"XTREME"

HEAD PORTING 101

OK class, you're looking at the exhaust ports of a Small Block Oldsmobile #6 head. First photo shows the center exhaust ports in stock form, take note of the flow restricting EGR/AIR bumps which must be removed. Photo 2 shows an end exhaust port after the EGR/AIR bump has been removed. Take note of the "dimple" that now must be removed. It's an indentation which is removed by grinding and blending the ramp around the dimple until the dimople is gone. This takes some work and attention to detail should be applied so when you finsh the ramp it looks like Photo 3 with EGR/AIR bumps and dimples removed. Take note how the ramp has been finshed and how it's been blended into the ports roof with a smooth transitition. This is done by going back and forth, from side to side with an almond shaped carbide bit. A Die Grinder will remove the EGR/Air bumps very fast with a barrel shaped carbide bit or stone but I would recommend using a Dermel Tool with a flex shaft and almond shaped carbide bit to bring down the ramp. Dremel tool is also better for tear dropping valve guides and when reshaping valve pockets. The flex shaft comes in real handy when raising and widening the intake ports or cleaning them up, as it can go all the way in, up and around turns in the ports.

Now you'll want to raise the exhast port .100 as show in photos above to help increase exhaust flow.

Let take a look at the intake ports shall we ?? To improve flow you'll want to remove the bump you'll find in the intake ports and blend the area flat with the rest of the port as shown in the pictures below.

If you want to make "Big" horsepower you'll want to raise the intake ports roof more than 3/8 of an inch to achieve maximum flow. Easy way to do this is to just lay a Mr.Gasket Big Block intake gasket on the head and take a fine tip felt pen and outline the gasket opening and then grind away as shown in the photo's below.

The only intake available for the SB olds that you could raise the intake ports on to match these Big Block sized ports without welding the tops of the runners was the Edelbrock RPM when I high ported these small block heads. Even it could use some aluminum added above the ports as the roof gets pretty thin. I know of two guys running mid 10s with ported RPM intakes but if you want even distribution to each cylinder there is now a new singleplane intake available from Edelbrock that is said, can be opened up to Big Block sized ports.

I was fortune enough to know someone who welded up the sides and tops of the runners on a 25 year old Holley Street Dominator so it could be ported to match the larger big block sized intake ports, this intake has alot of history.

When tear dropping the valve guides and opening up the valve pocket, BE CAREFULL or you will find the water passage as I did in one of my intake valve pockets. My suggestion is to not to go down as deep as I did. Look at your valve pocket and then look at mine, I removed alot of metal creating those tear dropped valve guide and pocket.