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07-27-2017, 09:53 AM | #1 |
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Throttle linkage problem.........
I have been struggling with a nagging problem in my throttle linkage for some time now and I could use some advice from you folks. I have twin 94's on an Edelbrock intake on the '50 mercury engine in my '32. I am using the stock gas pedal and a modified link to the front carb. The carbs are linked together on the driver's side. The problem I am running into is a, for lack of a better description, hard spot in the throttle right off of idle. In other words, I have to push the pedal pretty hard to get past this "hard spot" to pick up speed and then it really takes off! Too much! Obviously it is binding up right off of idle but for the life of me I cannot find out where. I have lubed and inspected the linkage from one end to the other. What am I missing?
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07-27-2017, 10:11 AM | #2 |
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Re: Throttle linkage problem.........
Does it do it if you disconnect the linkage between the two carbs? Also, looking at the photo of the drivers side linkage it appears the front carb is ahead of the rear. Make sure the butterfly in the rear carb isn't closing off before the front causing a binding situation.
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07-27-2017, 10:12 AM | #3 |
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Re: Throttle linkage problem.........
Any chance the throttle plates are sticking in the throat of the cabs? I would remove the connecting linkage and check each carb separately to see if one or both of the throttle plates are hanging up.
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07-27-2017, 10:21 AM | #4 |
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Re: Throttle linkage problem.........
You could disconnect the carb link with spring tension added to free one.
Now play with the idle speeds to be equal one carb at time.Put linkage back on. See if that help. |
07-27-2017, 11:40 AM | #5 |
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Re: Throttle linkage problem.........
Ken, I will try running it on just the front carb to see if it is free then. That will tell me something if it is.
JSeery, I checked the throttle plates first thing to make sure they weren't binding or hanging up. No problems there.
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07-27-2017, 11:44 AM | #6 |
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Re: Throttle linkage problem.........
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07-27-2017, 11:54 AM | #7 |
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Re: Throttle linkage problem.........
(1)Put the return spring on the other side, where the two carbs connect. Maybe.
(2)I noticed the sharp angle of the right side, where the first part of the linkage hooks to the carb. Changing this angle will help, more toward 90 degrees. Better leverage for the start of the pull. Karl |
07-27-2017, 12:32 PM | #8 |
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Re: Throttle linkage problem.........
^^^
I was thinking the same thing; that angle on carb connection looks pretty sharp; funny geometry could result in the foot pedal action you describe. |
07-27-2017, 12:50 PM | #9 |
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Re: Throttle linkage problem.........
I don't know anything about solving your problem
but would some type of BELL CRANK arrangement help? |
07-27-2017, 12:50 PM | #10 | |
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Re: Throttle linkage problem.........
Quote:
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07-27-2017, 12:52 PM | #11 |
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Re: Throttle linkage problem.........
you could use a uni-syn to synchronise them - to do it properly you need to disconnect the carbs from each other and set up the idle on them individually. once you have each carb flowing the same then put your linkage back on.
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07-27-2017, 01:56 PM | #12 |
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Re: Throttle linkage problem.........
Your problem is that your carb connection wants to travel in an arc and you are pulling on it at idle in a more linear motion. By this I mean that your carb connection is slightly over center towards 1 oclock and you have to force it past noon towards 11 oclock before it will travel smoothly around the arc. Modify your linkage connection at the carb so that you are pulling over the top of the arc instead of thru it. You could accomplish the same thing by raising the connection point at the firewall but you may lose some WOT motion by changing that end.
Last edited by Kruzn40; 07-27-2017 at 02:04 PM. Reason: spelling |
07-27-2017, 02:05 PM | #13 | |
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Re: Throttle linkage problem.........
Quote:
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07-27-2017, 02:21 PM | #14 | |
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Re: Throttle linkage problem.........
Quote:
OK, to be more precise let's use 5, 6, and 7 o'clock instead. The theory remains the same. |
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07-27-2017, 03:13 PM | #15 | |
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Re: Throttle linkage problem.........
Quote:
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07-27-2017, 03:34 PM | #16 |
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Re: Throttle linkage problem.........
Is it possible that the tang of the return spring is causing binding where it is attached?
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07-27-2017, 03:35 PM | #17 |
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Re: Throttle linkage problem.........
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07-27-2017, 03:40 PM | #18 |
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Re: Throttle linkage problem.........
I have tried the spring on both sides and can see no difference.
I appreciate the ideas you all are coming up with and I am looking forward to trying some of them out in the AM when I get to the shop. It always seems to help to have "another pair of eyes" on a problem. Thanks guys.
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07-27-2017, 04:02 PM | #19 |
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Re: Throttle linkage problem.........
Not being intimately familiar with a 94 carb and the linkage attachment point not being clear in the small photo, I assumed it to be at situated above the throttle shaft instead of the bottom. In this case you obviously want to lower the linkage rod to achieve as near 90 degree angle as possible with respect to the throttle shaft.
I have solved this exact problem on a couple of occasions by changing the rod geometry. |
07-27-2017, 04:23 PM | #20 |
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Re: Throttle linkage problem.........
Loosen the mounting nuts on both bases, adjust the linkage until it's smooth, then re-tighten the mounting nuts.
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