BigBrother-84 Posted January 6, 2023 Share Posted January 6, 2023 Hi Gentlemen! Following this Powerman5K's thread https://forum.garysgaragemahal.com/Mystery-hose-tp128472.html I was referred to this reading https://www.garysgaragemahal.com/chokes.html in which Gary mentions: «I should point out that if you install an aftermarket 4bbl carb, like a Holley, Edelbrock, or Demon in place of a Motorcraft 2bbl and use the factory electric choke wire you are going to have problems.». The fact is that Big Brother was born with a 351W 2V. Later, the original engine was replaced with a used 351 Cleveland 2V. I bought the truck from my father-in-law and after couple of years got serious problems with the Cleveland, so I decided to replace the engine again. Found a good 351W 4V, ran it as is during couple of years, than decided to make it rebuilt in 2015. I replaced the Motorcraft 4V carburetor with a 4V Holley last 2022. I am wondering if I should have done some modifications when Big Bro got his first 4V... How can I verify if voltage to the choke is the right one, and if not, how to correct the problem? And what kind of problem is caused by a to low voltage? Thanks! Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 6, 2023 Share Posted January 6, 2023 The first and most important question is whether the choke is working well or not. Does the engine start well in most, if not all, conditions? If so, then I wouldn't worry about how the choke is wired. If not, then it is time to figure out how it is wired. There are really just two voltages that you'll usually find at the choke: 7V and 12V. The 7V comes from the stator winding of the alternator so isn't available except when the engine is actually running, not just when the key is on. But the 12V can be available either when the engine is actually running or when the key is just on, depending on how someone wired it. So pull the wire off the choke and put your DVM on it and turn the key on. Do you get a voltage? If so, how much? Then start the engine and check again. Another check is to see where the wire goes. It may well go to the alternator and if it does it should be a white/black wire. In that case you know that you should get about 7V and only when the engine is running. And I'll bet that's what you have given that the engine originally had a 2150 carb on it. Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 6, 2023 Share Posted January 6, 2023 The first and most important question is whether the choke is working well or not. Does the engine start well in most, if not all, conditions? If so, then I wouldn't worry about how the choke is wired. If not, then it is time to figure out how it is wired. There are really just two voltages that you'll usually find at the choke: 7V and 12V. The 7V comes from the stator winding of the alternator so isn't available except when the engine is actually running, not just when the key is on. But the 12V can be available either when the engine is actually running or when the key is just on, depending on how someone wired it. So pull the wire off the choke and put your DVM on it and turn the key on. Do you get a voltage? If so, how much? Then start the engine and check again. Another check is to see where the wire goes. It may well go to the alternator and if it does it should be a white/black wire. In that case you know that you should get about 7V and only when the engine is running. And I'll bet that's what you have given that the engine originally had a 2150 carb on it. Oh, I missed the "what kinds of problems" question. The problem with having 7V on a 12V choke would be that the choke takes a long time to come off. And given that it will be a delicate balance between getting enough choke to start and having it come off fast enough not to cause the engine to be so rich it stumbles. And if you have 7V to the coil and are having problems you may be able to use the choke heater from the 2150 carb in place of the 12V heater on the Holley. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted January 6, 2023 Author Share Posted January 6, 2023 The first and most important question is whether the choke is working well or not. Does the engine start well in most, if not all, conditions? If so, then I wouldn't worry about how the choke is wired. If not, then it is time to figure out how it is wired. There are really just two voltages that you'll usually find at the choke: 7V and 12V. The 7V comes from the stator winding of the alternator so isn't available except when the engine is actually running, not just when the key is on. But the 12V can be available either when the engine is actually running or when the key is just on, depending on how someone wired it. So pull the wire off the choke and put your DVM on it and turn the key on. Do you get a voltage? If so, how much? Then start the engine and check again. Another check is to see where the wire goes. It may well go to the alternator and if it does it should be a white/black wire. In that case you know that you should get about 7V and only when the engine is running. And I'll bet that's what you have given that the engine originally had a 2150 carb on it. Gary, I wasn't expecting to get an answer tonight! Does the engine start well in most, if not all, conditions? Clearly, the answer is no. In fact, I don't remember when Big Bro started well. I am now wondering if this behavior began with the 4V engine... And more cold is the weather, more difficult is the start. I will make the verifications you are describing, and will come back. Tomorrow, not tonight. Many thanks! Link to comment Share on other sites More sharing options...
