I am trying to figure out how to get my car to start better after the engine is warm and it’s sat for more than 5 or 10 minutes. Right now it fires right up with a 1/2 push of the gas pedal when it’s cold or if I re-start it immediately after I shut it off when the engine is warm, but if I let it sit for anything more than 5 or 10 minutes I have to crank on it for a little while and push the gas down to get it to start.
My first vehicle was a '72 F-250 390 with the factory 2 barrel on it. My grandparent’s neighbor is a mechanic, he rebuilt the carb for us and you barely had to engage the starter and it would start immediately, no matter how long it sat, I loved that! I would like to get my Cougar to do that. It has a single fuel inlet Holley on it, I’m not sure of the model #, but it is an electric choke carb and I think the previous owner said it’s 600 or maybe 650 cfm.
Does anyone know what I can adjust to make it so I just have to tap the key to get it to start or might it need a full rebuild?
When you shut it off hot (for the problem to occur), take the air cleaner off and look at the boosters in the venturi’s (for a minute or two) to see if fuel is dripping from them down onto the butterfly plates (and into the intake from there). If yes, this is likely the source of your hot start problem.
It could be a number of things. As Bob stated you can be experiencing “boiling fuel”. I had the same issue with my 67 390 and it turned out to be a cable issue. I upgraded my cables and battery to a Optima Red. It has 1000 CCA and I have not had any cranking issues when hot since addressing those two issues.
Steven
Thanks for the reply. It cranks at the same speed between the engine being hot and cold. I am going to take a look at what Bob mentioned and post what I observe.
I also experienced “boiling fuel” with hot starts possible only with long cranking while flooring/pumping the gas pedal, in my case this effect was related to overheating.
I’m having the same issue with my Edelbrock carb, I think it’s heatsoak boiling the fuel. Ethanol lowers the boiling point of fuel so this is more of a problem these days than it used to be. I found a lot of people having good luck with these: https://www.summitracing.com/parts/edl-9265/overview/
My 67 390 is a .030 motor factory holley repro factory battery which are junk and repro factory battery cables which are very thin and a factory starter, with this set up I never had an issue with starting. If all of your parts are in good condition and in proper tune you should be good. Also 10% ethanol unleaded fuel.
You guys who said fuel percolation were right! Last night after having the car out driving for about 1.5 hours. I popped the air cleaner off as soon as I got it in the garage, got my shop light out, stared down the neck of the carb and after about 3 minutes fuel started sporadicly pulsing out of the top of the carb down onto the butterflys. I guess at this point it would be best to do as mfc1333 suggested and get the edelbrock spacer?
When I was looking at the carb last night I found a number of 11761 on it. I did a quick google search and it looks like this is a 600cfm carb with vacuum secondaries, my engine is a 351W by the way. I have been thinking the secondaries aren’t opening on the carb because I don’t hear that big rush of air like I do in my Jeep that has an Edelbrock 600cfm with vacuum secondaries when I go WOT. Last night when the car was running I manually opened the throttle to WOT and didn’t see the secondaries opening. Should i be able to see them opening or does the car have to be under a load? I can start a separate thread for this if that is preferred.
You might try lowering the float a little to help with the first problem, and the car should be under a load, if you hold the carb at WOT long enough for the secondaries to start opening you might damage something.
To verify proper operation of the secondaries, wrap a bread tie on the actuator rod just below the diaphragm, then go drive up an on-ramp or some other spot where you can safely run at wide open throttle for ten seconds or so. This video explains what you’re looking for: https://www.youtube.com/watch?v=kXUFwaWo_rQ
I had the car out last night and wrapped a zip tie around the actuator rod and did a few tests. The secondaries are opening, but I don’t think they are opening all the way. I did one test where I held it to the floor from a dead stop and it pushed the zip tie down pretty far, but I don’t think all the way. For the next test I was doing about 35mph and held it to the floor for about 5-6 seconds. After I got home from the second test I looked at the zip tie, it moved down some, but not much. I marked the top of the zip tie with a fine tip sharpie than manually opened the secondaries all the way and you can see the difference in the picture. I guess I need to find a softer spring for it to make the secondaries open more/quicker?
Holley used to sell a kit with several color coded springs. I swapped them out and ran the same 1/8th mile flat out to see what the difference was. When you go too soft it actually slows down. Once I had my full throttle response nailed I tried regular driving. Look for a bog when you tip into the throttle. The worst side effect I had was driving on the highway at say 3000 RPM. When the secondaries are open the gas mileage dropped like a rock. As in 6 miles to the gallon tops.
I installed the Edelbrock heat spacer a couple days ago and unfortunately it is still boiling the fuel I let it sit for a few minutes and it wouldn’t key right up. Yesterday I had it out, let it get up to temp, popped off the air cleaner and started at, about the same as before, after about 2 to 3 minutes I watched the fuel percolate out and run down onto the butterflies.
I think the next step is to do as another member posted and attempt to lower the float level. This seems logical, but I’ve never done it before. Does anyone know if I have to bend the float down slightly or if I stick a ruler in the float bowl and lower by a certain amount and if so how much? I’m going to google what the procedure is to get to and set the floats.
I think you are onto something here. I researched setting the floats in a Holley carb, much easier than I expected, pulled the screw out of the side of the float bowl, the fuel should be at the bottom of the threads, it came gushing out and drained for a while. I re-adjusted, got car hot, let sit, started after 3 mins, tried again, but after for 10 mins had long crank again, drove car around, when I got home I watched it percolate fuel after 3 mins then sporadically the next 2 mins. I lowered float level again so we’ll see next time car goes out.
You are not running an electric fuel pump by chance, if not this is not a cure, but when you go to start the car after it sets after driving, you can hold the gas pedal to the floor, and it will start quicker, don’t pump it just hold it down. Let me know how this works.
I let it sit for a few minutes and it wouldn’t key right up. Yesterday I had it out, let it get up to temp, popped off the air cleaner and started at, about the same as before, after about 2 to 3 minutes I watched the fuel percolate out and run down onto the butterflies.