hard starting and erratic idling
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Senior User
Joined: Jan 2007
Posts: 243
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From: Kempton, PA!
hard starting and erratic idling
Hello all
my 1970 F-100 is having major issues. To start it, I need to crank and crank and crank, sometimes pumping the gas, othertimes holding it to the floor. I thought maybe I had a bad carb gasket (it had been slowly getting worse) so I replaced them, and now its just as hard to start, but the thing idles anywhere from 12-1300 RPM to 1800 RPM (it will change on me) whereas before I changed the gaskets, it idled around 750 RPM. I also hear a very distinct vacuum leak. I checked my carb (Holly 4 bbl) and all the vacuum ports were plugged with good plugs, so I tried to tighten down my carb more, and one of the studs started to strip. I'm getting new studs today, along with points and condenser, but I was wondering if anyone else had an idea of what is going on.
Thanks in advance
Garrett
my 1970 F-100 is having major issues. To start it, I need to crank and crank and crank, sometimes pumping the gas, othertimes holding it to the floor. I thought maybe I had a bad carb gasket (it had been slowly getting worse) so I replaced them, and now its just as hard to start, but the thing idles anywhere from 12-1300 RPM to 1800 RPM (it will change on me) whereas before I changed the gaskets, it idled around 750 RPM. I also hear a very distinct vacuum leak. I checked my carb (Holly 4 bbl) and all the vacuum ports were plugged with good plugs, so I tried to tighten down my carb more, and one of the studs started to strip. I'm getting new studs today, along with points and condenser, but I was wondering if anyone else had an idea of what is going on.
Thanks in advance
Garrett
Senior User
Joined: Jun 2009
Posts: 170
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From: Salt Lake City, UT
A vacuum leak will cause an engine to rev up because it leans out the fuel mixture. It could be coming from your carburetor itself, any of the lines attached to the vacuum tree, the power brake booster, (if you have power brakes), or from the throttle body of the carb. You can spray starting fluid, (Ether), in little bursts around these places and if the engine revs up more you have probably found the leak. Make sure the air cleaner is on so you don't get a mis reading. Good Luck!
Thread Starter
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Senior User
Joined: Jan 2007
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From: Kempton, PA!
Ok, I kept messing with it, and nothing (Haven't tried the ether thing yet) However I am just about sick of the whole points thing, and I am pretty sure something is not right in my carb either. Hopefully I can get the carb thing worked out, however, I want to get a pertronix ignition for it. Is there any suggestions on which one to get (it seems like they have multiple distributors and models, maybe i'm wrong though) and what coil would be best with it? thanks for the help guys,
Garrett
Garrett
Senior User
Joined: Jun 2009
Posts: 170
Likes: 1
From: Salt Lake City, UT
Carbs can present a serious vacuum problem. I don't know which engine you have but Autozone has a kit for the 360/390 2V Ford carb that only runs like $16.00. It has a new power valve, accelerator pump, gaskets, etc. Even if you've never done one before, with the instructions and some careful patience you should be able to clean and rebuild it in a couple of hours. If it's a different engine, then it might take longer to much longer. Rebuilding the carb should fix the vacuum leak!
If you get a Pertronix Model 1281, (360/390 V8), it is a piece of cake. Use the same cap and rotor, remove the points and condenser, screw in the module and hook the wires to the coil posts as described.....20 minutes maybe and you're on your way! They work great! But if you have a vacuum leak that remains un-fixed, you won't solve it with a Petronix. Good Luck!
If you get a Pertronix Model 1281, (360/390 V8), it is a piece of cake. Use the same cap and rotor, remove the points and condenser, screw in the module and hook the wires to the coil posts as described.....20 minutes maybe and you're on your way! They work great! But if you have a vacuum leak that remains un-fixed, you won't solve it with a Petronix. Good Luck!
Thread Starter
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Senior User
Joined: Jan 2007
Posts: 243
Likes: 1
From: Kempton, PA!
yeah sorry I should have said its a 360 but its a holly 4 bbl. Hopefully I will have time to work on it soon, but the sun is shining, therefore I am making hay
Appreciate the help
Garrett
Appreciate the help
Garrett
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Joined: Aug 2003
Posts: 7,592
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From: **** hole San Jose ca.
Have you checked the vacuum advance for a leak.? To test it suck on the hose end that goes to the carb. If you can keep sucking air, it's no good.. That Holley maybe be over you head if you've never rebuild a carb b4. I've seen some guys screw up the end float bowl gasket areas with screwdriver just trying to get them apart.Those old sticky gaskets make them a bear to get them a part.. Holley carbs our like women ,there very touchy when it comes to adjustments and the double pumper our worse with 4 adjusting screws..With a new carb gasket you don't need to tighten the studs to the point they strip, you may end up cracking the carb base plate.. What about ur choke is it manual or auto-choke and no working right.. Well got to go maybe other will add to the things to check..
