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| | | | Joined: Nov 2005 Posts: 116 Wrench Fetcher | | Wrench Fetcher Joined: Nov 2005 Posts: 116 | I have never been able to get this old beast to run right. She has a flat spot just off idle and acts like its running lean since the idle speed improves if I restrict air by placing my hand over the carb. I rebuilt it and raised the float level to no avail. Although, standing next to it at idle it smells rich. I replaced the accelerator pump which helped slightly but it still has a slight flat spot.
The carb is a Q-jet 7040511 which is mounted to an adaptor plate so, I assume this is not the stock carb.
Timing advanced seems to help but then it gets difficult to start when hot. I'm wondering if the advance mech in the dist might be stuck.
Any suggestions? | | | | | Joined: Nov 2002 Posts: 2,765 Carburetion specialist | | Carburetion specialist Joined: Nov 2002 Posts: 2,765 | 7040511 - California smog emissions (LEAN) Chevrolet 350.
Spread-bore to square-bore adapters are for snake-oil salesmen ;), not for engines.
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 | | | | | Joined: Nov 2005 Posts: 116 Wrench Fetcher | | Wrench Fetcher Joined: Nov 2005 Posts: 116 | Thats what I was afraid of.
Another previous owner hack!!!
| | | | | Joined: Nov 2005 Posts: 116 Wrench Fetcher | | Wrench Fetcher Joined: Nov 2005 Posts: 116 | Jon, What carb belongs on this 366? | | | | | Joined: Nov 2002 Posts: 2,765 Carburetion specialist | | Carburetion specialist Joined: Nov 2002 Posts: 2,765 |
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 | | | | | Joined: Nov 2005 Posts: 116 Wrench Fetcher | | Wrench Fetcher Joined: Nov 2005 Posts: 116 | Thanks Jon.
Based on your sig I'll be "I'll be walking in the spouse's shoes" and modifying the wrong carb.
I think I just need more accelerator pump. I have the rod in the max throw position now so, I may just have to live with it. | | | | | Joined: Mar 2004 Posts: 6,214 'Bolter | | 'Bolter Joined: Mar 2004 Posts: 6,214 | It's easy to test the distributor advance...hook a timing light up to #1 plug wire, rev up the engine and see if the timing mark moves. Mike B  | | | | | Joined: Nov 2005 Posts: 116 Wrench Fetcher | | Wrench Fetcher Joined: Nov 2005 Posts: 116 | The vacuum advance hose may not even be connected to the correct place. And, this thing has an HEI dist. Was the HEI around in 1970?
I hope I can find my timing light. It's been a while since I needed to use it.
Between the mice and rats chewing wires and all the hacks from previous owners it may take a while to get it running right.
Nothing like having a big rat run across your foot while checking that flat spot off idle.
| | | | | Joined: Sep 2011 Posts: 1,453 'Bolter | | 'Bolter Joined: Sep 2011 Posts: 1,453 | And, this thing has an HEI dist. Was the HEI around in 1970? HEI came out in 1975 366 wouldn't have had a vacuum advance, only mechanical.
BC
1960 Chevy C10 driver 261 T5 4.10 dana 44 power loc
1949 GMC 250 project in waiting
1960 C60 pasture art
Retired GM dealer tech. 1980 - 2022
| | | | | Joined: Nov 2005 Posts: 116 Wrench Fetcher | | Wrench Fetcher Joined: Nov 2005 Posts: 116 | Metering rods and retaining piece looked good.
I believe its a matter of not having the correct carb. Too much vacuum drop and not enough fuel just off idle. Otherwise, it runs rich since I tried to compensate.
I can live with it since it's not too bad now. In the meantime I'm searching for the correct Holley carb. | | | | | Joined: Nov 2005 Posts: 116 Wrench Fetcher | | Wrench Fetcher Joined: Nov 2005 Posts: 116 | Thanks to Sim for sending me the correct Holley carb for the 366. I should have it installed this weekend and see how she runs.
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