Header bolts on 350 TBI

[Ralph the german]

Hi guys,

on my 90`350 TBI I wanna change the original cast headers to stainless headers to build a stainless exhaust.
I`m a little bit affraid to loosen the very rusty bolts in the cylinderheads.
Is there any experience that those bolts often break off ? There, I´m not lucky to bolt off the heads to bore old bolts out.
Do I loosen the bolts on cold or hot engine ?

 

[redbird00]

just did this a few weeks ago, i put some wd40 around the bolts as best i could, take it slow to break them loose, i only broke one, twisted the head off, an 8" pipe wrench got it out the rest of the way. good luck.

 

[dhcomp]

Soak with PB blaster as many times as you can first.

Then put a wrench on there (not socket), and tap end with a hammer, lightly, then moderately, a few times in the loosen direction, a few in the tighten direction, repeat a few times. Progressively harder. This seems to free up and jar loose older fasteners. Do this until you feel like you've done it enough, then try to break it loose. You'll break less bolts this way than just trying to undo them straight.

On my 94, i broke 3 bolts just trying to break them loose. On my 91, using the above method, i broke none.

 

[kicker30]

When I took mine off they all came right out, guy I bought the Blazer from said the engine had a rebuild about 20,000 miles before though.

 

[79rustyk10]

Ive never had the exhaust manifold bolts break off while taking them out. However I watched a dude overtighten and break one installing them one time.