So I have a p72 block with jdm itr internals w/ pr3 b16 head supertech valves & valvetrain and itr cams, just got done assembling the motor and tried to start it and I hear this weird grinding noise when I tried starting it and it hesitated to start and if it started it would not run for longer then a second, and kept backfiring every now and then, so I took out the spark plugs because I thought something wrong was with the block but when I try to start it with the plugs out, it sounded fine no grinding noise. As soon as I put the plugs back in and retard the timing a little bit it would still make the same noise. Anyone have this same problem? Any solutions?

 

Dizzy? Can you tell where the noise is coming from?

 

I would tell you to post a video but continuing to try and start a engine with a grinding noise isn't really a good idea. have you tried turning the engine over slowly by hand and listening for any noises or being able to pinpoint the area or location?