anyone have any experience with these on a 500-512 combo. just curious to performance and components for these heads. im currently looking at a set for my next combo. thanks
Don't get me started... If you plan to run a large roller 0.700+" lift to take advantage of the flow, setting up the spring/rocker package is a pain in the @$$.
If you really want to do those heads right, get longer valves, mill off the rocker stands, and re-locate the rockers for proper geometry. Also might be easier with 1.7:1 ratio rocker arms?
I'm using PAC-1326 valve springs, PAC Ti +0.100" retainers, and milled down spring locators (I think 0.020-0.030" thick) to get 2.00" install height. Using 0.060" lash caps and milled off the rocker stands. Using aluminum max wedge style rocker stand "blocks" milled height to get OK geometry. Using my older T&D 1.6:1 ratio rocker arms.
I think T&D and Jesel now make paired shaft rockers to help fix some of the issues?
Forgot, pushrod clearance is not that big a deal if you have the correct offset rocker arms, and there is room to make the pushrod holes larger. Using an offset cup lifter may help the pushrod angle.
The T&D rockers I have have a 0.650" intake offset. I think the standard port victors have use a smaller offset rocker arm.
I think the Indy offset 0.800"? will work too.
The tilt of the intake pushrod will mean you should order slightly longer intake pushrods than exhaust pushrods.
I'm on my second set of these heads. First set were early production, with mild hand porting, mostly just some cleanup work. These heads had casting porosity issues. The center rocker stands cracked and broke off on both heads, and I was using a smaller can and PAC 1325 springs. This is when I originally went to the max wedge blocks. This was maybe a 625-650 HP engine, only using a 264 @ 0.050" solid roller.
Current set of heads are the Hughes monster CNC ported. The new casting is much better and more material has been added in some places. Learning my lesson with the first set, we did the rocker blocks. Also replaced the heli-coils with 3/4" Time-sert threaded bushings.
Oops, Engine is a 499 stroked 400 block with old 440 source kit that had the 4340 I-Beam rods with ARP-2000 bolts. Zero deck pistons. Compression should be around 12.4:1, and using 3/8" 0.145" wall Smith Brother pushrods.
The new cam, I think 272@0.050 intake, 0.726" lift (comp HXL lobes).
I also changed carbs to a QF 1050 4150 style E-85 carb on an Indy single plane. The carb still seems too small for the engine. I'm guessing this should make 700+ corrected HP? I loose a good 20% due to altitude.
This was supposed to be my street/strip car, so trying not to go too crazy on cam duration.
I have only been to the track once late last year with the new combination and I have some tuning to do on the E-85 setup, but that first time out ET's not much better than old setup (worse 60'), but better MPH, so besides engine tuning, the chassis needs alot of help.