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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