So I picked up used 350, typical rusted bolts on ex manifolds. Already snapped 2 bolts....soaking in PB blaster not much help. Propane torch useless. It "appears" my headers dont use that long lower center bolt, so I plan to just cut off at the surface. .... anyone with experience with this issue? Looks like a lot of drilling out the holes and using bolts and nuts?
You need all the bolt holes. They are threaded. Drill them out carefully & centered., Ez-out, re-tap, or install heli-coils if you have to. No on the bolt & nut idea.
Hmmm, if rust spray, and giant wrench wont budge them, how will a skinny easy out do it? I foresee easy outs being snapped also?
Plan "B". Snap them off if they don't budge, then drill the bolt remains out & re-tap or heli-coil. Heads have to come off to fix threads....
They don't use the long center bolt? Are you sure you have the correct headers? It sounds like you have SB Chevy headers. All Buick headers use the center hole. Also, I just went through this. I used MAPP gas torch to get the head around the bolt cherry red and then tapped it with a hammer. None of the original 91K 50 year old bolts broke.
I broke one. also using MAP and being super cautious. I was able to drill it out and retap in the car due to extreme shenanigans and stubbornness. I made a jig out of 1/8" plate steel that bolted up to the head and made a 5/16" pilot hole which I aligned with the broken bolt. Then I used a right angle drill adapter with a shorty 5/16" drill bit. Sean's idea is better for sure.
The headers are on a 72 Buick motor still in car (bad motor). I just went out to garage and looked again with a mirror, and I'll be damned I cannot find a lower center bolt. Picture attached of the h eaders...
OK, you have the correct headers. Usually, the center bolt is a slot in the header flange so you can lift it on and off with the bolt already started. They may not have tightened it after install. I would definitely put one back in it if it were me. The gasket needs support in that area.