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Discussion Starter · #1 ·
I have a stock 68 with a 307 that was running perfectly. I put headman headers and a duel exhaust with H pipe on it last week and now it runs rough. Especially at idle. Does the timing need to be adjusted or the carb adjusted when you improve the exhaust system? It is stalling at most stops even after it is warm. Please help, trying to get this ready to go for my daughter by Monday.
 

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You may need to richen the primaries up a bit, and advance the initial timing a degree or two. Hook up a vacuum gauge to manifold vacuum port, and try adjusting the IMS screws untill you get the highest steady vacuum reading, and see if that helps at all. You may need to increase the primary main jets/rods on whatever type carb you have to richen it up. Now you can advance the initial advance also to see if that helps, just don't advance it to much. Find what the factory initial timing is and advance it a degree or two, use a timing light if you have one or can get one, you can do it by ear but, a timing light is better. Good Luck.
 

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Get all the plug wires on right. Did you burn a wire? Loss of heat to the carb, if your in the cold.
 

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You havent stated what carb youre using.Regardless,try jetting up the carb a little on the primary side(front bowl)Are you experiencing any backfire thru exhaust when you rev it up and then let off?If you are,thats a sure sign of lean misfire condition,given that everything else is mechanically sound with your motor.I have experienced my motors over the years like to lean out a little after replacing stock manifolds with headers.
 

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Get all the plug wires on right. Did you burn a wire? Loss of heat to the carb, if your in the cold.
Bending those plug wire ever so slightly can cause a problem. I live down south so,, That change wouldn't make so much a differance that it would run bad. (Maybe) Just foul the plugs a little early or it could Pre Detonate also.
 

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Discussion Starter · #11 ·
What brand of plug wires does everyone recommend. The ones I had on the car were 8mm and the ones that I almost bought today were 7mm? Is there a good site to get high quality wires that actually fit the car?
 
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