Date:         Mon, 20 Nov 2000 14:38:02 -0500
Reply-To:     Robert Donalds <bostneng@FCL-US.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Robert Donalds <bostneng@FCL-US.NET>
Subject:      Half lilley was Boston Bobs AMC rantings
Content-Type: multipart/alternative;

fellow vanagon types an the power hungry

    The testing I have had done showed that I can greatly improve the
air flow threw the heads and
give the engine more torque threw the low end and mid power range. It
appears a majority high lift o gains in air flow came from the extra
valve and custom seat work (much more than just 3 angle valve job). The
testing did show clearly that the stock AMC heads don't flow very well
under .250ths valve lift. I am sure the stock head OEM heads have the
same flow characteristics. the total valve lift of the stock 2.1 intake
valve is .360ths at the retainer that's why the higher ratio rockers are
making a difference they increase the lift to around 450ths.
intake valve flow chart   air flow measured in CFM
stock head on left         ported and hp valve job heads on right
.050 lift        24.8                  33.0
.100 lift        47.1                  55.4
.200 lift       89.6                 103.7
.250 lift       115.4               123.9
.300 lift       125.3               139.5
.350 lift       137.6               156.2
.400 lift       144.9               170.8
.450 lift       147.8               178.2
this is a huge gain in air flow as you can see the stock head at .450ths
lift doesn't flow as well as the reworked head at .350ths lift
I personally don't like the ratio rockers because I think they put more
side load on the already to short intake guides. reworking the heads as
you can see in the chart I have increased flow beyond the ratio rockers
but at lower valve lift with no decrease in reliability
    The cam I have used in my test engine is the same grind as Robert
Lilleys its not a 3/4 grind and is only a tiny bit more duration this
cam would need the properly machined lifters to match the new lobe
profile
  Other developments are that new performance swirl polished valves are
in and bigger valves are also in the works and due in at the end of
December. I plan to continue the next round of flow bench testing when
they arrive
  I have one upgraded engine installed in a syncro with lilley style cam
and above mentioned head work its at my installers shop he tells me its
a big improvement in torque and he says there is less need to down shift
around town he called it the perfect upgrade for a syncro or westy he
also said that the acceleration compares to that of a 2 wheel drive van
with a fresh engine I am offering these upgrades the pricing however is
not yet complete.
updates as they happen
Boston Bob
.


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