4mill

[groomzybanshee]

Currently have a stock cylinder motor bored 20over. It's currently ported by kt has stock crank with long rods, cpis, coolheaded, vforce3s. It needs top end freshened up. Thinking about putting a 4mill crank in while it's apart. What will I need to do have done to the porting? Will it be worth the gain?

[uman1030]

You'll have to have it ported for a 4mill wich is basically raising the port timing for the increased stroke. There is a spacer plate that can be used but everything ive read says that it isnt optimal and creates more surfaces to seal making leaks more likely. Biggest benefit of a 4 mill seems to be more low end power and greater torque. I'm no expert and I'm sure some one more knowledgeable may chime in to better explain.

[sstaton1983]

If you go 4 mill you may as well go cub while your at it. Depending on how your cylinders are set up you may need new cylinders anyways.

[trickedcarbine]

^that, or there is always the option of sendin it off to K&T to get the port work adjusted and the proper domes cut. While you're at it you might as well have them set your 4mil crank up to.