idle problem?
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From: carova beach(OBX)
idle problem?
My 351m has a holley 600cfm 4bl, and an edelbrock preformer non-egr intake. After the truck warms up it begins to idle irradically. it'll run smooth for a few seconds and then die down until it almost stalls, but only after its warm. i've checked the vac lines for any leaks and played with the timing, that helped a little. Im not sure what degree the timing should be set at, the book states what it should be at with emissions(which i have done away with)? There is also a second port on the vacuum advance that im not familiar with(not sure if its vacuum or not, so i just pluged it), so if you guys have any suggestions that would be great. thankx in advance kevin.
1980 F-250 4x4
35" swampers
1980 F-250 4x4
35" swampers
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Joined: Jan 2001
Posts: 57,025
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From: Virginia
Tighten the four large bowel screws on the front of the carb, and see if that helps. If it does a little, or it goes away for a couple of months, and then comes back, you need to tear the carb down and put new metering plate gaskets in it.
The vacuum ports. The one up high on the passenger side of the carb should be the one that the dist is hooked to. This port will not have vacuum at idle, but will if you rev the motor. The port down low is manifold vacuum, will will have vacuum all the time.
You need to set the timing by ear. After the engine is fully warm, find a long hill where you can pull the engine fairly hard in high gear. Listen for any pinging. You can advance the timing till you hear pinging during the road test, and then back off the timing till the pinging goes away. This will be the best setting for power and mileage.
Then turn the truck off and let it sit for a minute and then try to start it. If the starter seems to struggle, turn the timing back a little bit more till the starter turns the engine easy.
The vacuum ports. The one up high on the passenger side of the carb should be the one that the dist is hooked to. This port will not have vacuum at idle, but will if you rev the motor. The port down low is manifold vacuum, will will have vacuum all the time.
You need to set the timing by ear. After the engine is fully warm, find a long hill where you can pull the engine fairly hard in high gear. Listen for any pinging. You can advance the timing till you hear pinging during the road test, and then back off the timing till the pinging goes away. This will be the best setting for power and mileage.
Then turn the truck off and let it sit for a minute and then try to start it. If the starter seems to struggle, turn the timing back a little bit more till the starter turns the engine easy.
