Well I was getting ready to fly cut the stock 89 forged pistons to accept my new Anderson grind, it has .544/.568 lift. My old Holley's had bad seals and guides so I sent them back, they have 2.02 x 1.60 valves. Well I have port matched and polished the new heads, and since the old vlaves just kissed the piston with the 509/.509 lift I new I would need to flycut the pistons, so we set up the cutter and went at it doing one piston. We then put clay on the piston, mounted the head on and one set of rockers with 2 solid lifters to check PTV. Well after we set them up and rotated we removed the head and the valve didn't even touch the clay! We thought WTF, so we added more clay and did it again, this time we got it to touch, I have .200 clearance on the exhaust and .180 on the intake. On the last set I had .139 and the vlaves hit. SO we are standing there trying to figure out how I have .200 clearance with this big cam installed then I noticed that the valves in my new replacment heads are recessed .140 from the surface still 61cc, which the other heads were not recessed. I am going to call Holley tomorrow to find out if something changed, I did get the heads a year before they were released so maybe I got a early model the first time that didn't work good and they switched. Well fly cutting wasn't a total loss as I did need the eyebrow a little bigger because of the 2.02's but boy was I surprised, just thought I share.
We went over the numbers a dozen times and it is defintly in these new heads. I am anxious to see what Holley has to say, these are the Avenger series 300-575.
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Check Out My Site 91GT,Holley SysteMAX II Kit-Heads 2.02" x 1.60" port matched to a 1262,Anderson N-61,24#,76mm C&L,Full MAC exhaust 1-5/8" Long tubes,2-1/2" O.R H-Pipe,2 1/2" cat back, No A/C or PS or emissions, 12" K&N Filter,RNH PERFORMANCE Ram Air,Ron Davis Radiator,Full Suspension,S&W 8pt "X" brace,JAZ seats,3:73's,Welds..etc,4:30's and 31 splines coming very soon!