Open Headers and High Rpms

[Mopar-Charger]

I have 1973 charger running a 360 with 3 inch exhaust cutouts. It has a mild cam.

When I get up into the Rpms say about 4800-5000, it'll hit a mis-fire; performance crashes and when I move into second it'll still misfire until I get completely off the gas for about 10 seconds.

Only happens when I'm at the top of the rpms, didn't start happened until recently haven't really changed any of the ignition mainly new parts, coil, plugs, wires, etc.

When I run through my flowmasters (3 inch in 2 out) the problem only occurs at the top end of 2nd gear.

Also, is it worth it to upgrade my rods, rocker arms, and valve springs? Currently running stock

Thanks,

Jake

 

[coloradodave]

Sounds like you're running out of fuel. Check your fuel filter and do a flow volume test on the fuel pump.

 

[Mopar-Charger]

Sounds like you're running out of fuel. Check your fuel filter and do a flow volume test on the fuel pump.

Ahh thank you, I've been having a problem with the fuel pump lately. But i figured that with them, they either work or they don't?

 

[Bigal75]

Yep I agree fuel issue. When you let off, the carb bowls fill back up and then you're ok - until you beat on it again.

 

[Meep-Meep]

Open headers can affect the mixture requirements of the engine.

 

[Jeremiah]

You could try to raise the float a little bit and see if that helps. I agree that you might have a fuel delivery problem.

 

[Dako]

Open headers can affect the mixture requirements of the engine.

I remember as a teen in the early `80s watching the older guys run about 3 to 4 ft of pipe off the headers with a stripe of white shoe polish down its length. Where the shoe polish stopped discoloring from the heat is where they cut the pipe off. I understood this as 'tuning the exhaust'. As I remember, it was to optimize the back-pressure that particular motor required? Maybe one of the more dedictaed racers can add to this.

 

[HT413]

before you toss a new fuel pump on, check the fuel pump pushrod. if it's too short (worn down over the years), it wont fully actuate the fuel pump, so at open throttle the bowls empty after a couple of seconds and it stumbles. you then let off the gas and it comes back to life. it costs like $17 from comp.

 

[ZR9B]

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""Where the shoe polish stopped discoloring from the heat is where they cut the pipe off. """


that was how I was told to tune mine back in the day.