> I get 15 inches or better at idle. For a long time I had a
>vacuum gauge mounted directly to the intake manifold.
>Good trouble shooting aid.
Yup, your power valve is never opening and your main
jetting is probably rich to compensate.
>I have the closed chambers, Maby if I build up my
>other 351C that is under the bench, I might go to higher
>compression. I previously used 351W heads, open chamber
>and milled a lot, plus pop up pistons to give a true 10.5
>compression on the original Tiger 289. It lived with the
>available gas OK.
With flat tops, closed chamber 4V's and KB pistons (and
probably TRW), you should get around 10.5:1. They move
the pin slightly to bring the piston closer to flush at top
dead center. The Aussie heads are even tighter than
the 4V heads. Mine fall into the 55 to 57 cc range
versus 62 to 64 cc's for the 4V quench heads.
>I liked the grind on the SVO Cam.
It's a pretty good all around grind for 4V heads. The lobe
centers are a bit of a compromise so it can be used for
both open and closed chamber heads (low and high
compression). With quench heads, I'd drop to 110
LSA.
> Did not know they are two piece, My only problem
>with the valves is that I lost an exhaust valve seat probably
>due to the lack of lead in the gas. Need to have that set
>of heads rebuilt with hardened valve seat inserts.
Yup, two piece friction welded together. Plus the keepers
are intentionally loose fit to promote valve rotation. It's
a well known failure mode with stock parts. The fix is to
install stainless steel one piece valves with single groove
keepers. After mine grenaded, I started asking around.
It's happenend to more people than I can count. One of
the locals had it happen twice before he figured it out. One
of the Pantera guys trashed an expensive turbo 351C.
I'm not comfortable with valve seat inserts on cast iron
heads. I've heard several stories of them coming loose.
One of the guys on another list has his own valve grinding
equipment and claims he's never seen a head with recessed
heads that couldn't be traced back to another cause.
I checked the Aussie heads last night. They are like you said
with the webbing removed (compared to 4V heads) at the two
ends. The center is still webbed. All my 4V heads (open, closed,
and aluminum high port A3's) have only small holes in these
areas but the webbing is fairly thin so maybe it's not structural.
Dan Jones
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