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Jared
Top Member
USA
1865 Posts |
 Posted - 01/07/2012 : 6:49:48 PM
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So I cant for the life of me figure this out. My bus used to go roughly 62-63 miles per hour before "a" governor would kick in and cut the fuel. Now for the past 4 months or so its been lowered to 49 mph exactly. I unhooked the wire on the governor on the Holley 4152eg but that did not changed anything. Ive read that the Allison AT4545 has a governor on it as well. would there be any reason for this governor to have kicked down to only 49mph? Is there any other governor I should be looking for?
Thanks as always....
366 gas / AT545 |
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dwight
Senior Member
USA
58 Posts |
Posted - 01/07/2012 : 10:07:54 PM
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| Does the engine run out to it's full rated rpm in the lower gears? Years ago we had a redundant throttle return spring on the side of the carb that had to be reset if it disengaged. |
20 SCHOOL BUS FLEET OWNER/OPERATOR (Retired) |
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Jared
Top Member
USA
1865 Posts |
Posted - 01/08/2012 : 06:29:26 AM
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quote:
Originally posted by dwight
Does the engine run out to it's full rated rpm in the lower gears? Years ago we had a redundant throttle return spring on the side of the carb that had to be reset if it disengaged.
dwight, I dont have a tachometer but to be honest it does kind of sound like the engine is running out of its full rater rpms too early like you said. Can you be more specific on how to reset the return spring?
thanks so much for your insight. |
http://www.flickr.com/photos/jaredg21/sets/ |
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matts4290
Advanced Member
224 Posts |
Posted - 01/08/2012 : 3:55:42 PM
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I don't think any governors on the trans would affect any of the power being inputted into it (the trans).
Last I knew, the governor on the trans would upshift the transmission if the input shaft was spinning too fast.
Somebody correct me if I'm wrong. |
We can't all be conventional!
http://www.youtube.com/user/matts4290 |
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bwest
Administrator
United States
3820 Posts |
Posted - 01/08/2012 : 7:24:03 PM
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| I'd agree with matts4290 but just in case I have seen these things get a hole in the vaccumn line going to the modulator. There should be as steel line running from your carb down to the transmission. The ends of it may change to rubber. Anyway, check it all over because I have seen them have a hole rubbed in them down around the bell housing area. |
Bryan |
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Cal Mc
Advanced Member
303 Posts |
Posted - 01/09/2012 : 06:41:50 AM
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I think that dwight has it right. The redundant throttle return spring is actually a saftey measure. If the throttle return spring breaks there is a secondary return spring.
If the throttle feels a lot heavier than it should you will have to reset the throttle mechanism to give you full throttle. Check the throttle return spring arm. The arm should seat into the bottom of a V notch on the throttle mechanism[about 1 1/2 inches below where the spring hooks to the arm] |
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Fastback
Top Member
1500 Posts |
Posted - 01/09/2012 : 07:59:43 AM
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quote:
Originally posted by Cal Mc
I think that dwight has it right. The redundant throttle return spring is actually a saftey measure. If the throttle return spring breaks there is a secondary return spring.
If the throttle feels a lot heavier than it should you will have to reset the throttle mechanism to give you full throttle. Check the throttle return spring arm. The arm should seat into the bottom of a V notch on the throttle mechanism[about 1 1/2 inches below where the spring hooks to the arm]
I agree, if I remember correctly the carb. will not open fully if the redundant mechanism is tripped. And all it takes to trip it is to grab where the normal return spring attaches to carb and "blip the throttle". This trips the much heavier coiled around the throttle shaft redundant spring into service. |
Why yes, the ORIGinal CHARGER is a Fastback |
Edited by - Fastback on 01/09/2012 08:00:09 AM |
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dwight
Senior Member
USA
58 Posts |
Posted - 01/09/2012 : 1:22:24 PM
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Jared
The carb throttle linkage must have two return springs. One for the linkage connecting to the carb and the redundant spring on the side of the carb itself. Be careful with your fingers when you reset the redundant spring linkage. |
20 SCHOOL BUS FLEET OWNER/OPERATOR (Retired) |
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bwest
Administrator
United States
3820 Posts |
Posted - 01/09/2012 : 2:26:39 PM
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| I forgot about that system. It is a bear to reset! Wonder if he will have to take the carb off to do it? |
Bryan |
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Jared
Top Member
USA
1865 Posts |
Posted - 01/09/2012 : 3:57:39 PM
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quote:
Originally posted by bwest
I forgot about that system. It is a bear to reset! Wonder if he will have to take the carb off to do it?
