In the photos i dont see the thick base gasket. If this is the case,that is your problem.
high Idle 318
- Thread starter Dakota R Keck
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Then your fast idle cam is NOT free to rotate and you need to address that first.
What is stopping it from rotating? if you unscrew the large diameter screw that the normal idle screw stops on a 1/4 turn does the fast idle cam rotate freely?
I disagree ( but I see where you were going), I do not have the thick base gasket and my car starts and runs fine even in COLD Colorado weather. two pumps on the gas after a week of sitting and it starts right up and idles fine at fast idle. then after a few minutes everything warms up and it idles at normal idle.
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Been there. Choke stat does not pull enough. My 80 powwr wagon has the identical choke thermostat, i left out the thick insulator and had a high idle problem. Drove me nuts, rebuilt my carb,tried a new rebuilt and same problem.
Vacuum break opens plate +/- 1/4” and stat takes over after that.
Sometimes it got hot enough to pull it off.
Its been 15 years since i opened carb,i recall there was also something with the accellerator
Pump or power valve hanging up at one time or another.
I have had that truck nearly 30 years, for the most part carb has been trouble free.
Vacuum break opens plate +/- 1/4” and stat takes over after that.
Sometimes it got hot enough to pull it off.
Its been 15 years since i opened carb,i recall there was also something with the accellerator
Pump or power valve hanging up at one time or another.
I have had that truck nearly 30 years, for the most part carb has been trouble free.
A carburetor kit is about $30 for a good one with the large instruction sheets. I would go ahead and buy one and a couple of cans of carburetor cleaner. If that front stud nut is the handiwork of who rebuilt it, it’s time to start over. This will help you familiarize yourself with it before starting.
These are very simple carburetors, it’s a good one to learn with.
These are very simple carburetors, it’s a good one to learn with.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Don't forget that the principal player in choke operation is the heat crossover under the carb..... which may have to be cleaned out several times on a teener as it accumulates mileage. This system includes the heat-riser flapper in the exhaust manifold and it's bi-metallic spring.
Also, as to the fast idle cam, the linkrod is usually set so that the fast idle screw cannot get onto the highest step, but rather, only rotates to the second highest step. I have had to many times, remove the fast idle cam and polish both the pivot boss and the inner diameter if the hole in the cam. In some stubborn instances I have had to ziptie a counterweight onto the linkrod. IMO, the factory did not provide enough counterweight on that model.
Also; on that model, they do have a lot of throttle opening at idle, so the curb-idle screw,to me, looks about right. I think this is partly due to the retarded idle-timing of 5* IIRC. But if the PCV circuit is clogged, then someone would screw in that curb-idle screw to get the extra air, that the PCV is failing to supply.The PCV is your idle-air bypass and is a principal player in establishing the Transfer-slot sync.
Another player is the float level. So if the idle-timing and T-slot sync are correctly set; and all the other systems are correctly functioning, and your idle speed still is not right, then it may be that the float-level is not correct. However, the rpm difference between correct float level and not correct is not likely to exceed 75rpm (I'm guessing).
With a carburetor, almost all errors in adjustments, except throttle opening, result in lower than normal idle-rpm; Jus saying.
Your choke is turned off by two things; 1) the electric choke heater, which sometimes goes thru a controller; and 2) by the heat crossover under the carb.
The controller is a small device about 1x1.75, usually screwed to the intake somewhere close to the coil. It will have two wires hooked to it; a blue one that gets it's power from the same place the coil does, namely the ignition switch thru the #1 splice; and the other is a short , usually cloth-covered,jumper that is directly attached to the choke element.
This device is just a bi-metallic spring timer, that usually shuts the choke off after 2 to 3 minutes on a cold engine. Their job is to prevent the choke heater from draining your battery if the cold engine should stall, and to increase the life of the choke heater, not necessarily in that order,lol. They are not known for their stellar performance.
But in your case it appears that all you fast-idle problem is in the sticking cam, probably, maybe..
Also, as to the fast idle cam, the linkrod is usually set so that the fast idle screw cannot get onto the highest step, but rather, only rotates to the second highest step. I have had to many times, remove the fast idle cam and polish both the pivot boss and the inner diameter if the hole in the cam. In some stubborn instances I have had to ziptie a counterweight onto the linkrod. IMO, the factory did not provide enough counterweight on that model.
Also; on that model, they do have a lot of throttle opening at idle, so the curb-idle screw,to me, looks about right. I think this is partly due to the retarded idle-timing of 5* IIRC. But if the PCV circuit is clogged, then someone would screw in that curb-idle screw to get the extra air, that the PCV is failing to supply.The PCV is your idle-air bypass and is a principal player in establishing the Transfer-slot sync.
Another player is the float level. So if the idle-timing and T-slot sync are correctly set; and all the other systems are correctly functioning, and your idle speed still is not right, then it may be that the float-level is not correct. However, the rpm difference between correct float level and not correct is not likely to exceed 75rpm (I'm guessing).
With a carburetor, almost all errors in adjustments, except throttle opening, result in lower than normal idle-rpm; Jus saying.
Your choke is turned off by two things; 1) the electric choke heater, which sometimes goes thru a controller; and 2) by the heat crossover under the carb.
The controller is a small device about 1x1.75, usually screwed to the intake somewhere close to the coil. It will have two wires hooked to it; a blue one that gets it's power from the same place the coil does, namely the ignition switch thru the #1 splice; and the other is a short , usually cloth-covered,jumper that is directly attached to the choke element.
This device is just a bi-metallic spring timer, that usually shuts the choke off after 2 to 3 minutes on a cold engine. Their job is to prevent the choke heater from draining your battery if the cold engine should stall, and to increase the life of the choke heater, not necessarily in that order,lol. They are not known for their stellar performance.
But in your case it appears that all you fast-idle problem is in the sticking cam, probably, maybe..
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Manual says set high idle on 2nd highest step.
Good point on counterweight mass being light, a strategically placed hole drilled through with a #6 machine screw from the back works well with a couple of washers and nuts for extra weight, too.
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looking at both carbs in post #6 and the carb in post #11 there is a huge difference in the amount the idle screws are turned. Mine (post #6) works great OP doesn't. Also OP stated in post #15 that is fast idle cam does not return to full clockwise on its own which is what OP was eluding to in his original posts.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Yours looks right for an early-A
His looks right for a 73 up with retarded timing, and especially with a non-functional, or poorly functioning, PCV.
And it is clear to see in his photos that the choke flapper is wide open, with the fast-idle partially engaged. What we don't know is if the fast-idle cam is stuck on it's pivot, or if the spring is not retracting. For the latter there are several reasons; no electricity from the #1 splice, no intake heat from the crossover,a failed choke bi-metallic spring, or a mechanical snag/mislocated link-rod under the little metal cover.
I suppose it could even be that the KD mech is holding it open
Dakota R Keck
Member
Update, traded for a nos carter carb in the box from a buddy i think its a tad bit newer, but it seems to be working fine besides missing a vaccum line that hooks to the breather, no dieseling or flooding i also replaced the thermostat to the choke, since i had it off.
Post some photos please
Any update on your issue?
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