2.3 Miss

[38racing]

Ford 2.3 motor, stock bottom end, built head, running at about 7200rpm. Motor ran great for about the first 8 laps. Then on the last 4 laps, starting missing when I got into the 6500 & higher rpm range. Lower rpm range motor ran fine. Engine did diesel a bit when I shut it off. Tried checking the timing and everything looks lined up. Put in a new coil and ignition module and still have problem. Pulled spark plugs and they were all "paper sack brown" in color. Anybody have any other ideas?

[84Dave]

If you have the plugs gapped @ ~.040", pull the gap back to .030" and try it. With the engine warm, shut it down and immediately remove the bowl sight-plug on the Holley. The fuel level should be about 1/16" below the threads in the sight-plug. Replace the o-ring on the needle-seat assembly of the Holley. If it's old & worn, fuel pressure can blow fuel by the needle-seat and 'flood' the engine. Fuel pressure 5# or less? 'Run On' @ engine shut-down? Sounds as though the throttle blades have too much of the fuel-transfer slot exposed @ idle. I.E. the blades are to far open @ idle. That can cause major problems when you get out of the throttle into a corner. The high vacuum can pull excessive fuel out of the transfer slot & flood the engine. The engine will 'sag' out of the corner, and as it begins to 'clear' at elevated rpm, and if the AFR is about 10.5:1, you can experience a high rpm 'rich miss'. Particularly if the ignition may be running out of 'reserve' @ higher rpm. Other than the above..... the engine should run fine! -Dave-

[Racedad]

Try Daves tighter gap,but when chasing a missfire always try different plugs one of the first things.


Get that bad boy up for Friday night!