There are two "TDC" spots for your crankshaft. Your cam is what determines if it's the "real" top dead center. Easy way to tell is if you pull the #1 plug, and turn the crank, it'll be blowing air out as you head towards TDC with both valves closed. On the other end, it'll have the exhaust AND intake valves open as it's coming to the top, so no air will be trying to come out the plug hole.
Remember, it's a 4-cycle engine - suck, squeeze, bang, blow - so the piston has to reach TCD twice during the combustion cycle. You want the *compression* stroke TDC.
If you can make your engine run at ALL with the firing order verified, then you definitely have it starting from TDC.
My suggestion would be to 1) check your plug order, 2) check your wiring, and 3) I hate HEI distributors SO MUCH. Even when they work right, which they often do.
Ugly Chevy monstrosities.
In all honesty, my only real gripe with them is that they interfere with Monte Carlo bars and air cleaners. If they're the type that has an integral coil built into the cap they're not too great, because they tend to overheat and fail - especially when you're not running a resistor wire to dial your voltage back a bit when the engine's running.
I don't know much about your engine's other hardware, but with your typical cam, you would want between 6-12 degrees of mechanical advance at idle (with vacuum disconnected and plugged so you don't have a vac leak). If you have an original firing-order cam for a 289/302, your timing order is 15426378. If you put in a roller cam, it may well need the HO firing order - which is 13726548.
You should be all in no later than 3000 rpms (2800, usually), with total advance around 32 degrees. A couple degrees higher, if you have good heads with faster burn characteristics.
Hopefully, you have a vacuum can on your HEI, so you can be more conservative on the mechanical idle advance, and still enjoy easy starting and smooth running.
Remember, it's a 4-cycle engine - suck, squeeze, bang, blow - so the piston has to reach TCD twice during the combustion cycle. You want the *compression* stroke TDC.
If you can make your engine run at ALL with the firing order verified, then you definitely have it starting from TDC.
My suggestion would be to 1) check your plug order, 2) check your wiring, and 3) I hate HEI distributors SO MUCH. Even when they work right, which they often do.
In all honesty, my only real gripe with them is that they interfere with Monte Carlo bars and air cleaners. If they're the type that has an integral coil built into the cap they're not too great, because they tend to overheat and fail - especially when you're not running a resistor wire to dial your voltage back a bit when the engine's running.
I don't know much about your engine's other hardware, but with your typical cam, you would want between 6-12 degrees of mechanical advance at idle (with vacuum disconnected and plugged so you don't have a vac leak). If you have an original firing-order cam for a 289/302, your timing order is 15426378. If you put in a roller cam, it may well need the HO firing order - which is 13726548.
You should be all in no later than 3000 rpms (2800, usually), with total advance around 32 degrees. A couple degrees higher, if you have good heads with faster burn characteristics.
Hopefully, you have a vacuum can on your HEI, so you can be more conservative on the mechanical idle advance, and still enjoy easy starting and smooth running.