I've been reading thru all the latest posts to find someone with similar issues but nothing has been close. Thanks in advance for any help with this, I've tried everything I can think of multiple times and I'm about stuck at this point.

I'll start with my setup.

- Everything is brand new except for the block and cylinder heads.

- In a 1970 Mustang, 351 Cleveland bored and stroked to a 408.

- CR should be about 10:1. Compression tested and varies between 180 and 195 across all 8 cylinders.

- Edelbrock dual plane intake under the Atomic EFI.

- MSD 8577 billet distributor with locked out 84211 adjustable rotor phased to 15 degrees retarded (rotated clockwise looking at the top of the rotor, dizzy spins CCW).

- Comp Cams 283THR7 hydraulic roller cam with 107 degree lobe separation, duration @ .050" Intake = 227, Exhaust = 241. Timing gears set straight up.

- MSD 6A firing a Pertronix Blaster coil, forgot these aren't new but almost, they were on the old engine and worked perfectly.



I installed the Atomic EFI with latest updates and set it up to control everything. Here are my initial settings:

- Set up engine size and # of cylinders.

- Timing locked out and set to 15 degrees on the balancer with a Snap On timing light.

- Cam type = Street/Strip but I've tried all 3 settings without any noticeable improvement.

- Fuel Pump = PWM, no return. Shows approx. 40 PSI on display.

- Timing Enabled.

- Idle RPM Target set to 950 and Idle Timing is set to 1050.

- No nitrous or boost.

- All other settings are left at the default settings but I've tried adjusting numerous settings with very limited success.

- I've set the IAC numerous times but I can't get it to stabilize. It will go from 0 to 30 or 35 and then back to 0 and the engine runs extremely poor when the IAC kicks in, it's a little better at 0 but still not running anywhere close to what it should be. The exhaust is full of carbon when the IAC is controlling and clears up when the IAC is at 0. I've noticed the IAC as high as 42 when actually driving and this seems wrong to me but I don't know for sure. I've seen other guys that had to replace their IACs so I'm wondering if mine is pooched too???

- I've gone thru two new sets of spark plugs because they are getting extremely carboned up and I suspected spark shorts due to the carbon but the latest set of plugs didn't make any difference.

- When I try to drive the car, it idles very poorly and when the revs increase to about 2000 RPM it starts to cough and hack with some backfiring so it's essentially undriveable.

- This engine is just gulping the fuel down too so something is definitely way off but I don't know where to look any more.



Holy smokes this got long-winded. Sorry for the info overload but I think I've done everything right and I'm going no place fast.