Should I use Exhaust Manifold Bolts or Studs ?

[BuickNut]

I am getting a complete bolt set for my '73 Buick Century GS Stage 1 with a 455 and 4 speed. Should I use exhaust manifold bolts, or use studs ? I pulled the heads on an '88 vehicle with exhaust manifold bolts, and the shanks snapped on 1/3 of them, and I couldn't get them out no matter how much heat, PB Blaster etc. I applied. Getting them out in the vehicle would have been impossible as the heat couldn't get to the affected area. Would studs be a better fastener application here ? I know if I use studs, and I ever have to remove the exhaust manifolds in the future, I'll have to pull the heads as the manifolds wouldn't clear the studs after the nuts were removed - but would that be worth it vs possibly snapping the manifold BOLTS ? Also, on the down side - would the nuts/exposed stud threads rust making the studs/nusts effectively into a bolt anyway over time ??? Drilling and retapping where the bolts might snap is usually a pain because car not to drill into the water jackets.

[DugsSin]

I am going with the ARP stainless bolts and a liberal coating of anti-sieze. Seems I can't leave the motors alone for more than a couple of years and haven't had any problems pulling them apart. My two cents.

[Guest brh]

When I use to work on exhaust systems I hated General Motors because the bolts always snapped. Mopar and Ford were easy because they used a nut and a bolt so all you had to do was snap it off and replace em. I don't know how your manifold is set up so this may not be possible but if I were you I'd drill through the whole thing and be done with it.

[NTX5467]

What needs to be considered is that the bolt is designed to break before it would hurt the threads into which it is screwed. That tends to dictate a somewhat soft material that will also rust easier than a harder bolt would. Yet, when it rusts it should also have enough porosity that a really good penetrant would work.

I concur that a harder Grade 8 bolt or stainless fasteners would tend to lessen the problem, as would anti-seize compound. Only thing is to check to see if the specified bolt/nut torque is rated for lubricated fasteners or for dry threads. The anti-seize compound could provide enough more effective lubrication to make 35 "pounds" of torque equalte to 50 "pounds" with dry threads, for example. Hence, be careful so you don't pull the threads out when you tighten things down.

Typically, a stud is a better fastener than a bolt as the stud will provide a more stable mount and could save the threads as it will stay put as the items attached to it are removed and reinstalled frequently. Plus, a stud can bottom out in the hole whereas a bolt never should bottom out in the hole. There are reasons that studs are used in some places and bolts in others, other than just ease of assembly or item cost.

Just some thoughts . . .

NTX5467