<VV> 95 or 110 heads ?

[Brent Covey]

Hi Ed,

> I'm  building a late model motor,just a nice cruiser, hope to put a.c. on
it
> some day. Looking for something I can run regular fuel in, without spark
> knock.

You'll find a low compression engine that runs well on 87 octane regular
fuel is a somewhat spongy performer. Theres not a lot to pick between your
two prospective heads, but things are less complicated using the 95HP heads,
you wont be disturbing the valvetrain geometry for example.

Factory A/C 110HP engines apparently used the thicker base gaskets to lower
compression but ALSO significantly increased the ignition advance setting;
theres a Turbo engine type timing tag riveted on the accesory housing. These
engines were still considered premium fuel engines but the extra ignition
advance was the reason- the extra advance made them more robust at idle and
off the line with the a/c compressor dragging things down. Just knocking the
advance back should turn them into regular fuel engines albeit somewhat
weakish ones.

> It will be using the 891 cam,hei ignition, 3.27 gear and a 4spd.  Which
heads
> would be best for this combo, 110's (which I already have)  with the
> compression lowered ( spacers under the cylinders) or 95 heads ?  I am
> looking to do this
> on the cheap, without extensive machine work, etc.

With the 4 speed bottom end power wont be as important as with Powerglide,
but do keep in mind the low compression for regular fuels will cost you
around 15% of the engine output, basically about the same effect as carrying
another 400-500 lbs in the car. The extra power and economy from the higher
compression will tend to offset some of the higher fuel costs, if the car is
not ging to see very high annual mileage, you may find the tradeoffs needed
for regular fuel dont save you much and spoil some of the enjoyment of the
car when you are using it.

If you build the engine with 3839891 and low compression, you will have the
option of advancing the timing and switching to premium to recover some
extra output when you are in the mood, at least. Use the stock 110
distibutor centrifugal advance curve, which is a very perfect match for the
891 cam regardless of compression ratio. You will need to experiement a
little with your vacuum advance units to find one that compliments the car
after its together and running.

Good luck,
Brent Covey