Have a '69 Bronco with a 302 in it. Changed out the headers and it ran really well, then it started to get worse. It's defiantly coming from the passenger side.

Tightened the bolts for the headers, made sure no spark plug wires where crossing, checked the spark plugs too. Made a slight difference but still acting up.

The truck does have a little bit of carbon build up, but it's odd that it started to run rough. Little bit of back firing when it's cold, chugs a bit when cold. New problems.

I'm guessing either a cylinder or even two aren't firing right or the headers aren't properly flush somehow and it's causing back pressure problems. Plan on pulling spark plug wires once it's running to see if it's one of the cylinders. Just seems odd to have it go out after like 50 miles of swapping the headers.

If it helps, changing the headers raised the oil pressure back to normal for some reason.

Any suggestions? Anything I might have missed in checking all of this?

Thanks.

 

You still running a points ignition ? Worn points will do that everytime.

 

Hasn't been too long since the points where changed so I think we ruled that out.
We'll start there and hopefully that fixes the problem.

Thanks

 

Different brand points wear at different rates. Some don't last long at all. Points are how multiple carb setups got their bad rep, it wasn't the carbs tune changing, it was the points wearing, changing the dwell settings. Accell and Mallory used to sell different point sets with different spring rates, the spring rate determined how fast the nylon rubbing block wore, this in turn changed the gap and dwell angle. Running the wrong coil will screw with the tune too. Do yourself a favor and replace the points with an electronic unit. Save the points for after the apocalypse

 

Solved:

Found the gasket had failed on the passenger side header, cracked and broke off, not sure why (must have tightened it down in the wrong order when we put them on or something). Didn't catch it till we started it up when it was very dark and you could see fire from the cylinders.

Thanks for the help.

 

If you used the old crappy paper asbestos gaskets you didn't do anything wrong other than choosing to use em. Those are the ones that gave headers a bad rep. Notorious for leaks and burning out over time. If they lasted for long they'd get brittle then blowout