Rough idle and acceleration
Thread Starter
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Cross-Country
Joined: Aug 2013
Posts: 86
Likes: 2
Rough idle and acceleration
I have a 1973 F-100, with a rebuilt 351 Cleveland in it. The truck idles rough and when I drive it, the acceleration isn't smooth.
I had this problem before the rebuild. I have new plugs (gapped), wires, coil, distributor, distributor cap, points (dwell at 26) and rotor. The carb is not new (but was rebuilt about 30,000 miles ago).
I can not get this motor to idle or run smooth. See video.
What are the top 3 or 4 things I should look at?
Alex
I had this problem before the rebuild. I have new plugs (gapped), wires, coil, distributor, distributor cap, points (dwell at 26) and rotor. The carb is not new (but was rebuilt about 30,000 miles ago).
I can not get this motor to idle or run smooth. See video.
What are the top 3 or 4 things I should look at?
Alex
Thread Starter
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Cross-Country
Joined: Aug 2013
Posts: 86
Likes: 2
I'm leaning toward buying a new/ bigger carb to add a bit of power, so I might as well, just to rule that out.
How do you feel about Pertronix no points systems? I was thinking going that route too, just to rule out points being the problem.
How do you feel about Pertronix no points systems? I was thinking going that route too, just to rule out points being the problem.
Laughing Gas
Joined: May 2006
Posts: 1,140
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From: Port Orchard Wa
Postmaster
Joined: Mar 2013
Posts: 3,066
Likes: 7
From: Over There
Pertronix is decent stuff but why bother when you can put on a better stock DSII system. Just need to grab a stock box and dizzy and wire it up. I'm not sure off the top of my head if any Clevelands had DSII stock but the dizzy is the same as any 351M/400 or 460 so any DSII dizzy from one of them will work.
Senior User
Joined: Oct 2013
Posts: 328
Likes: 2
From: Jordan Station, ON
Is the choke working properly? I had a heck of a time trying to figure out what was wrong with my 4.9L, and it ended up being the automatic choke was dead. A manual choke fixed it, and it runs like a champ
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Postmaster
Joined: Mar 2013
Posts: 3,066
Likes: 7
From: Over There
It's tuning related, tell me how you are tuning it?
Ignore that the timing is high, is it stable, I bet it isn't?
Where did you plug in the vacuum advance?
Got a vacuum gauge?
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Cross-Country
Joined: Aug 2013
Posts: 86
Likes: 2
At idle I sprayed carb cleaner all around the intake manifold and the idle did not change.
I then put a vaccum gauage on the motor. At idle it was 17 on the gauage and was consistent. At 2,000 RPM it was 22 and consistent.
Does it sound like it is tight?
It has a new distributor in it.
It is a Eldelbrock 1406 carb. I plug in the vaccum advance (looking at the front of the motor), on the lower left.
Tuning. I put new plugs in and wires and set the points to about .017. I put a dwell meter on it and kept adjusting the points until it settled at 26 degrees (the book calls for 24 to 29). The timing I did by feel. The motor is rebuilt with a RV cam. If I time it to specs, it is way to retarded, so I kept moving the timing forward until it had trouble starting and then backed it off and I found a spot where it sounded smooth and started with just a quick turn of the key.
I then put a vaccum gauage on the motor. At idle it was 17 on the gauage and was consistent. At 2,000 RPM it was 22 and consistent.
Does it sound like it is tight?
It has a new distributor in it.
It is a Eldelbrock 1406 carb. I plug in the vaccum advance (looking at the front of the motor), on the lower left.
Tuning. I put new plugs in and wires and set the points to about .017. I put a dwell meter on it and kept adjusting the points until it settled at 26 degrees (the book calls for 24 to 29). The timing I did by feel. The motor is rebuilt with a RV cam. If I time it to specs, it is way to retarded, so I kept moving the timing forward until it had trouble starting and then backed it off and I found a spot where it sounded smooth and started with just a quick turn of the key.
Moderator
Joined: Aug 2002
Posts: 6,111
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From: Southern California
At idle I sprayed carb cleaner all around the intake manifold and the idle did not change.
I then put a vaccum gauage on the motor. At idle it was 17 on the gauage and was consistent. At 2,000 RPM it was 22 and consistent.
Does it sound like it is tight?
It has a new distributor in it.
It is a Eldelbrock 1406 carb. I plug in the vaccum advance (looking at the front of the motor), on the lower left.
Tuning. I put new plugs in and wires and set the points to about .017. I put a dwell meter on it and kept adjusting the points until it settled at 26 degrees (the book calls for 24 to 29). The timing I did by feel. The motor is rebuilt with a RV cam. If I time it to specs, it is way to retarded, so I kept moving the timing forward until it had trouble starting and then backed it off and I found a spot where it sounded smooth and started with just a quick turn of the key.
I then put a vaccum gauage on the motor. At idle it was 17 on the gauage and was consistent. At 2,000 RPM it was 22 and consistent.
Does it sound like it is tight?
It has a new distributor in it.
It is a Eldelbrock 1406 carb. I plug in the vaccum advance (looking at the front of the motor), on the lower left.
Tuning. I put new plugs in and wires and set the points to about .017. I put a dwell meter on it and kept adjusting the points until it settled at 26 degrees (the book calls for 24 to 29). The timing I did by feel. The motor is rebuilt with a RV cam. If I time it to specs, it is way to retarded, so I kept moving the timing forward until it had trouble starting and then backed it off and I found a spot where it sounded smooth and started with just a quick turn of the key.
Thread Starter
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Cross-Country
Joined: Aug 2013
Posts: 86
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Tuning the carb: I screw in each screw until it slows the idle. I then back out 1/4 turn until the idle is maximum. I do that for both screws.
When I unplug the vaccum advance, it doesn't change anything, not the idle or the timing.
When I unplug the vaccum advance, it doesn't change anything, not the idle or the timing.