why is my engine popping through exhuast....?

[MikeMacCham]

I have a 68 charger which was originally a 318, at some point it was converted to a 440 (not sure what they got it out of or what year, i think 73') When I got the car we replaced the cam shaft which had a frozen lifter and that lobe of the cam had been worn down. The engine was advanced 4*, we set that back to 0*. Then there was a issue with the radiator, so we got that fixed, we were trying a new carberator on the car to see which one I wanted to buy and we noticed the engine ran fine but when the engine reved it popped. It was running a little weak before we traded the carberator out, but not this bad. What we have done to try to fix it:

put the first carberator back on (still has problem)
replaced the distributer cap, rotar and spark plug wires
new ignition module

ANY ideas would help, thanks guys!

[firefighter3931]

Mike, first thing to check for is vacuum leaks. How does the carb base gasket look ?


Ron

[jg68]

Timing, Timing, Timing, if you set it at 0* on the tab, its way too low, set it at around 10* Advanced at idle with the vacuum advance plugged, i'll bet it runs alot better & stops popping

[deputycrawford]

I agree with firefighter. I would check for vacuum leaks. Take a propane torch. Don't light it; but turn on the gas. Run it around the carb base, intake, vacuum lines and anywhere you think could cause a vacuum leak. Put it really close to the object you are testing while the engine is running. If the engine revs up at a certain object, like the base gasket, you have found your vacuum leak. Replace gasket and you might have fixed the problem. Start there and get back to us.

[MikeMacCham]

I EFF'N Love you guys, will do today and thanks. Hey Firefighter 3931, what department do you work for? I'm with LAFD.

[firefighter3931]

Mike, i'm in Ottawa, Ontario, Canada. The freakin frozen North !!! 

Let us know what you find. 



Ron

[MikeMacCham]

 ok 80% fixed, the vacume fitting for the head lights was unplugged, but it is still firing in the exhuast...
and timing is 12* initial, about 40 total

[68chrgrwife]

I would have said the vacumm advance too...I had that problem with my chally, we just made it stay open at all times and it stopped popping.

[MikeMacCham]

we talked to a guy that said it may be a fuel issue (like not enough)since its a bored out 440, that kinda makes sence since the problem chaned w/ different carbertors, i'll keep ya posted

[MikeMacCham]

that actually made it worse, we took  out a spark plug and it was black/ to rich, so we tryed a smaller fuel jet and that didn't work either. I am replacing the spark plugs and distributer pick up just in case that works, if not then we are going to take it to a shop and put it on a scope....

[firefighter3931]

Mike,

Pull a plug wire and ground it to the engine while cranking the engine over. Look at the arcing spark for color....dull orange means your ignition system is weak. Whiteish-blue means the spark is strong. You might have a weak ignition system.

Double check the plug wires as well....it's not uncommon to mix up the #5 & #7 wires when installing new leads. 



Ron

[jg68]

Mike,

Pull a plug wire and ground it to the engine while cranking the engine over. Look at the arcing spark for color....dull orange means your ignition system is weak. Whiteish-blue means the spark is strong. You might have a weak ignition system.

Double check the plug wires as well....it's not uncommon to mix up the #5 & #7 wires when installing new leads. 



Ron

[pb24]

Hey Mike I work for the LAFD. what station do you work at?

[MikeMacCham]

seemed like some orange, some blue...

[MikeMacCham]

I changed the spark plugs and it seems to run alot smother... didn't seem to pop. One of the spark plugs had no gap at all
Now the question is should I put the thick fuel line back in and advance the timing? Will it run better? I think it's at like advanced 20 right now, and the jet fuel size was 71? should it be bigger for a bored 440 w/ a 750 cfm carb?