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Posted by Chriscase on Wednesday, July 22, 2009 at 14:08:42 :
In Reply to: Replacing the head gasket. posted by Robert N on Wednesday, July 22, 2009 at 12:53:54 :
It might be a good idea to de-torque those skinny heads. Loosen each bolt 90°, then re-torque to half the final value? Then come back and remove the bolts for real. This is based on the assumption that you can warp a head by having only one bolt to full torque, either when installing or removing.
I think the warp limit is pretty big on these heads, .010" or better?
Then scrape the carbon off with a putty knife. An extra-heavy one will help on the black and head surfaces, they need to be clean to bare metal, or maybe a bit of patina, but NO sealer or gasket left. Lots of guys use sandpaper, I like a knotted wire wheel in a hand grinder. Gnarly enough to leave marks in aluminum pistons.
I've never thoguth carbon was a big deal, it's going to biuld up again, all engines have it...
On my own engines, I have used a center punch on the head, between those siamesed cylinders, where the gasket is sooo narrow. A row all along the web, every 1/8 to 1/4". That raises a crown around each punch mark, in the hopes that the crown grabs the gasket, keeping it from blowing back and forth until it gives up in fatigue. Idon't whack tooo hard, just enough to raise that crown.
YMMV, Chris
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