LT1 cam sound files

Courtesy of Mike Henkel, aka Mikey 97Z M6 on www.cz28.

All Flow #'s are at 28" H2O on the same flow bench, operated by the same

person. These are also with the STOCK valve sizes on both tests. I have

yet to install 2.00/1.56 Manley RaceFlow valves and 3 angle valve job. As you

can see, they hit port stall at .550 lift after porting. IMO this is perfect for

the cam I am going to be using which has about .544 lift on the intake side.

1) First I painted the intake mating surface of the head with some dark colored

paint. I used a Fel-Pro (#1284 I think) intake gasket and used that as a template

for scribing the inside of the gasket onto the head. I begun by removing the

material to gasket match the intake runner. Be careful when removing

material around the area for the pushrod. I kept constantly feeling this area

to make sure it didn't get too thin. I actually broke through on one, and had

to have it welded at a shop. It only cost me 15.00 dollars though.

2) If you turn the head upside down and look at the port roof of the intake

runners, they are slanted at an angle. I basically ported the intake to make

the roof more flat. Beginning at the port entry, all the way into the bowl area.

I actually cut into the hole for the rocker studs. Don't worry about that, it is

very typical with porting these heads and won't hurt anything. Just make

sure you use a sealant on the stud threads when you re-assemble the heads.

3) The port floor of the intake is very good from the factory and only needs a quick

sand with a cartridge roll. This just gets rid of the factory "as cast" finish.

4) Next I worked in the bowl area. This was the hardest area to work on,

since it is so confined. I removed allot of material from the bowl areas

directly under the valve. DO NOT REMOVE MATERIAL FROM THE

SHORT SIDE RADIUS. This is the area that people mess with, and end

up ruining the heads. The factory short side radius is very good and only

needs to be sanded with a cartridge roll, and blended smooth with the

port walls. I took material away from the valve guide area, mostly at the

bottom of the guide (top if your looking down on it). Just keep in mind

that all the surfaces of the runner need to be smooth with no sharp edges

5) The exhaust needed alot of work in the bowls. I also took off some

material around the valve guide. Again I used a Fel-Pro gasket for "D" port

exhaust. I scribed the inside edge of it just like the intake gasket.

CAUTION: Do not try to match the runner size with the gasket on the

exhaust floor (the flat part). I tried, and cut into a water jacket

I took the port floor down to about 1/4" away from the gasket edge

to be safe from the water jacket on the second attempt. After completing the

port job, I polished the exhaust runners with a crossbuff.

6) For the combustion chambers, I used a sanding cartridge and sanded

the cast finish smooth. Be careful not to remove too much material, or you

will end up reducing your compression ratio. I polished mine, but it is not

necessary if you don't want to. Make sure to use some old valves to stick in

the guides while working the combustion chambers. This will help protect

the valve seats from being nicked by the sanding roll. Avoid hitting the seats

The following is information added by George Marengo,

I read David Vizards How to Build & Modify Chevrolet Small-Block V-8 Cylinder Heads and noticed that Mike's otherwise excellent write-up didn't address how to promote swirl and porting the intake guides in general to aid in flow. Essntially, t

he intake guides and the surrounding boss should be formed to a teardrop shape from the port to the seat area, and the back of the boss should be formed into

a wing trailing edge type of shape. The picture to the right shows what I'm talking

about, since pictures are often far more explanatory than mere words :- )

Here are pics on Jordon Musser's site. There's no writeup, but it does have lots of good pictures of what good head porting should look like, as well as lots of other build up pictures: http://www.velocityracing.com/camaro/winter00rebuild/

Here's Standard Abrasives website. It has generic head porting info, but nothing specific to LT1's: http://www.sa-motorsports.com/diyport.htm