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Old 11-08-2010, 10:25 AM
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Throttle cable on Demon Carb

I picked up a bracket for my Demon carb since the stocker didn't come close to fitting anywhere. My questions are, firstly, is the main cable connected to the right place? When I floor it, all 4 bbls do open up, so I'm assuming that's correct.

2) Are the springs in the right place? When WOT, the springs rub on part of the cable.

3) The lower cable, where does that connect to? The bracket it's on it all the way forward, and doesn't quite reach any holes on the carb. When I squeeze the little diaphram that it's connected to, it only goes back toward the firewall. I have no play to bring it anymore forward.



Again, I apologize if stupid questions. Bought the car totally torn down, and getting it back to par. Car is 75 Monte Carlo, sbc400, 350 auto trans

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Old 11-08-2010, 11:04 AM
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Quote:
Originally Posted by david-b
I picked up a bracket for my Demon carb since the stocker didn't come close to fitting anywhere. My questions are, firstly, is the main cable connected to the right place? When I floor it, all 4 bbls do open up, so I'm assuming that's correct.

2) Are the springs in the right place? When WOT, the springs rub on part of the cable.

3) The lower cable, where does that connect to? The bracket it's on it all the way forward, and doesn't quite reach any holes on the carb. When I squeeze the little diaphram that it's connected to, it only goes back toward the firewall. I have no play to bring it anymore forward.

*SNIP* 350 auto trans
The throttle cable is correct if you get WOT when the pedal is floored from inside the car. Have a helper mat the throttle while you watch to verify the carb is truly wide open.

2. You don't want the springs to rub anywhere. It is better from a throttle shaft and throttle plate wear standpoint to run the springs forward from the linkage below the throttle shaft.

3. The kick down cable should connect to the linkage below the throttle shaft so the cable will be pulled outward as the throttle is opened. But by the looks of things, that carb is not made for a TH350 trans.
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Old 11-08-2010, 11:24 AM
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Quote:
Originally Posted by cobalt327
The throttle cable is correct if you get WOT when the pedal is floored from inside the car. Have a helper mat the throttle while you watch to verify the carb is truly wide open.

Done and Done

2. You don't want the springs to rub anywhere. It is better from a throttle shaft and throttle plate wear standpoint to run the springs forward from the linkage below the throttle shaft.

I've seen this done but saw that the bracket had the holes specifically for it. I'll have to make a little custom bracket since my IM doesn't have any bolts / holes on it for forward springs.

3. The kick down cable should connect to the linkage below the throttle shaft so the cable will be pulled outward as the throttle is opened. But by the looks of things, that carb is not made for a TH350 trans.

Any ideas for this then? I'll see if I can reposition the cable to come more forward. So it should ideally connect to where the springs are located in that pic?

Also, I'm not exactly sure what the kickback cable does. Can someone do a quick 101 lesson on that?

Thanks for your help
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Old 11-08-2010, 12:13 PM
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Also, I'm not exactly sure what the kickback cable does. Can someone do a quick 101 lesson on that?

The kickdown cable makes the Transmision shift into passing gear, also is to let the tranny shift into the other gears,, if that is not hooked up the tranny won't shift correctly,
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Old 11-08-2010, 12:49 PM
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Quote:
Originally Posted by Bad Rat
Also, I'm not exactly sure what the kickback cable does. Can someone do a quick 101 lesson on that?

The kickdown cable makes the Transmision shift into passing gear, also is to let the tranny shift into the other gears,, if that is not hooked up the tranny won't shift correctly,
Got ya.
Do you think I can add a little extension on the cable to reach the linkage?
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Old 11-08-2010, 01:06 PM
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Tech @ BG is a member here who works for BG. Possibly he will see this thread and respond.

I believe I recall that the BG linkage wasn't removable- or something along those lines, so changing the linkage itself could be an issue. That said, I'd be surprised if there wasn't some sort of work around to allow the TH350 kickdown to be connected.

The trans will still shift w/o the kickdown. It will tend to shift earlier w/o it, though. And obviously you won't have a "passing gear" (i.e. an automatic downshift when you floor the throttle from lower speeds).

The trans won't be hurt running w/o the kickdown. You can manually select a lower gear should you need to downshift. That said, I personally like a properly adjusted kickdown unless at the track- where I shift the trans manually anyway.
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Old 11-08-2010, 01:17 PM
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Quote:
Originally Posted by david-b
Do you think I can add a little extension on the cable to reach the linkage?
I looked at another image of a BG carb, and it looks like the hole where you now have the return spring, is where you want the kickdown cable to attach.

I had thought earlier the hole was very small (i.e. 1/16") where the spring is, I see now the hole might be about 1/4"- which will allow a pin to attach for the kickdown cable.

You will need to mount the spring differently, but that shouldn't be a problem.
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Old 11-08-2010, 01:36 PM
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I did this for my kickdown and return spring, the spring is still connected to part of my old Q Jet bracket.
The small bracket on the carb arm is aluminum but I will have to knock one out in steel soon or the spring will cut through it.
Your kickdown cable looked to me to be another throttle cable, mines for a TH700R4.
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Old 11-08-2010, 01:45 PM
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That kickback cable looks completely different than mine. That and the throttle cable look almost identical side by side. One obviously goes to the pedal, the other to the little diaphram thing (great wording I know).

