Front Brakes Locking On After Car Idles.

When this happens both front wheels lock and loosening bleeders releases brakes. I understand about pushrods adjustment, however, why did this problem occur when we did the V8 conversion. We didn't do anything to the braking system until we experienced this problem. That's when we started changing hoses and adjusting the brakes. Master was changed long before problem showed up. We did the loosening of m/c under suggestion of mopar mechanic and even put washers in to move m/c out, but to no avail. It just seems for some reason the brake system is getting heat soaked. Have considered the line insulation you can buy and putting it over the lines to insulate them. Don't worry about misinformation, more theories/suggestions the better.