Hesitation going up hill.

[boostdtalon]

On my way home today, I ran into an issue with the truck hesitating going up a steep slope. I drive this slope every day on my way to and from work and have never had this issue on the hill. Truck did fine till about the halfway point of the hill and started acting like it was cutting out. Was so bad I had to take some side roads home as I could only drive around 15-25 mph. Once the truck got back on level ground, it ran just fine. Gas level was between 1/4 and a 1/2. Looked at the fuel filter I installed just before the carb and didn't see anything that would cause concern.

I've had this issue before but was never this bad. Normally it's a slight shudder and than it's back to being fine again.

Not sure where to check for a cause. So here's a quick run down on things that have been recently replaced or added to help me narrow this.

new plugs proper gapped
fuel pump and new fuel filter.
gas tanks were drained before i started driving the truck
air filter cleaned and re oiled (K&N)


Thinking maybe I need to replace my cap, rotor, and wires as those are old. It was converted to an HEI system.

 

[boostdtalon]

Well after talking with one of my co workers who is more knowledgeable about older V8's. He seems to think that my issue is my carb needs to be rebuilt. I know mine was rebuilt but it's been more than 10 years and with the truck sitting for that long. I'm fairly convinced he's correct. I have a friend that was going to give me a free holley that needs to be rebuilt. May try and get that soon and rebuild that till I can rebuild the quadrajet.

 

[MadOgre]

Yep sounds like your float and needle and seat are the issue. Don't throw away the quadjet im gonna post a thread on here about rebuilding them properly including new throttle bushings and properly sealing the fuel well plugs with threaded plugs.

A rebuild kit for what you need to get it back in usable shape is about $45-60. and some carb parts cleaner.

 

[boostdtalon]

I actually just watched a power block video where they rebuilt a quadrajet and did the same thing. I'm found a local retired guy that is clearing out his carburetor shop. Going to pick up a quadrajet from him. He quoted me $70-75 for the new one.

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[MadOgre]

That's a sweet deal get an electric choke as the newer 80'+ models with electric choke have added fuel bowl volume and a few other minor nice features.

 

[boostdtalon]

Yeah I'll see what he has when I go by. His listing states that he has various carbs from the 50's to the 80's. He said he would match up what I had and make sure I was taken care of. An electric choke would definitely be a big plus to have.

 

[MadOgre]

Well if you have the thermostatic choke and you went with electric you would have to block off the intake port for the heater element and run a positive 12 volt to the carb. I think that's about the only real difference.

If you have the divorced choke. Then its just a matter of running the 12 volts.

I have a 77 divorced choke that im running until I get my 85 electric choke one done. Its still a good carb.

 

[MadOgre]

the vacuum ports are a little different but really not much of an issue.

 

[boostdtalon]

I think its a thermostatic choke, but I could be wrong. I'm still learning about these trucks.

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[MadOgre]

The thermostatic choke will kinda look like the electric but with no wires and there will be rubber hoses that come out front and back and go into the intake manifold.

The divorced choke has a wound spring mounted to the manifold with a little cover over it and a little linkage arm that attaches it to carb.

 

[Driver4r]

Pshh, who needs choke? Just wire it open XD.

 

[boostdtalon]

Ok its a divorced choke.

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[HotRodPC]

Well if you have the thermostatic choke and you went with electric you would have to block off the intake port for the heater element and run a positive 12 volt to the carb. I think that's about the only real difference.
.

I see where you're going here but, blocking off the water for the intake heater would be optional. It will run just fine with hot water intake warmer. There are several models that don't even use the hot water choke and they still have the hot water crossover warmer. Partially due to emissions. The warmer intake helps the fuel vaporize and burn more efficiently. For a daily driver, that's all fine and dandy. But as we all know, Cold Fuel is better for performance or racing.

Ideally I'd block it off too, but for the purpose of him having to take his intake off just to block it off... If it's a daily driver and looking more for dependability than a few horsepower, I just think I'd skip that step of blocking it off. Lots of work and risk of not getting it back together properly just for a minor feature. JMO

 

[MadOgre]

I see where you're going here but, blocking off the water for the intake heater would be optional. It will run just fine with hot water intake warmer. There are several models that don't even use the hot water choke and they still have the hot water crossover warmer. Partially due to emissions. The warmer intake helps the fuel vaporize and burn more efficiently. For a daily driver, that's all fine and dandy. But as we all know, Cold Fuel is better for performance or racing.

Ideally I'd block it off too, but for the purpose of him having to take his intake off just to block it off... If it's a daily driver and looking more for dependability than a few horsepower, I just think I'd skip that step of blocking it off. Lots of work and risk of not getting it back together properly just for a minor feature. JMO

I did not know that there was a coolant warmed thermostatic choke. I thought they all used the exhaust cross over ? which is what I was referring to. Even if it was hot water operated the actual choke heater element would be easy to block off if you want as it would not have coolant inside it. So just leave the element in place and forget about it.

Actually I guess that would work for either scenario.

 

[HotRodPC]

I did not know that there was a coolant warmed thermostatic choke. I thought they all used the exhaust cross over ? which is what I was referring to. Even if it was hot water operated the actual choke heater element would be easy to block off if you want as it would not have coolant inside it. So just leave the element in place and forget about it.

Actually I guess that would work for either scenario.

I may even be thinking of something else than you are. I do know there are several different types of choke. I was just saying, he don't need to take the intake off to block off the crossover if he didn't want to go through all that just for a choke conversion.
Some of the older ones even used a choke stove that bolted to the intake and that one pretty much just detected the radiant heat off the top of the intake. IMO, one of the most effective choke systems. They just didn't work real well once the choke butterfly shaft starting getting gummed up and taking more effort to close to the butterfly or have it hang closed when the thermostatic spring was trying to pull the butterfly off, or the butterfly would pull off and the hi idle cam to the idle adjustment screw would hang up and not let the idle come back down. I think the most complicated thing on a Carb is the choke/hi idle mechanisms. Always seem to have issues getting them to work right. I've just not have real good luck with auto choke set ups. Manual choke set ups have never let me down though.