bad engine miss?

[74slnt6]

ok so i have been experiencing a bad miss that just started for no particular reason. It happens whenever the engine is under a heavy load, normally around 3700-4200 rpms. if i take off from a dead stop it wont miss in first, it willl have a slight miss in second, and a pretty severe miss in third until it breaks out of that rpm range then its fine. I have brand new plugs, good gas, the wires are only a year old and look brand new, distributor cap looks good, no oil inside. its a 440 with a 750 holley. and the plugs arent fouled out either. any thoughts on what why this is happening ?

 

[dartkory]

this sounds pretty similar to what my 318 was doing, mine was just doing it at a lower RPM. I have a post on here right now asking the same thing. I changed my fuel filter thinking it might have got plugged, it helped quite a bit, but it is still there a little. Tomorrow im gonna change the fuel pump and check the plugs. I'll let you know if I figure it out.

 

[pettybludart]

Run the car in the dark with the hood open,see if there,s any spark jumping from your plug wires?I once had this problem on #5,7 cylinders on a 340.I now use boot covers with no problems.Just a thought..

 

[1968FormulaS340]

Run the car in the dark with the hood open,see if there,s any spark jumping from your plug wires?I once had this problem on #5,7 cylinders on a 340.I now use boot covers with no problems.Just a thought..

Good call, I was about to suggest the same thing.

If you don't find anything there head back to the basics. Parts that "look" good may not be good enough.