Where did my power go?
I went to the drag strip this weekend. My car ran 11.2s two weeks ago. This weekend it was running high 11.6s to low 11.7s. The only thing I did to the car between trips to the track was change the oil, charge the battery, & adjusted the tranny brake. I'll confess that I pulled a bonehead move and tried to start the car with the carb cap still on. I only did it once. The car runs OK, it's not right. Why did I lose 4.5 tenths? Car info and things I've tried are below. The only other thing, is that 2 weeks ago I was getting a puff of smoke sometimes when lifting off the gas at the end of the quarter (exhaust guides maybe going bad).
Car info:
1983 Cutlass
Chevy 350
Proline Heads
Victor Jr Intake
Holley 750
MSD 6-AL with external 2-step
MSD Blaster 2 coil
2-spd powerglide with tranny brake
Ford 9 inch rear with 513's
30x9x15 slicks
Things I've tried:
reset the valves
adjust the timing
swapped distributors
swapped 750 carbs
replaced 3 spark plugs that looked a wet
verfieid battery voltage.
This week I'm going to try changing all the plugs and putting a new set of plug wires on the car.
Help?!?! What else should I try. Where'd my power go?
Thanks