Passed Down 72 Charger Need Some Help Diagnosing

[bobsgtx]

Do yourself a favor and do a compression test before going much farther.

 

[davek]

so it ran fine with the Holley sniper,just started to act up? Tell us from day 1 when you got it. Did it run and then you changed parts or it is just how you got it.

 

[Mike Dorn]

The spitting is being caused by the engine firing on the intake stroke and it blowing through the carb. It’s being caused by the timing either through a crossed wire or in the distributor, pull the valve covers like I said earlier and check for possible bent pushrods.

Sounds good, sounds like next step is to pull the valve covers, just did another check of the plug wires to make sure I’m not losing it and they’re run correctly.

 

[Mike Dorn]

so it ran fine with the Holley sniper,just started to act up? Tell us from day 1 when you got it. Did it run and then you changed parts or it is just how you got it.

No problem and thank you again,

Heard it run and drove it approximately 4 months ago on the carburetor, ran smooth with no issues, I know between now and then nothing has been done to the car as it was in storage and it’s from family.

Pulled it out and began having the issue as shown in the video, the plan with the car was to run through it anyway to make sure everything was good. I initially thought the issue was related to old gas/fouled plugs/etc. This led to replacing the tank, lines etc. I also knew I wanted to go EFI with it so installed everything related I would need for that. Now that I am at this stage I can run it off the carb or the EFI. Both exhibit the same exact behavior and knowing that gas it new, plugs are good and it runs the same on carb or EFI leads me to think it’s something timing related? Or a bent pushrod as mentioned. Happy to provide any additional details. Not exactly sure how the issue starts so suddenly but that’s what had happened.

 

[davek]

well I would take off the valve covers and see if all is good. So what Im understanding is the only thing changed is the carb to efi and you get the same result.

 

[Mike Dorn]

well I would take off the valve covers and see if all is good. So what Im understanding is the only thing changed is the carb to efi and you get the same result.

Yes sir, same issue with either fuel system, splits/ backfires every revolution, just to double check before I pull the valve covers is it possible that there’s a timing issue?

 

[davek]

Have you tried to check for TDC on number 1 and see were the rotor is pointing in the cap?

 

[Mike Dorn]

Have you tried to check for TDC on number 1 and see were the rotor is pointing in the cap?

I hadn’t but just did, this looks correct to me but I could absolutely be missing something.

 

[1968rt]

Stuck or bent valve!!

 

[davek]

pop-off the valve covers not a big deal.

 

[Mike Dorn]

pop-off the valve covers not a big deal.

Good call, found this, I’m assuming this is plenty bent to cause an issue? And what’re my next steps? This is the only pushrod that was bent, is there a chance I can put a fresh pushrod in and she’s fine or there’s definitely valve damage?

 

[NoCar2023]

Is that valve binding in its guide?
With the rocker shaft removed, tap on the valve stem to verify.

 

[Moms68]

Broken rocker or bent pushrod. Exhaust is coming out the carb. Pull your valve covers.

 

[Rusty knuckles]

Dumb question but is your distributor hold down bolt tight? I'm in the firing order is wrong or timing is off. Wondering if your distributor hasn't rotated quite a bit if as you say, nothing has been touched.

 

[davek]

Is that valve binding in its guide?
With the rocker shaft removed, tap on the valve stem to verify.

Mike I would do this.

 

[NoCar2023]

There is a lengthy thread on this forum about fuel deposits, sticky valves, and bent pushrods—but I can't find it right now.
Check them all for binding. They will have a different sound and possibly even stay open.

 

[RussT Plymouths]

This is the only pushrod that was bent, is there a chance I can put a fresh pushrod in and she’s fine or there’s definitely valve damage?

How does the bent pushrod compare in length to the others?

Edit: Intake or Exhaust? I'm guessing Exhaust.

 

[pnora]

To tell the truth is the name of this game. Run a compression test or leak down. A valve is being held open. My bets extra or lost part went down the hatch. A car does not run ok one day and now run like this unless someone had the hatch open.

 

[pnora]

Your video hasn't downloaded yet. So, guessing here but 2 possibilities. Distributor 180 out. Easy check, pull it and install 180° and try it. Other is firing order. Small block rotates clockwise. Check that wires are in correct order and clockwise.

A car does not run 180 out. Poop and backfire. This car runs.

 

[diesel_lv]

A car does not run 180 out. Poop and backfire. This car runs.

Original post without video being uploaded yet says nothing about engine running. But correct, won't run 180 out, but will backfire.