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Discussion Topic:
realistic idle for 239 w fordomatic?
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bkewin |
04-26-2012 @ 1:16 PM
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Member
Posts: 49
Joined: Dec 2011
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Hi folks, been making slow but steady progress on the 53 f100. got a carb rebuild which took care of a few little issues, like rocking and rolling the whole truck at idle, and a blip in the vacuum guage. (my old vacuum guage was lying to me by 10 inches, but the blip was legit) maybe I had a vacuum leak that popping the carb on and off cleaned up. I turned the idle speed screw out so it wasn't in the picture. cold, I turned the idle mix screws all the way in and backed them out a complete turn. full choke start and once warmed up put the choke in and did the routine of scr*w*ng the idle mix in till she stumbled and back out to smooth. repeated on both sides. she starts and runs pretty smoothly. I set the idle speed to 425 with my 20 dollar 12v dwell tach but she was stalling at stop signs so I increased the idle a bit. My question is, "how important is the 425 idle rpm"? I'm waiting on my mail order timing light and remote starter switch. but mostly starting and running like she does the timing can't be that far off. Sometimes she idles with 14inches of vacuum and others 16. Seems like if she is warm, there is less idle vacuum. well, Thanks, Bill
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supereal |
04-27-2012 @ 10:09 AM
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Senior
Posts: 6819
Joined: Oct 2009
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Bill: The ideal idle speed is given in my manuals as 415-425 for 8 cylinder trucks, and 450-460 for the sixes. That is a bit slow, compared to manual transmission trucks, which we customarily set at or above 500 rpm at idle. The lower speed was to prevent creep and harsh engagements and shifts with the automatic. In order to reduce stalling, the system requires a "dashpot" that slowly allows the throttle to return to idle. If your truck doesn't have one, or yours is weak, that is the likely reason it stalls at stop signs
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TomO |
04-27-2012 @ 10:35 AM
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Senior
Posts: 7263
Joined: Oct 2009
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I agree with Supereal as the dashpot might be the culprit. Your timing could also be off and that is why you are getting such low vacuum readings. You should be able to set the idle at 450 without having excessive creep. Plug all vacuum connections and recheck your vacuum. If it is still low, check for leaks around the carburetor. If there are no vacuum leaks, mark the distributor position and try adjusting the timing a little while reading the vacuum gauge for the highest reading and then back off the timing slightly (About 1 degree). Reconnect your vacuum hoses and give it a try.
Tom
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bkewin |
04-27-2012 @ 12:33 PM
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Member
Posts: 49
Joined: Dec 2011
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you fellows are the best. I sure appreciate the advice. I'll give that vacuum timing hint tonight. Thanks again Bill
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alanwoodieman |
04-29-2012 @ 7:26 PM
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Senior
Posts: 868
Joined: Oct 2009
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look to see if your trans has a throttle rod going from the eccelerator linkage back to the trans-if it does adjust this length. The trans is still "in gear" and will try to creep if this has not been set correctly and will also affect the idle speed
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bkewin |
04-30-2012 @ 9:50 AM
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Member
Posts: 49
Joined: Dec 2011
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Oh Joy. I have noticed this creeping I think. Did the u-joints over the weekend and neglected everything else. I'm waiting for an extension housing seal before i button everything up. I've got a little rust on the drive shaft yoke. While I think this will do for a while, if it eats seals, is there a source for replacements out there? Thanks.
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TomO |
05-01-2012 @ 7:48 AM
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Senior
Posts: 7263
Joined: Oct 2009
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Try polishing the drive shaft yoke with emery paper followed by crocus cloth. If you have lots of deep pits, look for another yoke.
Tom
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bkewin |
05-02-2012 @ 1:02 PM
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Member
Posts: 49
Joined: Dec 2011
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That's kind of funny, I sanded and oiled and sanded for about 30 minutes and saw a bit of crocus cloth hanging out of my sanding odds and ends drawer. I can't remember how it came to be there but it worked a treat. Couple of tiny pits in a ring and two or three nicks from some careless so and so with a hammer up close to the knuckle. Thanks for the input.
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supereal |
05-02-2012 @ 2:33 PM
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Senior
Posts: 6819
Joined: Oct 2009
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The seals are available. The outside diameter should be 2.376 for your pickup. A later type, beginning in '56, mweasures 2.509 OD. Be sure to use the correct driver when installing them. Almost all extension housing seals seep a bit. This keeps the shank of the yoke lubed as it moves on the shaft. A badly worn yoke will show a pronounced wear ring that can't be polished away.
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bkewin |
05-03-2012 @ 6:30 AM
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Member
Posts: 49
Joined: Dec 2011
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I'm having a hrd time finding any special tools for the extension housing seal. I found an extension housing bushing tool for an aod, is there anyplace that carries either of these? my online searches are coming up dry. Napa has the seals and the bushing should it come to that, but not finding tools. Thanks, bill
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