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12-17-2020, 11:27 PM | #1 |
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Choke/throttle rods set up
I've got something connected wrong on my choke/throttle setup. The throttle is very stiff. When the choke is pulled full out for starting, the engine races as the starts. It is a '39 pickup 85 carb # 94, 91-99. The choke does not push full in.
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12-18-2020, 07:43 AM | #2 |
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Re: Choke/throttle rods set up
Clem the rods on my 39 pkp. Took some tweaking , bending to get to not bind on the new dash grommets . I am still not able to get the throttle to stay where. I want it .Sunshine
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02-15-2021, 10:29 PM | #3 |
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Re: Choke/throttle rods set up
Mt throttle slides back as well. I give up.
Clem |
02-16-2021, 11:34 AM | #4 |
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Re: Choke/throttle rods set up
The throttle on my stock '46 Coupe won't stay where I set it, and returns to idle. Were they ever built to stay where they were set? Can they be repaired to stay set, and how?
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02-16-2021, 11:43 AM | #5 |
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Re: Choke/throttle rods set up
Same trouble with the throttle on my "36. Somebody said they used a clothes pin to keep it in place. Maybe i'll just do the same. Terry
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02-16-2021, 11:48 AM | #6 |
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Re: Choke/throttle rods set up
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02-16-2021, 09:00 PM | #7 |
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Re: Choke/throttle rods set up
My 41 used to stay in place.
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02-17-2021, 06:54 AM | #8 |
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Re: Choke/throttle rods set up
I improved movement through the firewall by bending the rods and putting a little silicone grease on the rod where it passes through the firewall grommet.
Regarding the slipping of the throttle rod, I have a small hose clamp on the back side of the instrument panel grommet that tightens the grommet to rod enough to keep it from sliding easily. Glenn |
03-10-2021, 05:35 PM | #9 |
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Re: Choke/throttle rods set up
I find that when the '39 /85 hp truck starts with the the throttle full in and the chock sliding in from full out, it immediately goes to hi rpm? I catch it with the ign switch. The butterflies seem to move correctly. I do not have a elect. fuel pump
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03-10-2021, 08:11 PM | #10 |
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Re: Choke/throttle rods set up
If I understand your question: When the choke is pulled out, the throttle is advanced and won't release until the accelerator is patted. Sliding the choke to a reduced position won't release the throttle by itself.
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03-10-2021, 10:42 PM | #11 |
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Re: Choke/throttle rods set up
Maybe you are right. Could I have the throttle installed wrong? That funny round nut seems to have two positions?
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03-11-2021, 10:33 AM | #12 |
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Re: Choke/throttle rods set up
So, when you "catch it with the ignition switch" have you looked at the carburetor to see what is holding the throttle open? I suggest disconnecting the hand throttle rod completely and just start the engine using the choke and foot pedal and see if you still have issues.
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03-12-2021, 06:08 PM | #13 |
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Re: Choke/throttle rods set up
Never thought of that.
Today I trued to start the engine to no avail. I primed it and it started and backfired up thru the carb. A couple of starts and hi rev occurred, so I quit. |
03-13-2021, 11:08 AM | #14 |
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Re: Choke/throttle rods set up
I once had a lawn tractor (Simplicity) that had a push/pull throttle. It had a speed control built into the dashboard mount for the cable mechanism. You could pull the throttle out to your desired engine speed, then lock it in place by rotating the knob clockwise. When you desired to reduce the RPM's you would turn it counter-clockwise to its free position. You could then, push in or pull out as desired. This works similar to a drill chuck or collet, that applies a locking force on the sliding shaft, which is a little larger (about 1/4" OD) than the cable itself. That principle could be applied here to the hand throttle if one could find a mechanism like i described.
Al Hook |
03-13-2021, 12:51 PM | #15 |
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Re: Choke/throttle rods set up
thanks. I'm thinking a good "brogan maintenance" kick would help as a well.
As a very young pilot flying the BoeingWB-50, we had the props go out of electric sync. The control box had a bunch of spring bells it and lots of electrical contacts to keep the props in sync with the masker. I watched my engineer front his seat reach out an kick the control box. The box went "brrrrrasfwewf" shaking on its spring mounts. The props changed speeds with loud noises and settled back in positions. God love the senior flight engineers!! |
03-14-2021, 04:54 PM | #16 |
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Re: Choke/throttle rods set up
No luck at all.
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03-16-2021, 02:18 PM | #17 |
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Re: Choke/throttle rods set up
Ideas, please
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03-16-2021, 05:09 PM | #18 |
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Re: Choke/throttle rods set up
Hi Clem,
As mentioned above, you need to see what is either hanging up the choke and throttle rods or the position of the choke plate. I would shut it off shortly after it races without touching the throttle pedal or the choke and throttle rods. Have the air filter off and just look at the position of the carb plate and carb throttle shaft and linkage. Just look at first and if something is not returning you can nudge things one by one to see what's hanging up. If you don't see anything you may have a large vacuum leak. Turn the idle screws all in and count the turns back them out so you're in maybe 1/2 turn or more in from were you started. Start it up and the RPMs should be reasonable. If not shut it off and turn the screws in more. You can find the leak using carb cleaner or propane used very carefully, no sparks flames, etc. When you pass say a low puff of propane over the leak source, the RPMs will climb. Glenn |
03-16-2021, 06:46 PM | #19 |
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Re: Choke/throttle rods set up
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03-16-2021, 07:14 PM | #20 |
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Re: Choke/throttle rods set up
Some other things to consider...after reading the V Tardel's booklet #7 Stromberg 97 there were some assembly tips worth noting and may apply.
