Stage IV heads, let's start with this Dec. 1982 Popular Hot Rodding article.
Stage IV heads ported by the engine builder, Bill LaRoy, on a 4.350 bore 440, 3.75 factory forged crankshaft with hard chromed journals. 12.5:1 compression, race fuel, and a Clay Smith cam of 310 degrees advertised duration with .642" net lift @ .018" lash (I still have the cam card). 630 HP @ 7,000 rpm and 593 LB-FT of torque @ 4,500 rpm. Stage IV heads in 1982........not.......to........bad.
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So sometime in 2004-2005 my son, Cody, brings me this magazine article and says, "Hey Pop did this in 1982! Can't we do something like that now?"
"Yes we can son, but we need cylinder heads." And Cody began to destroy cylinder heads.
After months of destruction and flowbench testing he brought me a set of 452 iron heads. "What about these?" And he showed me the flow sheets.
"I believe we can do something with those son." So we built a 451 stroker for his heads. 9.5:1 compression, 91 octane pump gas, Comp Cams XR292R 292/297 advertised duration, .566/.572 net lift, 621 HP @ 6,100 rpm and 588 LB-FT @ 4,600 rpm.
With 452 iron heads?
"Well to tell the truth Dad, I don't see all that difference between the 452 and the Stage IV heads."
But Cody wanted to use better heads on a bigger engine and I could afford Stage V heads. So I bought him three STG V heads. One to destroy during testing and two for the engine.
He destroyed all three. But at that time he had them flowing over 320 cfm, maybe 330.
"Not to worry Dad. I've learned quite a bit and noticed that the Stage V heads aren't all that different from the 906 heads!"
And he made us a pair of 906 heads that flowed 340+ cfm and made 748 horsepower on a pump gas 500" stroker.
The point? Sorry fellas, they don't make Stage IV and V heads anymore because they weren't all that great anyway! You could do the same thing with 452 and 906 heads
if you knew what you were doing.
I've sold a few sets of lesser test heads on eBay, good quality, but nothing super great on air flow, just to make a few bucks and lower the quantity of iron on the shelves around here.
But the really good heads? We didn't get enough work to keep the doors open for those. People would shat themselves when they asked the price. We've always put more heart and soul in what we do than what we've gotten paid for.
And Cody? He's making different heads now-a-days anyway.
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