im running a 350 bored .40 over with flat top pistons ( like everyone) at about 10.2 compression. i have the plugs gapped at .45 but it stumbles in 3rd gear...when the plugs werent gapped properly between .10-.38 from cylinder to cylinder...i had no stumble. with that compression, should i run .35-.40 compression? thanks
the searches didnt help me so far.

 

What kind of ignition? I'm assuming you've got an HEI ignition, .045" is where you should gap your plugs. Your compression isn't high enough to worry about changing plug gap, I'm running 10.5:1 on iron heads and mine are still at .045". I think your stumble is being caused by something else. How's the coil? Might be getting weak.....

 

there is no box. just a mallory distributor and coil. i had no issues whatsoever with 30 runs or so on it...put new plugs in at wrong gap...it rained real hard then it ran crappy. strong as an ox up to 6500 rpms in 1st and 2nd, but 4k in 3rd it fell on its face!!
no stumble in 1st 2 gears.

 

set the gap to .035 and see what happens,mallory stuff leaves a little to be desired

 

thanks..ill give it a shot.