Can't rev over 4500 rpm

[RJRENTON]

The ballast requirement should be dependent on the fbo box . I do not know what they like. (Instructions?)

The ballast resistor value depends on the COIL's primary resistance....AND....the ECU's ability to switch the coil's primary winding current. Perhaps you can provide some specific values or omponents used to be able to supply some accurate information/suggestions.
BOB RENTON

 

[RemCharger]

If you read the OP question, and my reply, I think it's quite clear. He was asking about the ballast resistor, and has an msd coil.
Do you know the fbo box requirements.

 

[RemCharger]

From the 4 sec flat website, no ballast required, and don't use an msd coil.
There.

 

[ckessel]

Have you owned this car for awhile or is it a recent purchase? Did a previous owner sneak in a rev limiter and not mention it to you?

 

[RJRENTON]

From the 4 sec flat website, no ballast required, and don't use an msd coil.
There.

EXCELLENT INFORMATION. Looks like a great source for ignition system products
BOB RENTON

 

[Michael_]

Have you owned this car for awhile or is it a recent purchase? Did a previous owner sneak in a rev limiter and not mention it to you?

Was going to write this!

Edit:

But could of course be the aftermarket ignition system as well.

 

[Jc cooper]

Iirc , when installing my FBO box it included a jumper wire for the resister and he was insistent on using a particular coil !

 

[Kern Dog]

Nobody has chimed in to ask for more details?
I had this condition and it turned out to be a flat cam. It would idle okay, rev okay but under full throttle, it popped up through the carburetor. The exhaust lobes were heavily worn on two cylinders so the gases were trying to escape through the intake valves.
A compression test may help but removing the valve covers and looking at the movement of the valves would be better.

 

[Jc cooper]

Good point!

 

[rmchrgr]

The FBO boxes have a built-in rev limiter right on the front - maybe check that to see where it's set?

I'm taking a leap here but it sounds like the car runs OK up to a certain point? IMO something like a flat cam seems less likely because a malady like that would show symptoms across the rpm range and run really rough. truly "bad" parts like a coil or ignition box that took a dump would likely do the same. If something does not work at 4,000 rpm why would it work below that?

In lieu of "bad" parts, things like timing just might need to be checked and adjusted. Don't replace parts until you've done basic checks of what you have including wiring. If someone tried to set timing without the vac. advance disconnected it's likely incorrect.

 

[dadsbee]

https://4secondsflat.com/Ignition.html

 

[hunt2elk]

I have used several FBO boxes. Always with no ballast resistor and always with a Pertronix Flame Thrower coil.

 

[dadsbee]

I have used several FBO boxes. Always with no ballast resistor and always with a Pertronix Flame Thrower coil.

.. and I bet you turned that little dial WAY up as well..

 

[hunt2elk]

.. and I bet you turned that little dial WAY up as well..

They run real clean to 6000, that's as far as I go.

 

[19 69 GTX]

Checked timing and its been locked out. It's the same at idle as it is at 3k. 34 degrees at idle and at 3k. Think I may just order Don's kit from FBO it's a good kit with a new Pertonix coil, new box with rev limiter and a curved distributor by Don. Someone asked if mine has has a rev limiter and I had already called previous owner and ask him and he said no.

 

[19 69 GTX]

What is the timing set at?

Timing has been locked out by previous owner it's 34 idle and at same at 3k.

 

[hunt2elk]

Checked timing and its been locked out. It's the same at idle as it is at 3k. 34 degrees at idle and at 3k. Think I may just order Don's kit from FBO it's a good kit with a new Pertonix coil, new box with rev limiter and a curved distributor by Don. Someone asked if mine has has a rev limiter and I had already called previous owner and ask him and he said no.

I would agree with the FBO box and coil, but I wouldn't recommend buying a distributor from him. Tried twice with him and his are garbage. Buy a Firecore and play with the advance and springs yourself. I can guarantee you will do a better job with it in your car than he can guess at.

 

[19 69 GTX]

I would agree with the FBO box and coil, but I wouldn't recommend buying a distributor from him. Tried twice with him and his are garbage. Buy a Firecore and play with the advance and springs yourself. I can guarantee you will do a better job with it in your car than he can guess at.

Ok thanks for the recommendation. I will get the coil and box I pretty sure they are good stuff

 

[Ron H]

Timing has been locked out by previous owner it's 34 idle and at same at 3k.

This doesn't sound right...if I follow...34 degrees at idle...zero change at 3k rpm??

 

[Cojohnso1]

Got a new 69 gtx 440 and when on the throttle it hits hard but I hit 4500 rpm it starts popping and cracking won't go past 4500 rpm. Any idea what could cause this. I swapped ignition boxes and put a fbo one on it same issue. Has a new carb as well. Could something in distributor be the issue or maybe coil. It has a stock distributor and msd coil but coil runs through a ballist. I didn't think you would run the msd coil through ballist it needs full 12 volts.

To make any accurate suggestion? We must have pictures of car? (Ok, just want to see your Plymouth)