Alright, so. Picked up a '76 280 close to two months ago now. Motor was rebuilt, didn't run for a lot, a LOT of reasons, massive vacuum leaks, incorrect wiring, missing injector o-rings (like wtf?)

Obviously the guy who rebuilt that thing was half handicapped. Luckily I got the car running after fixing these various issues but it's giving me grief relating to ignition timing.

I'll make this very short and condensed as to not bore you guys to death but I have the motor set up top dead center, as seen below:



While on compression stroke, as seen below:



Base timing is set correctly as see below:



Finally distributor rotor is pointing towards cylinder number one, which it should be. As seen below:



Okay, SO. Here is my issue. I have ignition timing set to 10 degrees as it should at approximately 800 rpms. When it's set here, the car will free rev while in neutral just fine, but have minor intake popping. But while I drove it it ran like a bag of ***, would NOT rev past 4000 rpms, just wasn't drivable at all.

So because there were intake pops I decided to advance the timing, it got better. I advanced it as far as I could humanly go and it got going quite well! Car is at 90% currently but still has certain periods of bogging.

So my question is... What's off here? Is the distributor timing shaft off a tooth? Why would I have to run +20 degrees just to get it to run decently. I initially thought it was a fuel pressure issue due to low vacuum which resulted in me replacing nearly EVERYTHING, new fuel injectors, new fuel pump, new filter, new plugs, new wires, new fuel pressure regulator. But while the timing is advanced all the way, vac got better, everything just got better.

What do you guys think? Any help would be KINDLY appreciated. I just wanna drive her in all her beauty. And oh here is what she looks like!

 

I don't see how you can rebuild an engine and not clean or even wipe off the old crud. If your popping out of the intake it means the intake valves are still open when it fires. Cam out of time or bent valve. The top of the piston is showing signs of severe detonation. All the issues you've had are indicating that guy was not a good mechanic at all.
I think you need to pull it and start over. All in all the car looks good with nice wheels except for that gapeing hole in the front.

 

When I advanced the timing the intake popping ceased. I do agree that the guy who rebuilt it was an idiot but I don't think there are any bent valves. When it's not cutting out for that split second under WOT it has excellent power and no smoking of any sort.

The motor is cleaner than it looks, I over exposed all the photos to make them more crisp. /doesn't care how it looks as long as it runs and cam timing is in sync. So looking elsewhere.

 

You need to pull the dizzy completely out and check the position of the drive tang compared to the FSM. One tooth off makes all the difference and you can't see that just looking at the rotor.