Does anyone on the board have any experience with these heads? I bought a set off the Summit demo rack for a 347 project sometime in the future.
I've only seen them on the bench at my local machine shop. Simply awesome casting and still has more wiggle room for a competent porter to improve on. Probably more than a few cnc programs made for it by now too. Aside from some Kasse P38's(which honestly are a bit on the big side for much below a moderate 347 cid street setup) those would be my first choice for a fairly hot 302-331 compression motor type deal. Anything much bigger cid and/or running big compression and/or much higher rpm would be better to port the 195'same or step up to the 205's bigger cross section. Even the smaller versions should easily make 500 horse on a 400+ cid street motor. Gobs of midrange power too.
On the smaller mtrs everything I`ve read from engine builders to places like Yellow Bullit forum say they are awsome hds.
The port work on these heads is quite nice. They were returned to Summit for the scratches circled with the marker in addition to some high metal on the corner of the deck surfaces that can be cleaned up with a file.
another thing to keep in mind with these heads is the improved PTV clearance you gain as the valves get stood up at lessor angles. This has two major benefits that you should try to capitalize on. Increased valve lift(don't go less than .600").. and the ability to mill large amounts of volume from the chamber to get bigger compression. As usual.. you must balance between the two or the valve reliefs get really deep and it quits liking pump gas. Straight E85 or even a premium/e85 blend is the way to go if you really want to push compression. And don't be afraid of 11:1+ static ratios since the bigger cams bleed cylinder pressure anyways. Which of course as you probably know reduces the running compression at low throttle angles to keep detonation out of the tuning mix. I'd be hunting for around 11.5:1 and give it two tunes. One for the track and another for the street. Have fun with it either way you go.
I'm sure the combination will disappoint. Given the fact that I don't drag race anymore, the parts I have so far aren't earth shaking. I just buy stuff based on opportunity. The Compression ratio will be around 10.1:1 with a 62 CC chamber, a .040 head gasket and a set of KB hyper flat tops at zero deck. I have a Z303 FRP cam that will be mated to 1.7 RR arms. The intake will likely be a another Stealth with a 750 CFM Summit carb. Like my 306, a cost effective combo built out of used and discounted parts. Nothing fancy, just more torque and HP than my 306. I figure 420-430 at the crank with accessories.
