Connecting rods

 

Thanks very much, very good info.

 

Good tech all around.

 

I'm gonna have to quit hangin' out over here - ya'll are making me want to pull again!

On the pulling heads, I cut a 1" hole in top between the head bolt and the valve guide on each side of the intake port on the flat 3" tall heads, or I open up the water ports on the 4" tall heads.  I open up the bottom water port that's right under the intake runner.

 

Now I can fill my access holes with a 1" frost plug and start porting the inside of the intake runner.  I cut that nasty corner out of the intake where the charge has to turn a sharp 90 degree corner to go into one valve bowl or the other.  I fill around the outside of the intake runner and that valve bowl area because I'm going to cut through the original casting there.  the further into the valve bowl you can lay the port back and the longer the radius you can roll into the intake runner, the better they will flow.  The port gets verry wide because of this and the volume is to large to keep air speed up.  I drill a hole in the back of the intake, thread it and put a bolt in, this gives the filler something additional to anchor to and I build a wedge shape with a long sweeping radius on each side into the valve bowls.  I can keep the port volume correct with this and the divider helps direct flow as well as prevent robbing on intake overlap for that given runner.

 

I cut the intake runners into a long tear drop shape to blend into the corners.   On one of my own for a verry fast running engine, I just cut the intake runners out and used a large sleve as I needed lots of volume to feed verry large valves.  It all depends on the size and speed of the engine.  But with that corner cut out of the head, it's not supriseing to see some verry healthy flow numbers.  I'm able to keep water in all these heads yet. 

 

I've got one 4" tall head dry I did for my outlaw engine with split ports that are raised in it and it peaked out at 318 CFM on the intakes!  I had to countersink allen headed bolts in the bottom of the intake ports and plug the access hole in the top because the original head bolts go through the new ports. 

 

On the more "stock engines" and a lot of the pulling heads for these, I run a 1.8-1.9" intake valve depending on the engine.  I cut the corner back in the head quite a ways but don't cut through.  Roll the floor into a nice short side radius.  Just a nice 3 angle valve job and nothing to special.  I've tested some various valve angles, etc.  Really in the end there's verry little difference.  Once the corner is removed, then there's a difference.

 

Depending on compression ratio and engine size, most of the cams get ground to about the same duration in the mid 190's @ .050" but the lobe seperation angle gets changed depending on the engine it's for.  With a siamesed port and a flat crank, they won't take much duration.

 

Nothing's impossiable but some things take some time and thought.