I have a friend who is having problems with exhaust manifolds bolts coming loose and blowing out gaskets after 100 miles or less ! He is using bolts that are about 1 1/4 inch long with no spring/lock washer just a factory type HD flat washer. He was also advised to only torque to 20ftlb by gasket manufacturer.
I've suggested a longer bolt, a spring/lock washer and torque to 30-35ftlb. Don't really want to go down the loctite route. will spring washers lose their tension? Did all early cars run spring washers on exhaust from factory?
Any tips advice to get these gaskets to stay in place, being a 426 in a tight engine compartment it is a real bear to change them out.......
Posted 2017-09-05 10:25 PM (#547813 - in reply to #547811) Subject: Re: Exhaust manifold bolts coming loose
Expert 5K+
Posts: 9681
Location: So. Cal
The factory generally used studs. Studs don't loosen up as easily, but I generally do use lock washers with them. They will lose their spring after a while, but they will still be effective once they are rusted on there.
Posted 2017-09-06 4:39 AM (#547821 - in reply to #547811) Subject: RE: Exhaust manifold bolts coming loose
Extreme Veteran
Posts: 594
Location: Melbourne, Australia
Ive forgotton the exact terminology but remember them resembling a castle/ castellated nut (finer slots) .... front of it pinched maybe and held tight by slight interference.... pretty much single use items.