86 12 Brutus Posted January 6, 2023 Share Posted January 6, 2023 Gary, I wasn't expecting to get an answer tonight! Does the engine start well in most, if not all, conditions? Clearly, the answer is no. In fact, I don't remember when Big Bro started well. I am now wondering if this behavior began with the 4V engine... And more cold is the weather, more difficult is the start. I will make the verifications you are describing, and will come back. Tomorrow, not tonight. Many thanks! Gary is quick on the draw:-) Like gary said, 12 volts on the choke. Most of my stuff should be in today as to change out my intake on the 351L7 this weekend. Link to comment Share on other sites More sharing options...
85lebaront2 Posted January 6, 2023 Share Posted January 6, 2023 Oh, I missed the "what kinds of problems" question. The problem with having 7V on a 12V choke would be that the choke takes a long time to come off. And given that it will be a delicate balance between getting enough choke to start and having it come off fast enough not to cause the engine to be so rich it stumbles. And if you have 7V to the coil and are having problems you may be able to use the choke heater from the 2150 carb in place of the 12V heater on the Holley. Why not just use the Holley choke cover for the 4180? It is made for the 7V supply. I have one I bought to use on a friend's project that never happened (we are very much afraid covid got him as nothing has been seen or heard in well over a year). Another option (and I know it works) use a relay actuated by the 7V to switch on the 12V. Yet another, Chrysler used an oil pressure switch (NO closed by pressure) and so did GM. Chrysler's was to power the choke heater on the carbureted 4 cyl engines and GM's was to turn on the electric fuel pump on EFI engines. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted January 6, 2023 Author Share Posted January 6, 2023 Why not just use the Holley choke cover for the 4180? It is made for the 7V supply. I have one I bought to use on a friend's project that never happened (we are very much afraid covid got him as nothing has been seen or heard in well over a year). Another option (and I know it works) use a relay actuated by the 7V to switch on the 12V. Yet another, Chrysler used an oil pressure switch (NO closed by pressure) and so did GM. Chrysler's was to power the choke heater on the carbureted 4 cyl engines and GM's was to turn on the electric fuel pump on EFI engines. Ok Guys, I made a voltage test. But probably the wrong way: - Unplugged the choke wire and plugged the tester in the wire. - Other end of the tester on the battery positive pole. - Turned key on "start" position. - Got 2.75V DC (on the 10V scale). The engine wasn't started, kept the ignition key 1 second, just enough to read the voltage. Do I have to completely start the engine? Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 6, 2023 Share Posted January 6, 2023 Ok Guys, I made a voltage test. But probably the wrong way: - Unplugged the choke wire and plugged the tester in the wire. - Other end of the tester on the battery positive pole. - Turned key on "start" position. - Got 2.75V DC (on the 10V scale). The engine wasn't started, kept the ignition key 1 second, just enough to read the voltage. Do I have to completely start the engine? Jeff - You need to put the other end of the volt meter to the negative terminal of the battery. Then turn the key to Run and measure. If you have some voltage there record it. Then start the engine and record that. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted January 6, 2023 Author Share Posted January 6, 2023 Jeff - You need to put the other end of the volt meter to the negative terminal of the battery. Then turn the key to Run and measure. If you have some voltage there record it. Then start the engine and record that. Thanks Gary! Start crank = 3V Engine running = 7.8V Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 6, 2023 Share Posted January 6, 2023 Thanks Gary!Start crank = 3VEngine running = 7.8VJeff - I looks like you are seeing the stator voltage. Given that I think you have three options: Use It: You may be able to get the choke to work on that voltage, but I don't think it'll be easy or perfect. I've gotten it to work on an Edelbrock carb that expected 12V, but haven't tried it on a Holley. It sorta worked on the Eddy but it took a lot of adjusting to get it to work at all, and even then it didn't work all that well. And since you see very wide temp swings in the frozen North I don't think this will work well for you. Different Choke Heater: A heater intended for stator voltage will work. Bill suggested that the heater for a 4180 is set up for that, but I think the 4180 I have is a 12V heater. So you should look to see what yours says on it. On the other hand, I suspect the heater on the 2bbl that was on the truck was designed to work with the stator voltage and should fit the Holley. In any event, a heater that's designed to work on stator voltage will work great. Relay: Or you can install a relay that is pulled in via the 7.8V from the stator and supplies battery voltage to the 12V heater presently on the Holley. That the setup the 351HO's and 460's used and will work well. Link to comment Share on other sites More sharing options...
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