I've got the feeling I'm going to end up building a 9,000 RPM motor
that only gets run up to 7,000. Oh well, that's better than trying to
run a 7,000 RPM motor at 9,000.
I'm going to need to replace my tappets anyways. While it's possible
to upgrade them once the motor is in, it's a lot more difficult than
pushrods. I might as well go for good ones at the start, if it makes
any difference. I would guess that light tappets can make a
significant difference in keeping your valves from becoming mechanical
rev limiters. Actually I don't mind mechanical rev limiters so much as
mechanical piston travel limiters.
What is the wisdom of the list regarding tappets? If you reccomend
something other than stock, what are the downsides? For example do the
unobtanium ultralights only last for 3,000 miles before they wear out?
I know that you need to use the right tappets for the head. I
currently have what I believe is the stock head for a '69:
12H28389. I'm seriously considering getting an aluminum head. I can
get a good deal on one, I'm already hemmoraging money, and in Burgess'
book he says that they reduce nasty things like detonation and
preignition. Or at least that is how I read it.
Do people have any experience with this? Able to run higher
compression, more boost, lower octane etc. with aluminum heads than
with cast iron?
Which tappets do the aluminum heads require? The early or the late?
For the moment, I plan on staying with the stock pushrods or rocker
arms, but if you have something to say about that portion of the valve
train, I'm interested as well.
As you probably all know right now, the car is a supercharged '69
MGBGT. I'm targeting 100-120 hp to the ground. I'm planning on
usually shifting at 6,000 RPM occasionally going as high as 7,000. And
the car will see duty as both a daily driver and a track car.
--
Girling is not a verb.
lrc@red4est.com http://www.red4est.com/lrc
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