Oh boy I hope not....In any case I cant thank you guys enough for your help. Hopefully I can somehow obtain decent weather this weekend to try your suggestions...Again thanks fellas! |
http://www.flickr.com/photos/jaredg21/sets/ |
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Fastback
Top Member
1500 Posts |
Posted - 01/10/2012 : 12:54:48 PM
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quote:
Originally posted by Jared
quote:
Originally posted by bwest
I forgot about that system. It is a bear to reset! Wonder if he will have to take the carb off to do it?
Oh boy I hope not....In any case I cant thank you guys enough for your help. Hopefully I can somehow obtain decent weather this weekend to try your suggestions...Again thanks fellas!
I don't think you will have to pull the carb off, just study it and realize there must be a spring from an "arm" on carb to a bracket on an intake manifold bolt inorder to keep the safety "redundant" spring caged. Watch your fingers, resetting the mechanism is a little like setting a rat trap. |
Why yes, the ORIGinal CHARGER is a Fastback |
Edited by - Fastback on 01/10/2012 12:55:26 PM |
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Jared
Top Member
USA
1865 Posts |
Posted - 01/10/2012 : 4:34:00 PM
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quote:
Originally posted by Fastback
quote:
Originally posted by Jared
quote:
Originally posted by bwest
I forgot about that system. It is a bear to reset! Wonder if he will have to take the carb off to do it?
Oh boy I hope not....In any case I cant thank you guys enough for your help. Hopefully I can somehow obtain decent weather this weekend to try your suggestions...Again thanks fellas!
I don't think you will have to pull the carb off, just study it and realize there must be a spring from an "arm" on carb to a bracket on an intake manifold bolt inorder to keep the safety "redundant" spring caged. Watch your fingers, resetting the mechanism is a little like setting a rat trap.
Will do. Thanks for the help! |
http://www.flickr.com/photos/jaredg21/sets/ |
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bwest
Administrator
United States
3820 Posts |
Posted - 01/10/2012 : 7:03:03 PM
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| There's like a notch and a finger that goes into it isn't there? All I can remember is having these out and rebuilding them. I always kept one rebuilt and sealed in a box. Had to replace about 1 per year out of a fleet of about 12 of these carbs. |
Bryan |
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dwight
Senior Member
USA
58 Posts |
Posted - 01/11/2012 : 02:17:32 AM
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Jared
The 4152G carb was a piss poor design. The Allison engineers in all their glory said that to use their transmissions, a RPM governed engine was required to be in front of it. That meant a automatic choke carb was not compatible. (Have you ever heard of a automatic transmission automobile with a manual choke?)
So Chevy-Dodge-Ford-Gmc-International all used the Holly 2300 style 2bl or the 4150 4bl. with a RPM limiting governor build into the carb base plate. The dam fools at Holly installed a spring on one side of the carb base plate to pull the carb wide open throttle and the School Bus chassis manufacture had to put a heavy return spring on the accelerator linkage to try to bring the carb back to a normal idle RPM.
The School Bus driver had to have a very large right leg to be able to push the gas pedal down and it actually caused the driver to use partial throttle on acceleration resulting in taking longer to shift into high gear and lowered the average MPG. The "Engineers" at Allison didn't realize that caused the transmission to shift gears when in a high torque lower RPM mode which resulted in clutch plate slippage and early transmission failure. As per the "GM code of conduct", they were required to say, "We have never heard of that problem".
Meanwhile back at the Holley Carb, the entire base plate and butterfly assembly is worn out prematurely because the carb linkage is trying to twist sideways from the springs pulling in opposite directions with the Governor trying to pull the throttle wide open. By the way, did I forget to mention that if the throttle return spring should fail, the engine will immediately go to wide open throttle and the transmission will downshift for faster acceleration and power. A School Bus Drivers nightmare and it took another 10 years before we saw the safety redundant spring installed on the Holley Carb.
