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Old 02-11-2013, 08:31 PM
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strad strad is offline
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How exactly is electric choke supposed to work?

This is a 1984 PCM 351 with the original 4160 carb and electric choke. This thing needs quite a bit of throttle to run during the initial warm up period. Once past that initial 1.5 minutes or so, it'll settle down and idle quite nicely if a bit on the high side (900 to 1000 rpms on the tach -- I need to adjust that).

I'm not convinced that the choke is operating the way I've read it's supposed to. It does operate mind you, just doesn't seem to go through the full stroke all at once or in a smooth fashion. How do I test it? Also one other thing. Do I need to re-jet this carb? it was originally run on the San Joaquin river delta (about 1-200 feet elevation I'd guess) and now I run it on Lake Mead (about 1100 feet elevation. It seems to run fine mind you.
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Old 02-11-2013, 09:15 PM
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JimN JimN is offline
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Quote:
Originally Posted by strad View Post
This is a 1984 PCM 351 with the original 4160 carb and electric choke. This thing needs quite a bit of throttle to run during the initial warm up period. Once past that initial 1.5 minutes or so, it'll settle down and idle quite nicely if a bit on the high side (900 to 1000 rpms on the tach -- I need to adjust that).

I'm not convinced that the choke is operating the way I've read it's supposed to. It does operate mind you, just doesn't seem to go through the full stroke all at once or in a smooth fashion. How do I test it? Also one other thing. Do I need to re-jet this carb? it was originally run on the San Joaquin river delta (about 1-200 feet elevation I'd guess) and now I run it on Lake Mead (about 1100 feet elevation. It seems to run fine mind you.
That elevation isn't high enough to cause problems with the fuel/air mixture, but the electric choke may need adjusting. How far does it open and at what temperature? It should open fully, regardless of the temperature but you need to indicate how far open it is when it's still cold.

Remove the throttle cable from the throttle lever and see if the idle speed drops to about 650 RPM (that's where it should be).
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Old 02-11-2013, 09:29 PM
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tockit tockit is offline
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Quote:
Originally Posted by strad View Post
This is a 1984 PCM 351 with the original 4160 carb and electric choke. This thing needs quite a bit of throttle to run during the initial warm up period. Once past that initial 1.5 minutes or so, it'll settle down and idle quite nicely if a bit on the high side (900 to 1000 rpms on the tach -- I need to adjust that).

I'm not convinced that the choke is operating the way I've read it's supposed to. It does operate mind you, just doesn't seem to go through the full stroke all at once or in a smooth fashion. How do I test it? Also one other thing. Do I need to re-jet this carb? it was originally run on the San Joaquin river delta (about 1-200 feet elevation I'd guess) and now I run it on Lake Mead (about 1100 feet elevation. It seems to run fine mind you.
Not sure how much you know about these chokes, but their supposed to be closed when cold and without power (which is the full choke position).

As soon as you turn on your ignition switch, power starts heating up the metallic coil inside that choke housing and it slowly starts opening the choke (gradually giving you less choke).

So, give you engine a few shots of throttle with ignition OFF when cold, then turn on the ignition and immediately hit the starter.

You can take your flame arrestor off and see if your choke's working properly.

If all that looks good, you may need a carburetor adjustment?
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Old 02-12-2013, 06:05 AM
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SkiDaddy SkiDaddy is offline
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What Tockit said is good advice. Also, the choke thermostat housing is adjustable and can rotate in order to adjust the position of the choke blade. If you loosen two or three screws on the choke thermostat housing, you'll be able to see what I'm talking about.
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