor
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Old July 14th, 2018, 6:50 AM
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Make sure the choke is working correctly. You might also want to rebuild the carb.
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Old July 14th, 2018, 8:21 AM
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Originally Posted by Leland drives 1967 Chevy c20 View Post
Thanks for the reply, I bought a new coil when I first got it running. And I donít feel like itís ignition because when it gets hot it runs perfect. Itís just so odd. And it never fails to run perfect after getting hot. And he fuel pump has plenty of power so powerful it blew a 2 liter off. Also if there was such a thing as muffler bearings, I wouldnít need to grease them it has about 4ft of exhaust....... which isnít intentional but the old muffler was so rust it just was hanging so I ripped it off. And surprising it way quieter than I thought. And hopefully within the next year Iíll have a 350 to put in. So I want the 292 to run perfect before I put it on a shelf. And btw it has a 4 on the floor
The four speed is the best transmission for an old 3/4 ton pickup, and you have a granny low-gear too. The three speed was basically a car transmission, and all the linkages go south on them soon enough.

OldChevy is correct about the choke. Those were a real b***h. I'd rebuild the 1 barrel Rochester carb. Those old motors were not meant to be used with anything but leaded gasoline, and the ethanol in most gasolines now tends to eat up the seals, O-rings and gaskets. I found a rebuild kit for the C-20 carb online here:

Rochester B BC BV Carburetor Repair Kit K1141

You might be able to find a vid on youtube about rebuilding the carb. I used to soak the housing down overnight and use an air-hose to blow out all the passages. You might have a bad accellerator pump too. Some carb maunufacturers used a leather piston seal, but I think the new carb kits use Viton piston seals.
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Old July 14th, 2018, 5:29 PM
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Originally Posted by oilcanhenry View Post
The four speed is the best transmission for an old 3/4 ton pickup, and you have a granny low-gear too. The three speed was basically a car transmission, and all the linkages go south on them soon enough.

OldChevy is correct about the choke. Those were a real b***h. I'd rebuild the 1 barrel Rochester carb. Those old motors were not meant to be used with anything but leaded gasoline, and the ethanol in most gasolines now tends to eat up the seals, O-rings and gaskets. I found a rebuild kit for the C-20 carb online here:

Rochester B BC BV Carburetor Repair Kit K1141

You might be able to find a vid on youtube about rebuilding the carb. I used to soak the housing down overnight and use an air-hose to blow out all the passages. You might have a bad accellerator pump too. Some carb maunufacturers used a leather piston seal, but I think the new carb kits use Viton piston seals.
thanks, any idea where I can get OEM rebuild kit?
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Old July 14th, 2018, 9:03 PM
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Is this a single barrell carb? If it as gm you can get the number off the carb body that will help in getting a kit, it could be also a Holley either way. I also agree with carb issue.
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Old July 14th, 2018, 9:05 PM
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Old July 15th, 2018, 4:44 AM
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Originally Posted by Leland drives 1967 Chevy c20 View Post

thanks, any idea where I can get OEM rebuild kit?
You cant find an OEM Rochester carb rebuild kit anymore, but these carburetor kit links below all claim that they will fit your Rochester 1 barrel Model B carburetor. Should be an aluminum tag that is on one of the float bowl screws with the exact part identification number of the carburetor:

https://www.napaonline.com/en/p/CRB25194A

https://www.oreillyauto.com/detail/b...etor+Kit&pos=0

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