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#42779 03/31/2005 4:08 PM | Joined: May 2001 Posts: 1,904 'Bolter | | 'Bolter Joined: May 2001 Posts: 1,904 | Last year when I first got my rebuilt 261 going with a rebuilt Rochester Monojet carb, things were great. But as time went on, it has become more difficult for me to adjust the carb. And yesterday it started whistling.
Is the whistling a symptom of something specifically wrong or is it something I just have to live with?
(I'm going to look at a Carter YF that Stevejumpr gave me a lead on so I hope I won't have to put up with the whistle for long.)
1948 3/4-Ton 5-Window Flatbed Chevrolet 34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.
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#42780 03/31/2005 4:13 PM | Joined: Feb 2004 Posts: 29,805 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,805 | That whistle is probably caused by a vacuum leak. Check the base mounting nuts for tightness, but don't break an ear off the carb by getting too energetic with the tightening. A propane torch with the gas turned on, but not lit, will help find the leak. With the engine idling,move the torch tip around close to the base flange, and any vacuum lines in the area. When the gas is picked up by the vacuum, engine speed will increase, and it might smooth out, also.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
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#42781 03/31/2005 4:56 PM | Joined: Jan 2004 Posts: 112 'Bolter | | 'Bolter Joined: Jan 2004 Posts: 112 | If you don't have a torch, starting fluid works the same way. Check the carb horn to body seal too.
Enjoy the time finding the problem and fixing it....isn't that what these old trucks are all about?
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#42782 03/31/2005 6:17 PM | Joined: Jan 2005 Posts: 164 Shop Shark | | Shop Shark Joined: Jan 2005 Posts: 164 | What Makes Carb Whistle?
It doesn't know the words? | | |
#42783 03/31/2005 9:59 PM | Joined: Oct 2001 Posts: 3,458 Extreme Gabster | | Extreme Gabster Joined: Oct 2001 Posts: 3,458 | Some carbs just whistle without there being a problem with them. It is a function of how the air flows through the venturi and throttle plate. You may be able to get it to stop by changing the air cleaner or putting a baffle in it to swirl the air to make it stop.
Paint & Body Shop moderator
A lone amateur built the Ark. A large group of professionals built the Titanic. | | |
#42784 03/31/2005 11:29 PM | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | Mono-jets are bad about leaking between the throttle body & fuel bowl. sometimes tightening the srews will fix it. Put lock washers under the heads if it doesn,t have them. You can put a new gasket in without tearing it down if you are carefull. There are 2 different gaskets for them. Make shure you use the right one & get it in correctly. Dont give up on it. They are a good carb if you get it right.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | |
#42785 04/04/2005 12:11 AM | Joined: May 2001 Posts: 1,904 'Bolter | | 'Bolter Joined: May 2001 Posts: 1,904 | Thanks guys. Maybe I solved the source of the whistle.
The Monojet was great 13 months ago but seemed to go to pot in the last couple. I think it was an intake manifold leak.
http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=2;t=008962
1948 3/4-Ton 5-Window Flatbed Chevrolet 34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.
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#42786 04/11/2005 3:03 PM | Joined: May 2001 Posts: 1,904 'Bolter | | 'Bolter Joined: May 2001 Posts: 1,904 | I replaced the manifold gaskets and everything is wonderfully normal. No whistling and the Monojet is smooooth.
CanyonAG77, the 261 just hums.
Thanks!
1948 3/4-Ton 5-Window Flatbed Chevrolet 34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.
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