Heads and Flycutting

[Steven]

I have a set of heads sitting here at the shop that I'm considering throwing on my car. Albeit they are a little large, I don't see how with a custom grind cam, good matching intake, and a good tune, it couldn't pump out some serious power for a stock shortblock car. I've never had to worry about flycutting or PTV mostly because of aftermarket piston solutions in my motors but since I'd prefer to leave this motor alone, I figured I'd give it a shot. The heads in question are a set of victor Jr 210cc 2.05 intake and I believe 1.6 exhaust valved heads, lightly gasket matched. The only way to make them fit is by flycutting, however I don't have much experience with that and was wondering if anyone here does. Equally the same, I'm questioning whether the amount required to cut out of the piston will be so great that I could either weaken the piston greatly, or unbalance the rotating assembly by removing to much material. These heads are fairly large for the bottom end, and I am partially compelled to scrap the idea because of that. However I don't see how they CAN'T make good power, albeit a little high in the rpm band. I'd appreciate the help.

 

[BigTang]

w/ the proper cam and intake you can make plently of power. you'll probably have to step up your gears a little to make it useful.

Lunati and another company lindy(?) rent and sell flycutting tools. You need about .080" clearance on the intake valve and .100" on the exhaust. you can also use a flat cylinder shaped stone in a die grinder to open up the stock valve relief eyebrows(i'm going that route). as long as you don't cut all the way to the edge of the piston and don't go down below the depth of the existing relief's deepest point you will be ok. You can also retard the cam timing a little to help w/ this. A good custom cam company can explain it better. Its not the total lift of the cam that causes PTV contact, its the opening rate of the cam(ramp speed/rate).

 

[94kingcbra]

You are gonna pull the engine right? I wouldn't even think about attempting something like this with it in the car. Every notch that you cut needs to be the exact same and perfect. It is possible to have an interference fit, and still run without problems. You just gotta figure out the numbers, and take lot's of measurments. Whoever is grinding your cam, should probably be on your speed dial. They should be able to tell you how much you need to grind and most likely the best way to do it. Take your time and, measure 3 times, cut once. Good Luck, Justin