Spark plug gaps

[J-440]

 Been looking at past posts regarding this subject and can't find an answer.  Gotta 440 with only 8.5 comp ratio (motor will be blown later), an MSD 6AL with 46,000 volt blaster coil, FAST EFI,  running on 89 octane pump gas.  Missing anything else?  What would my gap be? 

[Fred]

The gap should be 0.35" 

[J-440]

 Wow .35"!!! That's crazy man.  Don't think my gauge goes that high. Naw I hear ya bro.  So lower compression the smaller the gap and vice versa?

[Fred]

We are talking spark plug gap?
The spark plug gap doesn't change.

[J-440]

 Yes the electrode gap...whoops maybe I worded this wrong?  It's different for every motor and all I could find were stock specs.

[Brightyellow69rtse]

if your running an msd you can open the gap. i run .054 gap kinda an obscure number. like 12 years ago when i put in the msd i was trying to decide between .050 or .060 gap and my dad was right there so he said .054, cuse he was born in 54. so thats the gap i run and have since then.

[404NOTFOUND]

I'm getting awesome results with the same ignition and a .50 gap.

[Chryco Psycho]

I run .045 with high output coils .

[J-440]

 Does comp ratio have any effect on the gap?

[Chryco Psycho]

sort of the fuel is harder to light with more compression so a larger gap exposes more spark as long as the coil has enough power to bridge the gap

[J-440]

 You guys running a .045-.060 gap with 10.0 or more compression I get, but I'm only running 8.5 compression, so a .035" gap sounds reasonable for now?

[Highbanked Hauler]

without a killer ignition I have always run 0.35..

[J-440]

 Got a killer ignition.  MSD 6AL with a 42,000 volt Blaster coil...just need a gap spec.  Is there a calculator for determining this?

[Fred]

You guys running a .045-.060 gap with 10.0 or more compression I get, but I'm only running 8.5 compression, so a .035" gap sounds reasonable for now?

Yes it does. .35 is recommended for 8.5 compression.

[A383Wing]

just because you have a 42,000 volt coil, does not mean you are getting all that voltage to the plugs...

if the plugs only require 10,000 volts to jump the electrode gap, that's all it's gonna put out to the plugs

I run .045" with my MSD on a 9.0 to 1 engine

Bryan

[J-440]

 Cool.  Thanks for the help guys. Ya'll always come through.

[ACUDANUT]

I have never "gaped" my plugs.  They all run great as is.

[Chryco Psycho]

even when they get dropped ??

[ACUDANUT]

if they get droped than, you obviously have to make sure the gap is still good.

[A383Wing]