I have 1970 455 with holley 850dp, torker intake, msd box, msd coil and non hei distributor. I going to use NGK 5858. How much should I gap spark plugs?

 

.040-.045 would probably work well.

 

Thank you Eric, How if i keep them at .030 what will happen?

 

The advantage with running the MSD system with a hotter coil is that you can open your gaps a bit. I doubt running a narrower gap will effect it much as long as the plug gets hot enough not to attract deposits. If you start running into issues you can always remove and re-gap.