This is my first post in here. Any help is greatly appreciated.

I need some help on my 1968 Charger rt 440.

Car specs

440 rebuilt about 10 years ago, but no build sheet. 11:1 compression. Med to large cam (sorry no specs). Adjustable roller rockers on stock heads, Hooker competition header, Holley 800 Dominator (I think) on stock manifold. Orange electronic ignition.

I have 3 problems. I will try and describe the problems and the things I have done to try and fix the problems. Be easy on me. I like to think I am mechanically inclined but its been 20 year since I took auto mechanics in high school.

These problems might all be related but not sure.

Problem 1
After idol the engine will stumble/bog or back fire through the carb. This happens bad when I stab the throttle really fast. Normally driving there is just a little hesitation.

Things done to try and remedy problem 1
Installed larger more aggressive accelerator pump cam. This helped but still had the problem. I then advanced the timing about 5 degrees to about 10-11. This helped dramatically and really woke the car up. But still have a hesitation and will still back fire through the carb with fast throttle input.

Problem 2
This problem happened before and after the changes I did with the first problem. When its over 85 degrees out side or the car is sitting in traffic or at a stop light for a while I will get a pinging at around 2200-2700 rpm at mid throttle. This happens from a stop or while already moving under load. At WOT no ping and if driven like a grandpa and keep it below 2000 RPM no ping. If its cool our side no problem.

Thing done to try and remedy problem 2
I have been using octane booster the stuff with MMT in it. This has helped but the pinging is still there. I tried lowing the timing but that causes problem one to come back worse and it still pings. I disconnected the vacuum advance and it help a little but is more sluggish and will still ping when hot. Is this just a symptom of to high compression with low octane or something that can be tuned out? I have not messed with anything in the carb just the pump cam.

Problem 3
While timing I noticed that the timing marker is bouncing around about 5 degrees advanced. In other words If I'm at 10 it will bounce out to 15. I am timing with the vacuum advance off and plugged.

I have done nothing to try and remedy this. Not sure what to do??

These are my thought now and questions. Do I need to speed up my initial timing and slow down my total timing? If so how? I'm not sure how to install a timing tape. Also how or what springs/bussing or weights do I change in the distributor? Would this fix both problem 1 and 2.

I love my car and it seams no on know how to work on them anymore. Any help would be great!!!

 

It needs about 15 BTDC depends on cam 11/1 is a bit much for pump gas. Try some race gas & see how it runs
You need to replace the dist to get an adjustable one

 

We'll be easy on ya, usually it's terribly harsh here, no not really. Ok let's get to it.

If you have a true 11 to 1 engine with iron heads ignition timing accuracy will be critical. First the 5 degrees jumping at idle could be a sloppy distributor, I would remove it and thoroughly inspect it and see what advance slot mechanism you have. While it is out I would get an accurate TDC mark on the damper with the proper tool. Your total advance, and at what rpm is THE most important item in this discussion, good to check before distributor removal. At this point it will be the time to decide if modification and/or repair to your existing distributor is warranted or new fully adjustable should be purchased. TDC and degree marking up to 40, or tape will be essential.

The carb problem will come later. Don't over look the pump shooter size, if your bog is sustained or long a smaller one will eventually push the same amount of fuel out over a longer period of time. A bigger one will push it out quicker in a large amount which sounds like is what may be needed here.

While your doing all this and before disassembly a hot compression test would be a very good idea. Sorry no easy answer here but some proper tuning before you burn a piston is needed, for sure.

 

If you have a good size cam the problem that happens around 2200-2700 is the vacuum advance is not working correct. A vacuum advance dist. does not work correct with a big cam because you loose vacuum. The total timing starts kicking in around 2000 rpms and above. The spark knock could becoming from the timing not getting advanced correctly at higher rpms when needed.. I run a mechanical advance dist. with any car with a decent size cam. That's why all your Mallory dual points and MSD dist. are mechanical advance not vacuum. A real performance dist. is mechanical advance not vacuum.

Something to think about

 

What adjustable mechanical distributor would your recommend?