Jeff York wrote:
<<This sure looks like a crack in one of my heads. I know its probably
vague to ask for an opinion based on a photo. >>
Yep, that's a crack, but I'll tell you what Steve Bennett told me about
that...."They all do that, after just a few hours." Well, I haven't
found that to be the case.....they don't all do that, but it does
happen, but usually isn't a mode of failure. I figure I've rebuilt over
100 different VW engines, and I haven't seen any failure caused by a crack.
As for best heads, hands down, it's Revmasters. I've flown several
different brands, and some I took one look at and refused to fly with.
See http://www.n56ml.com/n891jf/vw/ for more than you probably want to
see on VW heads. Buy Revmasters.
Unlike all these other heads Revmaster's don't suffer from "receding
seats", where the seats either wear excessively or sink into the
aluminum head, which tightens the valve lash at the rockers enough to
remove the .006" clearance and MORE. And once that happens, your valves
don't seat, they overheat, then they stretch some more, and then they
SUCK....and you have to find a place to land! Joe Horvath says they are
the very best because he uses some super alloy for the seat itself, and
it has a lot more material below the seat to support it. Whatever it
is, they WORK!
I'm serious....I adjust my valves every 25 hours of flying (like GPASC
recommends), and on other heads, I needed to adjust nearly all of the
valves every time, because the valve to rocker clearances had tightened
up since the last adjustment. With Revmasters, I MAY have ONE that I
think might be a teeny bit tight, or maybe even a teeny bit loose, but
quite often I can't find a good reason to adjust ANY of them. Such was
the case on Monday. By the way, I adjust intake valves to .006" and
exhausts to .008", just for good measure, especially given the high
temperatures these things run when wide open like we tend to run them.
I also run "swivel feet" to spread the load on the valve tip, so the
valve tips don't wear at all.
See http://www.n56ml.com/n891jf/vw/ for more excruciating details....
Mark Langford
m...@n56ml.com
http://www.n56ml.com
Huntsville, AL
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