I'll try to see if I connect it to the lower place where the springs are. I want to say I've tried that already, but don't remember offhand at the moment. Just seems like something I would have already done though. I'll try that tonight.
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Old 11-08-2010, 02:59 PM
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Quote:
Originally Posted by david-b
That kickback cable looks completely different than mine. That and the throttle cable look almost identical side by side. One obviously goes to the pedal, the other to the little diaphram thing (great wording I know).
By chance are you talking about the cruise control bellows? Can you take a photo of it?

If so, there's still a kickdown cable missing... Try looking on the side of the trans, towards the bellhousing. You'll be looking for a cable near the dipstick tube on the passenger side of the trans case. The kickdown cable will have a stiff plastic end that has a small (1/4"?) bolt securing it to the trans case. OR- a hole in the case where something like that would go. A small threaded bolt hole next to a larger hole w/a wire protruding from it (or bolt IN the hole, next to a hole in the case) will be the giveaway.

The kickdown cable might have dropped down behind the engine if it's not visible atop the intake manifold or somewhere in the engine compartment.
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Old 11-08-2010, 09:56 PM
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Quote:
Originally Posted by cobalt327
By chance are you talking about the cruise control bellows? Can you take a photo of it?

If so, there's still a kickdown cable missing... Try looking on the side of the trans, towards the bellhousing. You'll be looking for a cable near the dipstick tube on the passenger side of the trans case. The kickdown cable will have a stiff plastic end that has a small (1/4"?) bolt securing it to the trans case. OR- a hole in the case where something like that would go. A small threaded bolt hole next to a larger hole w/a wire protruding from it (or bolt IN the hole, next to a hole in the case) will be the giveaway.

The kickdown cable might have dropped down behind the engine if it's not visible atop the intake manifold or somewhere in the engine compartment.
I wish I had seen this post earlier today before I went to the garage. Off the top of my head, by the dipstick on the trans, right by the cooler lines, there was a yellow/orange line coming out from it. It was a stiffer, throttle-like cable and had an O-ring on the end. That one I goes up and through the firewall. There is another hard line connecting on the drivers side close to the back of the trans with a threaded end that connects in. Can't remember where that connected to on the other end, but I know nothing was hanging. The only 2 cables on the stock bracket were the 2 shown in the pic.

I got the bottom cable where the springs were at, and then since I dont have any places to bolt a bracket for the springs on the front of the IM, just put them against the bracket and the linkage. Just a temp fix, but works pretty good actually.
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Old 11-08-2010, 10:04 PM
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Found the best pic I have from before the motor was in.



You can see the 2 cables coming through the firewall. Top one goes to the gas pedal and the bracket. One below goes to that connection on the trans.
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Old 11-09-2010, 02:54 AM
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Quote:
Originally Posted by david-b
You can see the 2 cables coming through the firewall. Top one goes to the gas pedal and the bracket. One below goes to that connection on the trans.
OK- the bottom cable from the firewall goes to the throttle pedal- and IS the kickdown. This design was used for a couple years (along about '74-'75, IIRC) instead of the more common carb-mounted kickdown. So the throttle and kickdown cables are present and accounted for.

That leaves the other cable at the carb. We know the one is the throttle cable.

Trace the other to where it originates and see if it's a spring loaded "bellows" type affair. If so, that's the cruise control actuator.
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Old 11-09-2010, 08:11 AM
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Quote:
Originally Posted by cobalt327
OK- the bottom cable from the firewall goes to the throttle pedal- and IS the kickdown. This design was used for a couple years (along about '74-'75, IIRC) instead of the more common carb-mounted kickdown. So the throttle and kickdown cables are present and accounted for.

That leaves the other cable at the carb. We know the one is the throttle cable.

Trace the other to where it originates and see if it's a spring loaded "bellows" type affair. If so, that's the cruise control actuator.
Sweet. That makes sense. The other one goes to towards the front of the car to what I will say is the cruise control. You can kind of see the start of it in the trans picture on the lower right. If you push in on the little round part, it pulls the cable.

Next question, so does the CC cable need to be connected to the same location as the throttle cable? Or is down below where I have it fine? Also, there is a vacuum line coming from the CC (more specifically that little silver box on the lower right of that pic) that is teed. 1 side goes to the passenger side, this sphere thing. The other part, not sure. Should that be full vacuum or ported?
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Old 11-09-2010, 08:57 AM
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It's been years since I worked for a GM dealer but iirc somewhere in the early 80's there was a long stud that was used on the Q-jets for both the throttle cable and the cruise.

Cobalt has a lot of background with the Rochester stuff so he may can expand on that.

As far as the throttle location where you have it as long as you can achieve wot as mentioned and the pedal is not too stiff then you should be fine. Normally on my own stuff I will use a bushing in the large hole and locate the throttle there though.

The kickdown also mounts in that lower hole as has already been confirmed.

In regards to the vacuum for the cruise contol going back years ago iirc it is supposed to be ran to full time vacuum.
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