This is how it is all the time and after trying to kick down to start. Once it "starts" goes immediately to wide open. when vehicle shuts off it goes to one more step up. By start I mean run for 1 second then die.
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| Choke & fast idle cam not functioning after carb rebuild. Holley 1945 https://slantsix.org/forum/viewtopic.php?t=65095 |
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| Author: | joepipecutter [ Fri Jul 10, 2020 9:48 am ] |
| Post subject: | Choke & fast idle cam not functioning after carb rebuild. Holley 1945 |
Hello and forgive any ignorance I may have as I am new to this board and this is my first ever project. 1980 D150. I just rebuilt my first carburetor, Holley 1945 and all went smoothly until I mounted it back on my vehicle. The choke and fast idle cam are not operating as they should. When I depress the accelerator the fast idle cam falls the opposite way to the hot position and wide open choke, and the choke seems to stay in 3/4 wide open position at all times. When vehicle is shut off, the idle screw will go into the 3rd step of cam. I believe I have made all the adjustments necessary according to the service manual, fast idle, choke unloader, vacuum kick, etc. and there is no binding in choke and choke diaphragm is fine. I would also add that choke system worked perfectly before rebuild. Reason for rebuild was because of hot starting and dying on acceleration, both issues were resolved. Vehicle runs very well when warm, but dies immediately after starting. I took pics of linkage positions before and after rebuild if those would help. |
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| Author: | SlantSixDan [ Fri Jul 10, 2020 10:17 am ] |
| Post subject: | Re: Choke & fast idle cam not functioning after carb rebuild. Holley 1945 |
Yup, please post your pics. |
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| Author: | joepipecutter [ Fri Jul 10, 2020 1:02 pm ] |
| Post subject: | Re: Choke & fast idle cam not functioning after carb rebuild. Holley 1945 |
This is how it is all the time and after trying to kick down to start. Once it "starts" goes immediately to wide open. when vehicle shuts off it goes to one more step up. By start I mean run for 1 second then die. |
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| Author: | SlantSixDan [ Fri Jul 10, 2020 1:06 pm ] |
| Post subject: | Re: Choke & fast idle cam not functioning after carb rebuild. Holley 1945 |
You've got an incompatible choke thermostat/carburetor combo there. That's a '70-'72 Holley 1920 choke (with bent and brutalized pushrod that would render it useless even with a compatible carb) and a '74-up Holley 1945 carburetor. The 1945's choke lever requires a different kind of choke pushrod; this hacked and bent 1920 choke pushrod appears to be interfering with the proper operation of the rest of the linkage. The 1945-compatible choke thermostat is not compatible with the '70-'72 exhaust manifold you're running. Get a № 1234 electric choke kit and install it and your troubles should be over (though these '70-'72 exhaust manifolds have a gasket under the choke cup that is no longer available; you will have to cut your own new replacement gasket from appropriate high-temp gasket material). |
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| Author: | joepipecutter [ Fri Jul 10, 2020 1:13 pm ] |
| Post subject: | Re: Choke & fast idle cam not functioning after carb rebuild. Holley 1945 |
Thanks, ordered the kit. I'll update with info and pics for others. |
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| Author: | matv91 [ Fri Jul 10, 2020 3:33 pm ] |
| Post subject: | Re: Choke & fast idle cam not functioning after carb rebuild. Holley 1945 |
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| Author: | matv91 [ Fri Jul 10, 2020 3:39 pm ] |
| Post subject: | Re: Choke & fast idle cam not functioning after carb rebuild. Holley 1945 |
The U shape looks a little wide in your picture. What base gasket did you use, thinner one maybe? |
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| Author: | joepipecutter [ Sat Jul 11, 2020 9:00 am ] |
| Post subject: | Re: Choke & fast idle cam not functioning after carb rebuild. Holley 1945 |
When I did the pull off test it was a little off but it had worked fine so did not adjust. I may have not done the test correctly as the instructions were a little hard to figure out as it is my first time doing it. "Slight drag" and "light closing pressure" mean different things to different people. My guess would be it was widened to compensate for the incorrect thermostat and link as slandsixdan pointed out above. Also, this was a Canadian truck and some settings are different. I used the gasket that came with the kit, it was the same size as the previous gasket which is about 1/2 inch I would guess. I found a video on YouTube that better illustrates how to do the test and will be doing it again to make sure it is correct for when I install the new choke. |
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