I bought a 75 dodge van, has a 318, overall it runs good, my problem is trying to set the timing. Can't read the mark on the balancer, I marked it so I could see it, i'm on #1 wire. It pings under load, and has a low speed surgeons also. I lowered the timing by ear, then it feels sluggish. I did notice when the vacuum advance is hooked up the engine acts unstable and doesn't increase RPM. This engine is basically stock, just headers, LD4B intake, eddy 600 carb, any thoughts would be appreciated.

Vacuum hose to distributor disconnected while checking timing?

I've done that.

Let me add, I am noticing that the T light starts flashing fast like a strobe. But will act normal also, does it on every cylinder. This is a good T light, works fine on my other car

Have you checked the timing chain for stretch yet?

Check the inside of the distributor cap for arc marks and look at the center of the rotor for burns.

Have you tried advancing or retarding timing a lot? Eventually the mark should be showing up on the damper.

first we gotta find/fix the light hookup that is making it act up cuz we ain't gonna get a true reading till we do, then basic stuff: initial (on ported)/total/what RPM the total maxes out at/vac can holds vacuum. this'll get us started. what idle RPM?. true TDC on dampener/rotor phasing but easy stuff first. always pinged or just started (any changes preceding it doing that? you can eyeball the dist springs (broken or good & 1 heavy/1 light is OE). holler when you can

make sure the vacuum advance hose is hooked up to the correct port on the carb.