The worn out Carb base plate and the soot blown back into the carb passages when the cold engine coughed because the dam manual holley choke was engineered with the wrong spring tension meant that the Carb was a maintenance nightmare. The answer was to discard the original Carb and replace it with the similar Carb with a Automatic Choke, NO RPM GOVERNOR, and a smaller THROTTLE RETURN SPRING.
Dwight |
20 SCHOOL BUS FLEET OWNER/OPERATOR (Retired) |
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Thomasbus24
Administrator
USA
4547 Posts |
Posted - 01/11/2012 : 05:21:43 AM
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| Wow. Any I thought today's "engineering" was bad... |
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Jared
Top Member
USA
1865 Posts |
Posted - 01/11/2012 : 05:47:26 AM
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quote:
Originally posted by dwight
Jared
The 4152G carb was a piss poor design. The Allison engineers in all their glory said that to use their transmissions, a RPM governed engine was required to be in front of it. That meant a automatic choke carb was not compatible. (Have you ever heard of a automatic transmission automobile with a manual choke?)
So Chevy-Dodge-Ford-Gmc-International all used the Holly 2300 style 2bl or the 4150 4bl. with a RPM limiting governor build into the carb base plate. The dam fools at Holly installed a spring on one side of the carb base plate to pull the carb wide open throttle and the School Bus chassis manufacture had to put a heavy return spring on the accelerator linkage to try to bring the carb back to a normal idle RPM.
The School Bus driver had to have a very large right leg to be able to push the gas pedal down and it actually caused the driver to use partial throttle on acceleration resulting in taking longer to shift into high gear and lowered the average MPG. The "Engineers" at Allison didn't realize that caused the transmission to shift gears when in a high torque lower RPM mode which resulted in clutch plate slippage and early transmission failure. As per the "GM code of conduct", they were required to say, "We have never heard of that problem".
Meanwhile back at the Holley Carb, the entire base plate and butterfly assembly is worn out prematurely because the carb linkage is trying to twist sideways from the springs pulling in opposite directions with the Governor trying to pull the throttle wide open. By the way, did I forget to mention that if the throttle return spring should fail, the engine will immediately go to wide open throttle and the transmission will downshift for faster acceleration and power. A School Bus Drivers nightmare and it took another 10 years before we saw the safety redundant spring installed on the Holley Carb.
The worn out Carb base plate and the soot blown back into the carb passages when the cold engine coughed because the dam manual holley choke was engineered with the wrong spring tension meant that the Carb was a maintenance nightmare. The answer was to discard the original Carb and replace it with the similar Carb with a Automatic Choke, NO RPM GOVERNOR, and a smaller THROTTLE RETURN SPRING.
Dwight
Well I will tell you that the accelerator pedal is rather stiff. Also, I found this doc online:
http://webmain02.fire.ca.gov/Pubs/Issuance/6700/fnf061.pdf
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http://www.flickr.com/photos/jaredg21/sets/ |
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Cal Mc
Advanced Member
303 Posts |
Posted - 01/11/2012 : 06:11:02 AM
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Correct instructions ...difficult to understand.
-disconnect the throttle return spring
-rotate throttle to full open postion using rod from throttle pedal
-while holding throttle in full open position pull return spring lever back into V notch[IF THE LEVER DOES NOT MOVE EASILY TO THE BOTTOM OF THE V NOTCH THE THROTTLE IS NOT OPEN FULL]
-while holding lever in V notch, rotate throttle to closed position
-continue holding lever in V notch, hook up throttle return spring
-WATCH YOUR FINGERS |
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bwest
Administrator
United States
3820 Posts |
Posted - 01/11/2012 : 09:56:57 AM
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| I like that last phrase "WATCH YOUR FINGERS" Priceless!! |
Bryan |
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dwight
Senior Member
USA
58 Posts |
Posted - 01/20/2012 : 3:47:33 PM
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Jared
Waiting to hear what problem you found. If this is your personal bus, what do you use it for?
