Camshaft Replacement III: The Search for More Power

LLAP...

I'm getting there.  I was just waiting for this.

This little bugger cost way too much.  But I had to have it, to set up the cam properly.  It is an 'offset key' that shifts the engagement of the camshaft by 2 degrees.

Anyhow, that's done.  I installed the key and rechecked the timing as I described in my last post.  This time, I got (61 + 153) = 214 / 2 = 107.  That's spot on. I'm within a degree and that's good enough for what I can do.

I buttoned up the sump, installed the oil thrower and timing cover and crank pulley, and the bottom end is complete.

And I cleaned, too!

After a short celebratory rest, I turned my attention to the head.  My plan was to polish the combustion chambers, and port and polish the exhaust ports.  I intend to leave the intake ports alone because they already match the diameter of the intake manifold, and I have read that a little 'swirl' (turbulence) is helpful to mix up the intake charge.  Maybe I'm full of it, but that's my story and I'm sticking with it.

Here's the head before I did anything.

Nothing special, right?  Right.

All I did was spend a lot of time with near-infinite patience to gently polish the combustion chamber surfaces to be as smooth as I could get without going mad.  I think I did okay.  I used a small tapered grinding stone and some cylinder and cone-shaped sanding tubes.  I think I got away with it.  I did not appreciably increase the size of the combustion chamber.  Here's a comparison:

And the final result:

Who knows if it will help things.

The real gain I intended to reap was in the exhaust ports.  The port openings are significantly smaller than the manifold's openings as evidenced by the buildup on the manifold gasket.  So I got to work with that tapered grinding stone.  I managed to open things up quite a bit without screwing things up.  After the grinding stone, I used those tapered cylinders up to 240 grit to smooth things out.  Exhaust is one area where you do NOT want swirl; it will slow the exiting gases and you want them to leave quickly. 

Here's a before and after comparison.  The blue marks are where the gasket is larger than the port (and mot matched), and that's what I opened up.

I think that's a lot.  I had to be careful not to break through to the pushrod holes, because that would have been A Bad Thing.

Here's the finished product.

I painted the head after cleaning all the gunk out from the porting process.

All that remains is to assemble the valves to the head and start putting big pieces together!