Fresh build no start. Flooding
 

So as I've put in the title, I am having trouble getting my freshly built engine to start. Here are some specs, 87 TII, half bridge port and a whole lot of other performance mods. Stock ECU with AFM, stock coils and igniters, 750cc primaries, 1200cc secondaries. I have checked/ done the following: Compression on both rotors are good, spark from leading and trailing coils are good, new plugs, timing of the CAS is good, and I've done a fuel pump kill switch as well for clear flooding.
Every time I attempt to start it, it cranks well, I flip the fuel pump on and it immediately floods. I mean it doesn't even try. If I kill the fuel pump, crank until I lose fuel pressure, pull the plugs and clean them, crank it with no plugs so it can spit out the fuel in it, add a little oil through the spark plug holes for lubrication and put everything back together, it will actually try to start. I'm assuming its because it still has some fuel that is still in the rails but not enough to run off of. If I flip the pump on at the moment it sounds like it's starting, it immediately floods again and I have to start all over. This car has been frustrating me for months and I'm getting sick of it.
So at this point my best guess is the oversized injectors are too much? I've read other people running these sizes on stock tunes and having no problems. Is the fresh build, never been started motor exacerbating the issue? Am I missing something else? I'm really good with piston motors, but these two doritos are killing me. Any help or ideas would be greatly appreciated.

I have pretty similar symptoms except mine is an old tired engine. In your case I think it's just getting it running to bed in the seals.

Maybe use starting fluid or brake cleaner in the vacuum lines to get it to start and run long enough, then add fuel with your switch.

Stock ECU & AFM? Your assumption too much fuel is correct. The 750"s are flooding the engine with 36% more fuel than the stock 550's. You have 77% more overall fuel capacity than stock. Even if you where able to get it to run, once the secondaries come on the engine would drown.

I thought about that but I was afraid of detonation.

So do you think it would run correctly if I put some stock size injectors in it? Would it even run after the engine is broken in with those size injectors without a tune?

What do u mean by tune? Stock ecu is not programmable unless it has the Rtek7 2.1. U don't have much choice otherwise
but to run the 4x 550's.

I guess I'll get a set of stock injectors until the engine is broken in and I go stand alone. Thanks for all the help guys.

If you end up needing them I have a set of 87 TII injectors and resistor pack.

So I got stock injectors installed today, pulled the plugs and cleared the remaining fuel, added a little oil and no change. Fuel is still coming out of the exhaust a dripping on the floor. If I try to start it with a little brake cleaner it tries to start, but as soon as I flip the fuel pump on, it instantly floods. I know it's not on the mechanical side, as it will hold fuel pressure for days. I'm starting to think the injectors are constantly on when cranking, rather than pulsing. I'm once again at a loss. Any help would be appreciated.

do you see the tach blipping when cranking? i had similar issue with flooding and discovered it was tired grounds (pretty much everywhere lol), which i determined when i realized the tach wasnt blipping. This told me the ECU wasnt sending proper ground pulses to the injectors. Did the regrounding procedure detailed by aaroncake and it fixed my problem.

The tach is blipping. I did the grounding procedure by aaroncake a few years ago, however the engine's been out since then, so I'll take a look at all the grounds again.

Are the injectors new? Recently cleaned? I had a set of leaking injectors cause a similar issue on a fresh rebuild. Also, isnthe CAS stabbed correctly, have you tried moving it while cranking to see if it helps?

I just installed brand new stock size injectors. And I stabbed the CAS acording to the service manual, then when I tried to start it and it wouldn't, I double checked the CAS and it's dead on. I have thought about moving the CAS as it's sitting center but I haven't had a chance to mess with it since Saturday.

Just an update for those that have the same problem. We got it started last night. Ended up having to advance the CAS a full tooth before it would fire. It ran for about ten minutes before we ran out of gas. I'll leave the CAS in this position until I can run it for the full 40mins of initial break in, then maybe get a little closer to where it should be. I don't know if I'm supposed to advance the timing more because of the porting I have, but it does make sense to me. Anyway, thanks to all those that replied and helped me figure this out.