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Original Message
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| Cast iron is relatively easy to drill. |
| By Dave Shoe - 04/30/2002 7:14:44 PM; IP 12.2.11.131 |
Any drill press should handle cast iron without hassle.
Cast iron is much easier to drill than steel, but it's critical that you do NOT let the drill bit overheat and burn the iron, or you'll recombine the carbon flake with the iron, creating iron carbide - impossible to drill through and guaranteed to instantly dull drill bits.
Start with a fresh drill bit and use some coolant (oil or water work with cast iron) to keep the iron wet as you drill. Actually, it's not that critical that the iron stay lubed all the time, but the first time you overheat and create carbides, you'll understand what the problem is.
Be sure to drill no deeper than the factory-drilled lower exhaust holes, or else you'll likely hit water. Use an "end tap" so you can cut "full" threads deeper into the shallow hole than a standard "tapered" tap which you start the hole with. Depending on core shift inside the head, you might hit water anyway, so measure twice and be alert.
CJ sized valves work well in these excellent heads, and it's a worthwhile upgrade.
The Edelbrock Performer 390 is not good for those heads, as it's cast for small-runner heads. I'd look for an RPM, F427, MR/PI, or sidewinder intake. A Blue Thunder might be a bit big for the 390, but it's a great street intake which is perfect for those heads.
I'd also weld-up the exhaust heat crossover in any non-stock FE manifold.
JMO,
Shoe. |
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