More Carb Questions!!
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Elder User
Joined: Mar 2002
Posts: 609
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From: Watauga TEXAS
More Carb Questions!!
71 F100, 360, C6, 2wheel drive, 2bbl 500cfm Holley with #68 jets, 50cc accelerator pump
Truck runs great for the most part. But I notice a hesitation not off the line, but maybe 1/4 to 1/3 into the throttle. It only does it when you're driving around town and gradually accelerating and is hardly noticeable when floored.
The engine has 6000 miles on it. I've advanced and retarded the timing, richened and leaned the fuel, checked for vacuum leaks, tried switching the vacuum hoses on my vacuum advance (dual port), and everything ignition-wise (cap, rotor, wires, electronics) is in new condition. I can't think of anything else except for two more things. #1: I still have the water-heated carb spacer hooked up and #2: It almost feels as if the power valve is opening up late (possible?). The reason I say that is, if you put your foot on the brake, put it in gear, and gradually accelerate (holding the truck in place), and you gradually increase the throttle after it stumbles, there is a surge of power as if the power valve opens at that point. I don't know- maybe I'm pi$$ing in the wind.
Maybe some of you guys have had this problem- let me know
Joe
Truck runs great for the most part. But I notice a hesitation not off the line, but maybe 1/4 to 1/3 into the throttle. It only does it when you're driving around town and gradually accelerating and is hardly noticeable when floored.
The engine has 6000 miles on it. I've advanced and retarded the timing, richened and leaned the fuel, checked for vacuum leaks, tried switching the vacuum hoses on my vacuum advance (dual port), and everything ignition-wise (cap, rotor, wires, electronics) is in new condition. I can't think of anything else except for two more things. #1: I still have the water-heated carb spacer hooked up and #2: It almost feels as if the power valve is opening up late (possible?). The reason I say that is, if you put your foot on the brake, put it in gear, and gradually accelerate (holding the truck in place), and you gradually increase the throttle after it stumbles, there is a surge of power as if the power valve opens at that point. I don't know- maybe I'm pi$$ing in the wind.
Maybe some of you guys have had this problem- let me know
Joe
Laughing Gas
Joined: Oct 1999
Posts: 1,165
Likes: 3
From: central Alberta
More Carb Questions!!
There's a possibility your power valve may be blown, too. Unfortunately, the only way to know for sure is to pull off the bowl and jet body to see if the back side is wet. These valves do come in different vacuum ratings (accomplished by stiffer springs)
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Elder User
Joined: Mar 2002
Posts: 609
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From: Watauga TEXAS
More Carb Questions!!
Yeah, I checked it again and it's good. It was a 5.5 so I put an 8.5 in it. It still has that "weak spot" when you gradually accelerate.
I'm also thinking that it might have to do with the advance on the distributor. The distributor is in great shape. I took it apart and lubed all the friction points and made sure the mechanical advance was working. The diaphram for the vacuum is good and works like it should. Unfortunately I can't adjust it.
Maybe I need to go to a lighter spring for the weights. I'll try it to see if it makes a difference.
Any other suggestions would be greatly appreciated!!!
Joe
I'm also thinking that it might have to do with the advance on the distributor. The distributor is in great shape. I took it apart and lubed all the friction points and made sure the mechanical advance was working. The diaphram for the vacuum is good and works like it should. Unfortunately I can't adjust it.
Maybe I need to go to a lighter spring for the weights. I'll try it to see if it makes a difference.
Any other suggestions would be greatly appreciated!!!
Joe
