1986F150Six Posted August 31, 2020 Share Posted August 31, 2020 Jonathan - I'd be tempted to put a bit of compressed air on that port and see if it is just clogged. It is really just an opening into the low pressure area, so it wouldn't take much grease to clog it. Or, take the vacuum hose currently connected to manifold vacuum, which should have ~21" @ idle, and connect the "distributor end" of the hose to the carburetor vacuum [Venturi] port. Perhaps the greater vacuum will suck out the obstruction? Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 31, 2020 Share Posted August 31, 2020 Jonathan - I'd be tempted to put a bit of compressed air on that port and see if it is just clogged. It is really just an opening into the low pressure area, so it wouldn't take much grease to clog it. Or, take the vacuum hose currently connected to manifold vacuum, which should have ~21" @ idle, and connect the "distributor end" of the hose to the carburetor vacuum [Venturi] port. Perhaps the greater vacuum will suck out the obstruction? Certainly can't hurt anything. And, it might fix it. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 31, 2020 Share Posted August 31, 2020 Certainly can't hurt anything. And, it might fix it. Maybe squirt some carb cleaner through all the passages like suggested? Link to comment Share on other sites More sharing options...
Rembrant Posted August 31, 2020 Share Posted August 31, 2020 Question for you guys: What is the barb at the top of the carb for? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 31, 2020 Share Posted August 31, 2020 Question for you guys: What is the barb at the top of the carb for? I always thought that was the bowl vent, but I may be mistaken.. Could be ported Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 31, 2020 Share Posted August 31, 2020 Question for you guys: What is the barb at the top of the carb for? At that angle I think it is filtered air for the heated choke system. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted September 1, 2020 Share Posted September 1, 2020 At that angle I think it is filtered air for the heated choke system. The choke seems way off on the other side??? Unless you mean filtered air inlet for the choke stove? Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 1, 2020 Share Posted September 1, 2020 The choke seems way off on the other side??? Unless you mean filtered air inlet for the choke stove? Yes, filtered air that goes down to the manifold and back to the choke. Link to comment Share on other sites More sharing options...
Ford F834 Posted September 1, 2020 Author Share Posted September 1, 2020 Question for you guys: What is the barb at the top of the carb for? Cory, I believe that barb may have something to do with Evap emissions recovery or the air cleaner warm intake/emissions valves? The heat riser is on the other side of the carb and connects to the choke housing with a flare nut. Update for today: I could not blow or suck air through the vacuum hose when connected to the carb. I had sprayed the ports with carb cleaner before installing it, but I tried again (copious amounts) and no change. I tried backing out the brass barb a little in case it was bottomed out in a 90* port and blocking the passage, but that didn’t help either. I tried putting suction on it with a mightyvac, and with direct manifold vacuum but again there was no change. The port is completely plugged. The next step, I suppose, would be to remove the bottom plate of the carburetor and investigate what can be seen. Either that or try to force compressed air through the port. I did not have a fitting to try this.... but the bottom line is the truck is running very well on manifold vacuum, and I’m not going to mess with success as they say. Sorry for those who may want closure to this issue, but with the truck in daily use I’m not inclined to tear apart the new carburetor. I need the truck running and I can’t afford any more time since it is working on manifold vacuum. I drove the truck to Kingman today, mix of freeway and city driving, and it is performing about as well as I have ever had it. I would still like to replace the pickup in the recurved distributor and go back to running that instead of the stock one, but as it is right now I cannot complain. It’s running really well and I’m still impressed given the price point. Link to comment Share on other sites More sharing options...
Ford F834 Posted September 1, 2020 Author Share Posted September 1, 2020 Yes, filtered air that goes down to the manifold and back to the choke. Okay, this is making sense... although I believe it is usually missing parts on the engines I’ve seen. I’m vaguely remembering a thin tube with an orange silicone hose on the manifold set from the 4x4 donor. Link to comment Share on other sites More sharing options...
Recommended Posts