Is .o35 the typical gap on these big blocks? Now that I'm on an MSD box with a matching coil & distributer would opening the gap another .005 to .010 worth anything besides possible misfire? I know in the boosted world when playing with my turbo cars im down a .022-.024 to avoid blow out but on an NA motor is a bigger gap better for a larger spark or is that BS?

.035 is what i fond most often but i do remember back in the early 90's right out of high school i had a buddy that had a 3500 silverado with a 454....it had an HEI dist and i distinctly remember it calling for a gap of .045 for that truck.....so id say it just depends. You can get away with a higher gap with a hotter ign system.....and ive even seen some old timer open the gap on some SBC's that ran crappy and it smoothed out the idle...not sure if the bigger gap help a rich condition or what but it did work.

Marketing says bigger gap better.:rolleyes
I say, gap to .035”-.040” and worry about other things.

Bigger gaps just make ignition issues needing parts replacement happen earlier.

Some older hei’s used ,060” gap. Lol.
Better for emmissions back then, but boy did they eat parts. Cap center buttons, modules, etc.

You know my way back fix on all the gm crab cap issues on the ‘96+ vortecs with cap misfires and burn thru ? .035-.040” plug gaps. Fir years i’d watch others fight the cap issue. Lololol. Painful !!!!

As i’ve posted a bunch, reducing plug gap to .035” on the 496’s (even with their individual coil near plug arrangement) will surely reduce ignition wire and coil issues they seem to have. I’ll put money on it.

Point taken .035 Gap it is for me!