Author Topic: 78 k20 350 bogging under a load.  (Read 1849 times)

Offline Binder307

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78 k20 350 bogging under a load.
« on: March 31, 2013, 07:23:26 PM »
I just bought a 78 k20 Scottsdale with a 350. It has an Eddelbrock 650 carb and a performance intake. The fuel tank had water in it so I drained the tank and filled it up with fresh gas and dumped a bottle of fuel additive to dry any water left in the lines and started the 4 hour drive back to my house. I have used two tanks of gas on the drive back to my house so I am sure the water is out of the system now. The real issue I am having is when I go to really step on the gas or hit a hill. Whenever I would come to a hill I would have to let off the throttle and slow down to keep it from backfiring and popping. Halfway home I got out and adjusted the automatic choke to try and get it to run better and this helped with backfiring some but it still wouldn't be able to climb a hill. If I kept my foot just barely on the gas and it seems to run fine. It idles fine for the most part. The guy I bought it from hadn't driven it for almost a year so I am planing on getting a rebuild kit for the carb but I am not sure that is the real problem I am having. I was wondering if this might be some kind of timing issue or something like. I would love any thoughts you guys might have on the matter or some places to start checking. Thanks in advance.

Offline bake74

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Re: 78 k20 350 bogging under a load.
« Reply #1 on: March 31, 2013, 07:28:49 PM »
     Welcome to the site from California.
You are on the right track.  Timing and a tune-up would be the first thing to do and re drive to test.  I am just guessing by the information you have provided, but the carb will need to be rebuilt, the spark plugs more than likely will need to be replaced/cleaned if possible, and timing set.
#1: The easiest and most obvious solution to any problem is 99% of the time correct.
#2: There is no such thing as impossible, it just takes longer.
  74 k10, 77k10    Tom

Offline Binder307

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Re: 78 k20 350 bogging under a load.
« Reply #2 on: March 31, 2013, 07:34:16 PM »
Well I wasn't complete sure if that was a good starting place and didn't want to dive into it and have it not be related so thanks for the comment. And since  there is no time like the pressent I best get started on that and will let you know what happens after that.

Offline Binder307

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Re: 78 k20 350 bogging under a load.
« Reply #3 on: April 03, 2013, 02:46:44 PM »
I took apart the carb and sure enough it had a bunch of dirt and crud in it. The floats were really bent out of shape so I got everything back to were it should be. Some where along the way I lost a linkage rod to the throttle, and just my luck I no parts stores had any so I had to order it. I went ahead and looked into why I was getting dirt and water in the fuel. The O ring on the tank was bad so I dropped the tank and had to order a new O ring kit. I also washed out the tank and cleaned everything up so when I finally get to fire it up there shouldn't be any problems. This truck only had one tank on the passenger side even though it has two doors. I have read and talked to people who have had tons of problems with the tank switching unit so I assume that someone along the way just took the drivers side tank out. I am thinking I will just move the passenger side tank over to the driver side for convince. I should be able to just longer fule lines and run them along one of the frame suports over to the other side right? Any little tricks or words of caution before I put it all together?