302 rough idle
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Joined: Jul 1999
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302 rough idle
I have a 302 from a 74 van with a rough idle. I noticed after installing new headers that the paint on cylinders number 2 and 7 is not burned off like the rest of the pipes. I have changed plugs and plug wires but the problem persists.
With it at idle I can pull the number 7 wire from the dist. cap and nothing changes. Also I have no vacume at the hose to the distributor advance can.
Next step is a new dist. cap and take it from there. Could it be a bad carb. making the 2 and 7 cylinders not run right Also the lable on the valve cover says to run at 6 degrees advance? I thought it was supposed to be ten degrees. HELP
With it at idle I can pull the number 7 wire from the dist. cap and nothing changes. Also I have no vacume at the hose to the distributor advance can.
Next step is a new dist. cap and take it from there. Could it be a bad carb. making the 2 and 7 cylinders not run right Also the lable on the valve cover says to run at 6 degrees advance? I thought it was supposed to be ten degrees. HELP
Posting Guru
Joined: Jun 1999
Posts: 1,525
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302 rough idle
Yes,checking the cap and rotor is a good idea,but what did the plugs in those two cylinders look like when you removed them? Also,when you pulled the wire off, did you hear {or feel-ouch!}the spark jumping the gap,indicating spark was available? Finally,you should have a compression check done on all 8 for the sake of it.Sometimes it might just be stuck rings that can be loosened up by an overnight soaking with a product like B-12 Liquid Carb Clean poured down the cylinder.Be sure to crank the engine with the plug[s] removed to blowout any liquid left over in the morning.Here are 2 off the wall things I have seen that will drive you crazy; broken reluctor teeth & a module that had a mind of it's own,effectively taking out a cylinder in the firing order at random!Good luck.
Phillip
Phillip
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Joined: Aug 2008
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From: Manistee, MI
Rough idle solution
Hey folks if you have these symptoms before you go through a lot of trouble looking for an electrical problem CHECK THE EGR VALVE!!!!!!!!!!!!!!!!!!!!!!!!!!
I recently rebuilt a 302 and had a rough idle & could pull the #7 wire off with no change, the EGR valve was stuck open, tapped the vale to get it to shut and the problem went away!
I recently rebuilt a 302 and had a rough idle & could pull the #7 wire off with no change, the EGR valve was stuck open, tapped the vale to get it to shut and the problem went away!
New User
Joined: Jul 2008
Posts: 16
Likes: 0
Hey folks if you have these symptoms before you go through a lot of trouble looking for an electrical problem CHECK THE EGR VALVE!!!!!!!!!!!!!!!!!!!!!!!!!!
I recently rebuilt a 302 and had a rough idle & could pull the #7 wire off with no change, the EGR valve was stuck open, tapped the vale to get it to shut and the problem went away!
I recently rebuilt a 302 and had a rough idle & could pull the #7 wire off with no change, the EGR valve was stuck open, tapped the vale to get it to shut and the problem went away!
But like someone else mentioned, do a compression check and read the plugs.