Dwight |
20 SCHOOL BUS FLEET OWNER/OPERATOR (Retired) |
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Jared
Top Member
USA
1865 Posts |
Posted - 03/04/2012 : 3:42:07 PM
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quote:
Originally posted by dwight
Jared
Waiting to hear what problem you found. If this is your personal bus, what do you use it for?
Dwight
Well I finally got a chance to reset the return spring like everyone suggested. It took a few minutes to understand the V-notch thing but I got it and it certainly fixed my "stiff" accelerator pedal issue. The pedal feels much smoother and lighter than ever.
the bad news is that it still taps out at 49 mph. What else would cause this? Do you think my secondaries arent openning and causing this? I swear I used to get her up into the low 60s |
http://www.flickr.com/photos/jaredg21/sets/ |
Edited by - Jared on 03/04/2012 3:42:54 PM |
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Fastback
Top Member
1500 Posts |
Posted - 03/05/2012 : 07:44:34 AM
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| Could be, they can stick from lack of use |
Why yes, the ORIGinal CHARGER is a Fastback |
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Jared
Top Member
USA
1865 Posts |
Posted - 03/05/2012 : 11:18:56 AM
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quote:
Originally posted by Fastback
Could be, they can stick from lack of use
If the secondaries aren't opening, would that in itself cause the bus to reach an exact top speed (49mph) and then stop accelerating?
I just bought a factory tachometer on Ebay (off of a 1983 GMC 6000) and am hoping to hook this up to see if I'm hitting the same exact RPM when I hit 49mph. |
http://www.flickr.com/photos/jaredg21/sets/ |
Edited by - Jared on 03/05/2012 11:20:18 AM |
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Jared
Top Member
USA
1865 Posts |
Posted - 05/13/2012 : 10:22:14 AM
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| So I was able to correct the redundant throttle spring and figure out the how to get the bus to go above 49 mph. For some reason though after I reset the throttle spring I've noticed that the when I put the bus in reverse the accelerator pedal sometimes actually pushes itself down automatically!! Its very scary as the bus is gaining acceleration in reverse by itself. I usually throw it into neutral and notice the accelerator pedal pop back up to its idle position. does anyone know what would cause this? |
http://www.flickr.com/photos/jaredg21/sets/ |
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Fastback
Top Member
1500 Posts |
Posted - 05/14/2012 : 11:54:08 AM
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Check for any idle speed control solenoids on the carb, if presant they should control idle speed the same no matter if bus is in any gear or not. After all these years who nows what could be hooked to what.
Also the original hookup on this bus from accelerator pedal to carb should be a cable that ends with a connection on the engine. If that has been altered it may allow throttle to open farther as engine "torques" to one side when in gear. Again many hands over many years may have messed with things. |
Why yes, the ORIGinal CHARGER is a Fastback |
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dwight
Senior Member
USA
58 Posts |
Posted - 05/15/2012 : 12:54:38 AM
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Jared
What year and make chassis do you have?
Have you checked the motor mounts for excessive movement? Bolts tight?
Open the hood and watch the engine movement while someone else starts the engine and puts the transmission in Drive and accelerates while holding the brakes tight. Do the same test in Reverse. Excessive engine movement? |
20 SCHOOL BUS FLEET OWNER/OPERATOR (Retired) |
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Jared
Top Member
USA
1865 Posts |
Posted - 05/15/2012 : 04:20:03 AM
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quote:
Originally posted by dwight
Jared
What year and make chassis do you have?
Have you checked the motor mounts for excessive movement? Bolts tight?
Open the hood and watch the engine movement while someone else starts the engine and puts the transmission in Drive and accelerates while holding the brakes tight. Do the same test in Reverse. Excessive engine movement?
Thanks for the replys guys.....I have a 1987 Chevrolet B-60 chassis with a 366 gasser. I'll certainly try your test for engine movement. Would that cause this "reverse" sudden acceleration problem? |
http://www.flickr.com/photos/jaredg21/sets/ |
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Topic |
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Allison Trans governor?
