BigBrother-84 Posted November 22, 2023 Share Posted November 22, 2023 Hi gentlemen! Cold weather is coming back, we’re waking up under freezing point every morning since almost two weeks now. 3" of snow yesterday night. Since my GMC Terrain is at dealer’s garage for a week now (they are waiting for a part), I use Big Brother as my daily drive vehicle. Cold start: • After pressing the pedal to the floor and slowly leaving it up, get off my feet of it and turn the ignition key, he starts instantly. • He runs smoothly for 4-5 seconds, then the engine begins to run roughly. At lot of exhaust smoke. • Runs this way for the time it takes to warm enough so the choke flap begins to open. • Then, almost instantly, no more “rough running”, runs smooth and RPM are going up as the choke opens, this until 100% opened. • After couple of seconds lettings this high RPM going on, I touch the pedal and the engine goes down at its normal RPM (around 750-800). Question: Why this rough behavior chapter until the choke begins to open? Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 22, 2023 Share Posted November 22, 2023 You have the original carb, the Holley 4180C, right. If so it sounds like you have the choke plate is closing too far. I say that because you said that the smoke starts after 4 to 5 seconds, which I would think is before the choke heater could possibly be expected to bring the choke off. But the process to adjust the choke closing, aka "choke plate pulldown", isn't straightforward, as shown in the snippet below from Ford's service manual on that carb. That being the case I'd back off one notch on the choke setting. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted November 22, 2023 Author Share Posted November 22, 2023 You have the original carb, the Holley 4180C, right. If so it sounds like you have the choke plate is closing too far. Gary, I replaced Big Bro’s carb not so long ago. This new Holley carb has a “partial choke flap” design, as I already posted in this thread. Could this has to see with my «rough running» cold start? But the process to adjust the choke closing, aka "choke plate pulldown", isn't straightforward, as shown in the snippet below from Ford's service manual on that carb. That being the case I'd back off one notch on the choke setting. Can I apply these instructions to my “partial choke flap” carb? Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 22, 2023 Share Posted November 22, 2023 You have the original carb, the Holley 4180C, right. If so it sounds like you have the choke plate is closing too far. Gary, I replaced Big Bro’s carb not so long ago. This new Holley carb has a “partial choke flap” design, as I already posted in this thread. Could this has to see with my «rough running» cold start? But the process to adjust the choke closing, aka "choke plate pulldown", isn't straightforward, as shown in the snippet below from Ford's service manual on that carb. That being the case I'd back off one notch on the choke setting. Can I apply these instructions to my “partial choke flap” carb? Oops, I forgot that. I doubt you can use those instructions on the different carb. Bill's the guy to ask how to adjust that part on that carb. But I'd still back off one notch on the choke cap. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted November 22, 2023 Author Share Posted November 22, 2023 But I'd still back off one notch on the choke cap. Well, I said to myself «Why not give a try, it won't kill anybody». 1- Cold position, before any move: 2- After depressing the pedal ("partial" choke flap 100% closed): 3- After ignition, when it began to "rough run" after the initial 4-5 seconds, I forced the opening a little bit with a screwdriver. Looks that it helps, the engine runs smoother: 4- I stopped immediately the engine (so it stays cold), and I decided to modify the position of the choke heater, turning it a little bit clockwise. This places the cold flap position slightly opened: New cold ignition, the engine starts immediately and after the initial 4-5 seconds, the engine continues to run smoothly. "Rough run" seems to be gone. I'll test this setting couple of cold mornings before declaring the issue solved. Gary, you had a good intuition! Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 22, 2023 Share Posted November 22, 2023 But I'd still back off one notch on the choke cap. Well, I said to myself «Why not give a try, it won't kill anybody». 1- Cold position, before any move: 2- After depressing the pedal ("partial" choke flap 100% closed): 3- After ignition, when it began to "rough run" after the initial 4-5 seconds, I forced the opening a little bit with a screwdriver. Looks that it helps, the engine runs smoother: 4- I stopped immediately the engine (so it stays cold), and I decided to modify the position of the choke heater, turning it a little bit clockwise. This places the cold flap position slightly opened: New cold ignition, the engine starts immediately and after the initial 4-5 seconds, the engine continues to run smoothly. "Rough run" seems to be gone. I'll test this setting couple of cold mornings before declaring the issue solved. Gary, you had a good intuition! Wonderful! Link to comment Share on other sites More sharing options...
FordFETruck Posted November 26, 2023 Share Posted November 26, 2023 Wonderful! Those newer Holley's without the choke pull off and the slotted choke in my experience are horrible and it was just a way to save cost on manufacturing at the expense of a poorly running engine during warmup in most cases. I have a quick fuel SS780VS on a Ford 445 FE stroker that is the same way, and it was so terrible trying to get it to run right on choke I converted it to manual choke. I'll never buy another automatic choke Holley that's like that. The Summit racing 4010 series carburetors still come with choke pull off, I put the 7 volt Motorcraft choke thermostat on those wired to the stator wire on the alternator and they start and run nearly as well as EFI. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted November 26, 2023 Author Share Posted November 26, 2023 Those newer Holley's without the choke pull off and the slotted choke in my experience are horrible and it was just a way to save cost on manufacturing at the expense of a poorly running engine during warmup in most cases. I have a quick fuel SS780VS on a Ford 445 FE stroker that is the same way, and it was so terrible trying to get it to run right on choke I converted it to manual choke. I'll never buy another automatic choke Holley that's like that. The Summit racing 4010 series carburetors still come with choke pull off, I put the 7 volt Motorcraft choke thermostat on those wired to the stator wire on the alternator and they start and run nearly as well as EFI. I already swapped the original 7V thermostat to this new carb. But, if I still have cold start issue with this carb, I begin to think about sending my original carb (which I still have) to a specialist, for a complete rebuild/restoration… 🧐 Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted November 26, 2023 Share Posted November 26, 2023 I already swapped the original 7V thermostat to this new carb. But, if I still have cold start issue with this carb, I begin to think about sending my original carb (which I still have) to a specialist, for a complete rebuild/restoration… 🧐 The 4180 isn't difficult to rebuild but you absolutely need to get the correct 3-1346 kit. A generic 4160 kit won't do. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted November 26, 2023 Author Share Posted November 26, 2023 The 4180 isn't difficult to rebuild but you absolutely need to get the correct 3-1346 kit. A generic 4160 kit won't do. Link to comment Share on other sites More sharing options...
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