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Old 07-06-2016, 10:25 PM   #1
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no throttle response Chevy 366 Holley 4 barrel

I have a 1987 Chevy bus with a 366 cid and 4 barrel holley carb. Currently the bus will idle, but there is no throttle response. The throttle is stiff, so I believe the redundant safety spring is tripped. Does anyone have a picture and instructions for resetting? I can manually open the secondary and engine revs up. Tomorrow, I will check the secondary diaphragm. I was told that it could be a worn out base plate too. Any thoughts? Am I on the right track? What else should I check?
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Old 07-26-2017, 09:40 PM   #2
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Question No throttle,

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Originally Posted by Meachamr View Post
I have a 1987 Chevy bus with a 366 cid and 4 barrel holley carb. Currently the bus will idle, but there is no throttle response. The throttle is stiff, so I believe the redundant safety spring is tripped. Does anyone have a picture and instructions for resetting? I can manually open the secondary and engine revs up. Tomorrow, I will check the secondary diaphragm. I was told that it could be a worn out base plate too. Any thoughts? Am I on the right track? What else should I check?
Did you ever figure out what this problem was? are you still on this board. Does anyone on this board have any answers to this question?
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Old 07-27-2017, 04:12 AM   #3
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other than checking the linkage, is simple task to get another holly carb, or even quadrajet with its manifold and change. i much prefer the quadrajet and sell the hollys at the swap meet
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Old 07-27-2017, 08:49 AM   #4
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It all depends upon which Holley carb is on the bus.

If the carb is like most that I have seen on buses, the throttle plates are not physically attached to the throttle linkage. The throttle plates are vacuum operated so that they will act as a governor to prevent engine overspeed.

Over time those vacuum actuators can wear out and cease to function.

As far as a stiff throttle linkage is concerned, there could be a lot of reasons for that. The top reason is there is a kink in the cable between the pedal and the carb.

A picture of the carb would be helpful.
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Old 07-27-2017, 03:38 PM   #5
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thank you so much, I drove it and parked it where it is had no problems, been sitting about 6 months, went out and it cranked right up but accelerator is no longer connected to something it will not rev up so I figure it's something simple, it is a 1991 GMC 6000 Fuel injected,366 Tonawanda converted to gas. I will be asking more questions I am sure. Will get a pic of the carb and more info asap.
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Old 07-27-2017, 04:50 PM   #6
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Does it have fuel injection or a carb?

There are a lot of differences between the two.

Regardless of the system, if you move the throttle by hand under the hood do you get full throttle? If you do then you will know the issue is in the linkage. If you don't you will know the issue is inside the carb/FI body.
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Old 07-27-2017, 07:27 PM   #7
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fuel injected
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Old 07-27-2017, 07:29 PM   #8
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as I recall full throttle from under the hood.
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Old 07-28-2017, 12:05 AM   #9
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Okay.

Let's start over.

You have a bus with the 366 big block and it has fuel injection and not a carb.

If you take the air cleaner off and you look at the FI body it should look like a carb with a bunch of wires going to the injectors. There should be a set of throttle plates in the bottom that open and close.

When you push on the throttle inside the bus, what happens to the throttle plates?

If nothing moves then the problem is somewhere between the pedal and the throttle body.

If the cable moves and the throttle plates don't move there is something wrong with the linkage between the cable and the throttle body.

If you can get the throttle plates to move by manually moving the plates while under the hood the problem is going to be somewhere between the pedal and the throttle body.

If you can't get the throttle plates to move then you are going to have to remove the throttle body to discover what it is that is preventing your throttle plates to move.

Pictures of what you have would be helpful.

Good luck!
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Old 07-28-2017, 03:33 AM   #10
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speaking of fuel injection... one can remove and install carb... may need to build intake manifold... my machinest neighbor did that after someone told him it couldnt be done...
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Old 07-30-2017, 02:51 AM   #11
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well the plastic covered dooda to the right of this carb maybe called the (governor?) was plugged with a mud dobbers nest, the cables were not able to function. Cleaned it all out and let penetrating oil work its wonders and wala now it all functions correctly. FYI it is a rochester carb. Any service manuals available to download on this vehicle, chassis or engine/tranny anything at all I would like to have in written form. thanks
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Old 07-30-2017, 11:29 AM   #12
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dont think that is carb... my obscene guess is early fuel inj that often has problems.
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Old 07-30-2017, 02:27 PM   #13
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ok I was all screwed up on that reply it actually was the linkage was seized up and a mud dauber was living in there. Wha'la' everything is fine now.
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Old 07-31-2017, 11:11 PM   #14
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Glad to know you were able to get things going properly.

By the way, that is not a carb. That is a throttle body electronic fuel injection unit. It looks like a carb. It has throttle plates at the bottom like a carb. But it has fuel injectors at the top that inject fuel when and as needed instead of having jets, power valves, accelerator pumps, etc.

The fuel pressure is going to be 2x to 4x higher than a carb.
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Old 08-01-2017, 09:57 PM   #15
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I know you are right about this. I have never had a vehicle this new (1991) or anything fuel injected. I have learned that this motor used to be a diesel but has been converted to gas. YIKES! I am always ready for knowledge. thank you for your reply
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Old 08-02-2017, 02:34 AM   #16
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I know of no engine that was diesel that was converted to run on gas.

Cummins and John Deere made some engines that originally were diesel powered but were converted to run on CNG.

Rausch and a couple of other companies have conversions to change a gas engine into propane power.

The GM Tonawonda tall deck 366/427 gas V-8's were always gas engines originally. There are a few out there that are multi-fuel and run on propane and/or gasoline. And some that are exclusively propane. But I know of none that were converted to run on diesel.

The GM diesel 8.2L Fuel Pincher diesel is about the same size as the 427 but it has nothing in common with the 427 outside of dimensions.

The GM 6.2L/6.5L diesel engines have some gas engine technology in their genealogy but they were only ever diesel engines.

The Toroflow and the Oldsmobile 350 diesel were both gas or diesel powered. The Toroflow was a V-6 and the Olds was a much smaller block V-8.
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