Head porting

Post date: Feb 9, 2012 4:47:54 AM

As with the intake, it's interesting going after an expensive hunk of aluminum - just in this case it's $1700 worth - with a grinder. Since the 403 has a much larger bore than a 455 (4.351" vs 4.126"!!), I unshrouded the valves. Since edelbrock shaped the combustion chamber a little, they had to make it deeper to keep it at 77cc. That meant there were huge cliffs on the outside of the valves. My initial plan was to do it slow and easy so there'd be no need for a valve job.

Right.

So they're getting the valve seats touched up.

While I was in there, I ground out most of the casting flash, smoothed down the combustion chamber, and smoothed the exhaust port. Otherwise, they're pretty good out of the box. Obviously way better than the stock! Lots of guys will spend a ton of time really tweaking the pockets, but for what I'm doing, it's just fine. There's a pretty significant pinch at the pushrods, also. The casting flash was surprising. One piece sitting next to the valve stem was almost the size of a pea!

All told, that took about 5 hours of time and 20 sanding rolls. The aluminum deburring bits were expensive, but really worthwhile.

Hit up the Picasa collection for more pictures.

Here's a before'n'after.