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#49775 08/31/2005 3:34 PM | Joined: May 2001 Posts: 1,907 'Bolter | | 'Bolter Joined: May 2001 Posts: 1,907 | It was in the high 30's this morning and the 261 started just fine and ran without choking its Rochester Monojet carb. Is this a sign that the idle is set a bit too rich?
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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#49776 08/31/2005 5:42 PM | Joined: Jul 2005 Posts: 1,158 Shop Shark | | Shop Shark Joined: Jul 2005 Posts: 1,158 | You started it cold, right?
It sounds like you're running a bit rich.
I don't kow your carb, but if it's like mine, there is a mixture screw, and an idle screw. You probably aren't going to need to touch the idle, just the mixture. | | |
#49777 08/31/2005 10:22 PM | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | It,s more likely the main jet is too large. It should hesitate on acceleration when cold without using the choke & run good when warmed up.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | |
#49778 09/01/2005 12:35 AM | Joined: Aug 2005 Posts: 8 New Guy | | New Guy Joined: Aug 2005 Posts: 8 | One thing that might be causing the carb to run rich is the float. Sometimes the float(originally made of brass) starts to leak which allows the float to sink lower and lower until it causes the needle valve to allow more fuel to flow into the manifold than is necesary. You might also check the float setting, if the setting is wrong it can cause the same problem. O'reilly's still has some floats for the old carburetors and they are very reasonably priced. | | |
#49779 09/01/2005 3:15 PM | Joined: May 2001 Posts: 1,907 'Bolter | | 'Bolter Joined: May 2001 Posts: 1,907 | The Monojet has a metering rod sitting in the main jet. When you step on the gas, the rod is raised. I'll bet it's adjusted a bit too high which makes the jet, in effect, too large. It doesn't hestitate cold in the morning when I accelerate w/o choke.
Then I'll look at the idle mixture adjustment. There are many turns required to go from the chuggings of too lean and too rich. I read where it sould be set just this side of too rich.
I have a Carter YF in the basement but the Monojet hasn't given me many problems.
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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