how big on injectors

Yes run 30's...

not enough information.... what kind of heads/ intake/ cam? to be honest you probably need to go back down to 19's 24's are plenty big enough for any naturally aspirated 302 combo. they can support up to 400 hp. so NO you dont need to go bigger.

What's the compression ratio?

I was getting ask how big on injectors for my combo I was thinking the 30lbers were a little to much. I just don't have any power up top. The search button is great.

Injector HP ratings: divide flow rating by.5 and multiply the result by the number of injectors. This uses a 100% duty cycle. These ratings are for naturally aspirated engines.

Example:
19/.5 = 38, 38 x 8 = 304 HP
24/.5 = 48, 48 x 8 = 384 HP
30/.5 = 60, 60 x 8 = 480 HP

The preferred duty cycle is about 85% maximum, so for a safety factor multiply the final figure times .85.

304 HP x .85 = 258 HP
385 HP x .85 = 326 HP
480 HP x .85 = 408 HP

Remember that the above ratings are at 39 PSI. Increasing the pressure will effectively increase the flow rating. Example: a 19 lb injector will flow 24 lbs at 63 PSI, and a 24 lb injector will flow 30 lbs at 63 PSI.

See http://users.erols.com/srweiss/ to get the calculators used in these examples.

Here's the duty cycle explanation. Duty cycle is how much of the time the intake is open the injectors are turned on. The 85% figure means that for 85% of the time the intake valve is open, the injectors are spraying. The idea is that you want some percentage of the duty cycle left over so that you have some room to grow the process.

If you are at 100% and you need more fuel, all you can do is turn up the fuel pressure. That means the whole fuel curve from idle to WOT is affected. Maybe you are already too rich at idle, and turning up the fuel pressure makes it worse. If you had some injector duty cycle left to play with, a custom tune could use that where it is needed. That would not over richen the whole range from idle to WOT.

I doubt the pinging problem is due to the injectors.

Killercanary is running 24 lb injectors on a more aggressive setup than yours (more cubes/better heads/cam) at only 82% duty cycle.

I run 30's on my n/a pump gas 347 and they're near maxed out fwiw.

I don't think the injectors are your problem either.

I would look at timing. I suspect somewhere you are picking up too much timing when you're getting into it. Try backing your base down to 10° and go from there.

Timing +1

Set the base timing at 10 degrees and the Fuel Pressure @ 38-40 psi with the vac line off. Add timing from there, back it off if you get and knock.