HELP!! 340-5 speed problem(s)(s)(s)(s)

[cdummer43]

Alright gents/and ladies, have a bit of a dilemma. Little back story, was hot rodding in my 74 Challenger (340-5 speed) a couple of weeks ago. And needless to say at about 90mph just rolling into fifth gear my car stopped running, completely dead. Found out it was an inline fuse i had put in the ignition/power wire on the column. I replaced the fuse on the side of the road and limped it home. Checked all of the wiring (twice) that may have caused the fuse to pop and everything is up to par.

Ever since then my car runs like poop. Every time I try to gouge on it in the low end gears it back fires/falls on its face and then gets up and goes. Never had this problem before. Especially in fifth gear the car back fires with the very minute acceleration, almost like it is on demand to make it back fire when you press on the gas. Also in fifth gear now, after the back fire, it almost feels as though the motor is shuddering and vibrates like it has never before. The shuddering only happens in fifth gear. And I know you are thinking, "duh dude, too low of RPM," but that is not the case either I have tried it at low RPM's and at higher RPM's with the same results of back firing and shuddering.

As I sit here contemplating what the problem may be, I have what feels as though a laundry list of things (fuel, vacuum leak, something with the rotating assembly, ignition, etc.) that could be causing this. The charging system is working properly, fuel pressure is well, all plugs look good, no fluid leaks (externally at least), oil pressure is well, and oil level is well.

So, I am wondering if someone has ever experienced this problem before in a similar setup, or something close to mine, and how you may have sought out to fix your problems. Your help will be beyond greatly appreciated, although I may just rip the motor out and throw a new power plant in (one that has a nice warranty).

Thanks for taking the time to read this.

 

[moparleo]

Time for some basic diagnostics. We need air/fuel, compression/timing. Using a timing light , start the engine and let it idle. Is it smooth ?What does the timing mark do ? Steady or moving back and forth? Now raise the rpms and hold it at about 2500 rpms, what does the timing mark do now ? Still smooth ? by the way how are the water temp and oil pressure doing ? Every thing still smooth and perfect ? Or has any thing popped up yet ?

 

[moper]

What type of ignition system do you have? How is it wired in?

 

[sfort]

I had a strange thing happen to me a couple years ago. Filled up with gas and stopped at a stop sign a mile away. Engine died. Got it started and it run very poorly and did not want to idle. I thought "bad gas" and started working the issue from that angle. To make a long story short the metal canister fuel filter came apart and dumped all its trash into the carb. Rebuilt the carb and all OK. I hope that helps!

 

[cdummer43]

What type of ignition system do you have? How is it wired in?

MSD 6 ignition box with the basic electronic ignition distributor.

 

[cdummer43]

I had a strange thing happen to me a couple years ago. Filled up with gas and stopped at a stop sign a mile away. Engine died. Got it started and it run very poorly and did not want to idle. I thought "bad gas" and started working the issue from that angle. To make a long story short the metal canister fuel filter came apart and dumped all its trash into the carb. Rebuilt the carb and all OK. I hope that helps!

I was thinking it is something with either the fuel or the ignition. I still haven't played with it all that much because I have a history of tearing the whole car apart to find a problem and it is something really easy and glaring that I over looked! I was going to pull the car and put new carb-manifold gaskets on to see if there is a small vacuum leak there, and while I have the carb off I was going to pull it apart and clean up the bowls and metering blocks. Thanks for the input though. Anything is greatly appreciated.

 

[cdummer43]

Time for some basic diagnostics. We need air/fuel, compression/timing. Using a timing light , start the engine and let it idle. Is it smooth ?What does the timing mark do ? Steady or moving back and forth? Now raise the rpms and hold it at about 2500 rpms, what does the timing mark do now ? Still smooth ? by the way how are the water temp and oil pressure doing ? Every thing still smooth and perfect ? Or has any thing popped up yet ?

Sorry I recently bought a new house and am getting things all in order for the Mrs. When I get around to grabbing a timing light from my dads house I will get back to you.

I did drive it the other day in hoping the problem would work it's self out(never the case) and it ran well when it was warm out. Went to get in it to go home later in the night and from third gear up to five it would back fire on the initial acceleration after releasing the clutch. My thoughts are its timing, but could easily be the fuel department as well.

 

[moper]

Is the MSD wired directly to the battery? If not check the voltage to the big hot lead and the smaller keyed hot lead to the MSD. Also check grounding of the box.
What do the pins of the connector going to the ignition switch look like? (disconnect and look)