My 39 has a Stromberg, there are a bunch of small springs on that carb and a darn $2.00 baby return spring might be it. Ensure we also do not have some wear in the throttle body bore, binding. Also the ball ends of the throttle-linkage do wear and can cause binding, sand paper and a small round file to round out the ball if misshapen. Tighten the choke pivot and levers, and make sure the throttle linkage is @ about 90 degrees. Again this applies to a 97 but probably similar to a Holley. |
03-16-2021, 09:26 PM | #21 |
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Re: Choke/throttle rods set up
Thanks. It popped once today
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03-17-2021, 06:30 PM | #22 |
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Re: Choke/throttle rods set up
Some pictures Clem, quite a few but it should help. The first picture show the throttle and choke all in, mostly there after warm up and while driving. They equally stick out about a 1/4".
While closed measurements from the firewall grommet down to the rod ends, throttle approx 16 1/8" and choke approx 14 3/8" Several pictures of the rods extending down to the carb and the last two tape measure pictures show my rods pulled out as if I were to start the truck. Throttle 15 1/4" and choke 12 3/4". I will say The throttle rod always wants to close back down but I just manually keep it open some while the engine warms. My garage is heated and typically close that choke down to minimum, less than a minute. The last few pictures give you an idea of the bends out the fire wall to the carb. Last edited by 39portlander; 03-18-2021 at 03:20 PM. |
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03-19-2021, 09:33 PM | #23 |
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Re: Choke/throttle rods set up
You guys are such a great help. Particularly in the time of no home visits. I have 3 X 91-99Fod cards. One on my '39 one on the 40' Merc and spare. At the 9199 on the Merc, I looked at the position of the round retainer on the throttle shaft(can't find the name of to.) The nut on the '39 was in the other position from the one on the '40 Merc. The '39 has started every time without choke since. I do have to be sure the c/t are full in. I'm hoping it got it right. Should be a good day tomorrow to go around the block
Thanks again. Clem |
03-22-2021, 11:10 AM | #24 |
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Re: Choke/throttle rods set up
Still trouble. I'm hopping for a gas runtoday.
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04-01-2021, 01:02 PM | #25 |
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Re: Choke/throttle rods set up
Every time I start it, there is a backfire up thru the carb. Could I have a burnt valve of maybe carbon on the valve seat?
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04-01-2021, 01:21 PM | #26 | |
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Re: Choke/throttle rods set up
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Quote:
When is the last time that carb was rebuilt or saw any attention? Maybe it's just carb problems, nothing to do with the choke and throttle rods? Maybe try one of your known working carbs from either of your other working vehicles.
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04-01-2021, 02:10 PM | #27 |
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Re: Choke/throttle rods set up
I rebuilt that carb and the spare 2-3 years ago. All was fine until a couple of months back
Thanks |
04-04-2021, 01:16 AM | #28 |
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Re: Choke/throttle rods set up
The rod connecting the two butterfly disks connects to linkage on the outside of the carb(91-99) and is secured by a round "NUT" with two positions for locking in place. I don't have info as to which of the two options slots to use. I have tried both slots and continue to get a backfire up thru the carb.
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04-04-2021, 09:06 AM | #29 | |
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Re: Choke/throttle rods set up
Quote:
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04-04-2021, 02:18 PM | #30 |
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Re: Choke/throttle rods set up
Thanks. I'll go check
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04-04-2021, 09:53 PM | #31 |
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Re: Choke/throttle rods set up
Being an "8BA guy", I had never seen this type of linkage, although I do know my way around the later 94's. When I went to rebuild one of these, I couldn't get it apart and didn't want to force it. I asked for advice here, and found out what to do. It did take quite a bit of force to get it to move; more than I would have originally thought.
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07-25-2021, 12:25 AM | #32 |
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Re: Choke/throttle rods set up
Still on cold starts, something binds causing the engine to speed up. I control the high rpm with the ign switch. Today
it took several trys before the engine would no race up. Driving me nuts. The engine oil was changed in late spring and is now black again. Am I loosening deposits by the hi rpm? My fresh oil got black in a few short drives. Is the higher rpm loosening oil deposits? |
07-25-2021, 10:42 AM | #33 |
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Re: Choke/throttle rods set up
I also had issues with my choke/throttle on my 47 Ford. The choke would always slide causing the engine to shut down. On the firewall 2 metal L clips hold the choke and throttle in place. Most vintage ford stores dont sell these. Most people will tend to fabricate the L clips. Once i got a pair of these L clips my choke stays perfectly in place as i drive my car for over an hour or so. Also, i never bother with the throttle, i dont move it or nothing. For me, the choke is the only rod i move when needed.
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