I've used all the methods mentioned, with good
results.
Be aware that planing the block will 'pop-up' the top
of the piston above the deck. This will require either
machine work to the head (flycutting at the Combustion
Chambers) or the pistons (milling to clear the flat
portion of the CC). And will still probably require
pushrod or rocker pedestal attention.
As for pushrods, the aluminum tubes with steel ends
are very easy to shorten to length. Are these still
available though?
The problem with putting spacers under the rocker
pedestals is that the geometry of the rocker arms will
change with respect to the top of the valve stems.
This area is radiused, such that the tip of the rocker
arm both rotates and slides accross the valve stem
tip. I have used the spacers, and experienced abnormal
wear at the rocker tips and valve stem tips. This may
not be such a problem with stock springs, but if you
fit a higher lift cam, and double springs, both the
amount of motion of the parts, and pressure where they
meet is increased. In a racer which gets very frequent
inspection and maintenance, that may be OK. But for a
street car/daily driver, do you want to be doing
monthly teardowns?
Changing the camshaft and lifters, once the head is
off anyway, is not too bad (yes, you should change the
lifters when you change the cam).
I'd go with the flat top pistons, and only mill the
head if compression is still too low. A 'mild' cam
(Kastner 'B' ?) ought to allow you to keep the stock
springs, pushrods, etc. which eliminates a whole slew
of other changes.
--- "Bowen, Patrick" <pbowen@intellinetics.com> wrote:
>
> Another option to planing the head and having to
> argue with the difference
> in height with the pushrods, is to plane the block.
> The benefit of this is
> you take less off to raise the compression more.
> Since you are removing
> less the actual height difference will be less for
> the pushrods. This has
> been recommended to me many times by spit Racers.
> Another option to combat
> the taller pushrods, is to make shims out of
> aluminum cans or such and put
> them underneath the rocker shaft pedestals --
> important make sure you create
> oil holes in the shims where required!!!
>
> Patrick
> as for the octane/compression issue that is all up
> to you and what you want
> to do.
__________________________________________________
Yahoo! Shopping - Thousands of Stores. Millions of Products.
http://shopping.yahoo.com/
|