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#13118 04/22/2004 6:31 PM | Joined: Nov 2002 Posts: 55 Member | | Member Joined: Nov 2002 Posts: 55 | The 235 in my 55.2 has a Rochester Model BC carb; it's the type with an automatic choke. I'm trying to figure out why it seems to run rich.
While fooling around with it last night, I observed that if I take off the air cleaner while the engine is running, the idle speed slows down. Putting it back on causes idle speed to go back up. The air cleaner is not stock. It's a paper element that doesn't seem to have much resistance to air flow (based on my scientific test of holding it up to my mouth and blowing through it).
Is this normal? Or is this air cleaner choking the engine and could this be causing the engine to run rich?
Thanks. | | |
#13119 04/22/2004 6:39 PM | Joined: Oct 2001 Posts: 3,458 Extreme Gabster | | Extreme Gabster Joined: Oct 2001 Posts: 3,458 | What size is the air cleaner? The little doughnut size air cleaners don't flow enough air for a 235. I use two stacked on each other for my 261.
You should calibrate your carburator with the air cleaner in place. It sounds like your idle mixture needs adjustment.
Paint & Body Shop moderator
A lone amateur built the Ark. A large group of professionals built the Titanic. | | |
#13120 04/22/2004 6:56 PM | Joined: Nov 2002 Posts: 2,766 Carburetion specialist | | Carburetion specialist Joined: Nov 2002 Posts: 2,766 | If the air cleaner is the proper size for the engine, there will be no change in RPM with the air cleaner on or off.
Jon.
Good carburetion is fuelish hot airThe most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes!The Carburetor Shop | | |
#13121 04/22/2004 7:12 PM | Joined: Nov 2002 Posts: 55 Member | | Member Joined: Nov 2002 Posts: 55 | Thanks for the quick replies. If there is not supposed to be an RPM change with air cleaner off, then mine is probably too small. It is a "donut." It's about 4" in diameter. | | |
#13122 07/12/2004 9:51 PM | Joined: Apr 2004 Posts: 33 Member | | Member Joined: Apr 2004 Posts: 33 | does anyone know where i can get my hands on a good air filter, mine is also the small kind but it doesn't even fit right, i got it from napa and wrapped a bunch of duct tape around the top of the carb and cranked the hose clamp down tight.
oh and i have a 235 with a single barrel roch. carb | | |
#13123 07/13/2004 1:17 AM | Joined: Oct 2003 Posts: 124 Member | | Member Joined: Oct 2003 Posts: 124 | I like my stock, oil-bath air filter. Designed for the job, and if you want to dress it up - new paint and decals look great.
I see these on eBay often, and they don't cost very much. Plan on a clean up - kerosene soak (per the manual) for a few days, and a new fill with oil. | | |
#13124 07/13/2004 1:25 AM | Joined: Apr 2004 Posts: 33 Member | | Member Joined: Apr 2004 Posts: 33 | | | |
#13125 07/16/2004 3:03 PM | Joined: Dec 2000 Posts: 506 Shop Shark | | Shop Shark Joined: Dec 2000 Posts: 506 | If you want to use the chrome top and bottom of the little 4" filter and don't mind that the filter sticks out try a Napa Gold #6272 air filter.
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