Don Terrill’s Speed-Talk

How much can I angle mill a set of 041's and be safe? Customer wants max compression with flat top pistons. Rules don't allow vortec heads even though they would probably be cheaper and run better.

What's your piston to valve clearance now?
If the heads just flow stock numbers then unless you can Mill enough to pick up atleast 3/4 point of compression I don't know that I would waste my time, as you would likley find more power by running a longer, but colder spark plug.

I have done them .100. But you have to plug up the spark plug cooling holes near the edge of the deck.

Racer18 wrote: ↑Tue Feb 13, 2018 7:20 am How much can I angle mill a set of 041's and be safe? Customer wants max compression with flat top pistons. Rules don't allow vortec heads even though they would probably be cheaper and run better.

The only limit I know of is the intake seat, I have cut .125 many times. It's something you have to keep an eye on the job, not all heads will go to an exact number, .100 is an easy safe number. Like ProPower say's you need to plug the spark plug cooling holes. I stop milling when I am into the valve seat. I do cut the last .005 - .010 flat. Pay attention to valve pocket radial, the maximum angle I have ended up with is 21.5*

Thanks, guys! Its for a 2- barrell stock class. Stock cast iron intake too. Figured getting the compression up will help as much as anything. No port work allowed

Thanks, guys! Its for a 2- barrell stock class. Stock cast iron intake too. Figured getting the compression up will help as much as anything. No port work allowed

Racer18 wrote: ↑Wed Feb 14, 2018 5:01 pm Thanks, guys! Its for a 2- barrell stock class. Stock cast iron intake too. Figured getting the compression up will help as much as anything. No port work allowed

No detectable port work allowed?

LOL Yea, the were measuring stroke with a tape measure a couple seasons ago so...

Fwiw, my old pair of 305HO, -601, 53 cc chamber, 1.84"/1.50" valve heads should be looked into here.

My set cc at 53 and 55 cc's and also at 160 cc's intake port size. They have a double-quench shaped chamber not unlike the old -461, "fuelie", head.

pdq67