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| Fast Idle Engages During Acceleration https://www.slantsix.org/forum/viewtopic.php?t=44687 |
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| Author: | R. Wood [ Sat Apr 23, 2011 3:25 pm ] |
| Post subject: | Fast Idle Engages During Acceleration |
Hello, This is a Carter BBS on a '75 Valiant. Same one that Charrlie graciously sent me a replacement pump arm screw for. I thought all was well because after warm-up I could knock down the idle by tapping on the gas, as usual. But what happens is that as I take off and accelerate, the fast idle is reengaging. It does respond to my tapping the gas, which makes the car somewhat drivable, but then when I accelerate again it does the same thing. I would like to correct this. Only thing I've done so far is put a few drops of P-Blaster on each of the linkage pivot points. Any ideas as to what I should do next? R. Wood |
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| Author: | wjajr [ Sat Apr 23, 2011 4:44 pm ] |
| Post subject: | |
Lubing carburetor moving parts will work only if you give it a squirt, manually exercise the part sticking until it moves freely, and than flush all lube & dirt off with carburetor cleaner. If parts have any lube on them dust will collect, and cause little free floating parts such as high idle cams to bind. Give all parts that are sticking a good work-out buy moving them by hand, and flush off all lube. Sometimes a rod will egg out its female part, and when linkage moves it will bind. The only cure for this is to dress the offending point of wear with a very fine file or fine sand paper to smooth it up, or fine new parts. |
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| Author: | SlantSixDan [ Sat Apr 23, 2011 4:50 pm ] |
| Post subject: | |
Two possibilities: 1. Your choke thermostat or its pushrod is faulty or improperly formed, so the choke is never quite coming off completely on its own. This is fairly likely because your '75 would have originally come with a Holley 1945, which takes a differently-shaped choke pushrod than the Carter BBS or Holley 1920. The 1945 choke pushrod has a top end that hooks rearward, while the 1920/BBS pushrod's top end hooks frontward. An adaptation of the one to the other is likely not to work as well as it looks as if it should. The choke thermostat you need, if you want to keep an original-type unit, is the 1973-only item. 2. Your throttle spring may not be strong enough to pull the throttle all the way back to curb idle against the drag and weight of the trans kickdown linkage. Remove the air cleaner with the engine hot and running and gently open the throttle slightly by hand, then let it go. Then push it towards the curb idle position and see if the idle slows down. This is likely because starting in '74, all carburetors had inbuilt throttle-return springs; the stretchy spring that was previously the one and only throttle return spring was now just a safety backup spring. You've now got a pre-'74 carburetor (no inbuilt spring). Replace the throttle spring with a new one and adjust the throttle spring bracket to put maximum tension on the spring. |
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| Author: | R. Wood [ Sun Apr 24, 2011 10:49 am ] |
| Post subject: | |
Thanks for the help, and yes, I've been running the choke that came with the original 1945 (and it probably didn't work then either). I have a CarbsOnly electric choke on my bench, so the skywriting must be telling me to finally put it in. This one is not a 'drop in' fit; I'll need to fabricate a plate to mount it offset so that it links up nicely with the BBS. I'll make sure to max out that spring tension, too - I didn't realize that was so important. I appreciate the tips. R. Wood |
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| Author: | SlantSixDan [ Sun Apr 24, 2011 11:03 am ] |
| Post subject: | |
Which (exact) electric choke kit do you have? A #1231 would bolt onto your exhaust manifold (with only one bolt) and would hook right up to the BBS. A #1233 is the exact precise correct one for your application. A #1234 has the rear-hook pushrod to suit the 1945. #1233s are hard to come by, IME. Probably your easiest way forward is a #1234 kit with a new pushrod bent (by you) out of appropriate-diameter brass rod from the hardware store. |
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