i posted a thread w/ pics in the board but im stuck on the part of porting for the area around the valve guide...ive looked at sitting bulls thread but his guides where already ground alot so im still unsure about how to work them over. ive heard to shape them like an airfoil but im not sure in which direction. like lets say im looking in the intake bowl do i shape like an airfoil where the point is facing the intake port or do i just try and cut alot of that off and point it the other direction. if anyone has before and after pics or somethin that would be alot of help. im affraid to touch them w/ out knowing and how much i can safley take off around the opening of the valve guide. or if i can take off the sparp edges around the top hard to explain it like a circle (valve guide opening) inside a circle (shroud of valve guide) the outter circles are where the sharp edges on the top...its very hard to explain and i will try and get some decent pics but please someone offer some help. thanks
John

 

I'm not a head porter....but these guys are

http://www.airflowresearch.com/

Take a look at their little flash movie on their home page, there is a perfect shot of what your bowls should look like when your done. You can also see how they cut down and contoured the valve guide. As you can see in the picture there is a bronze liner in the aluminum head. They just ground it down till it fit with the rest of the guide. It sorta looks like you have some liners installed in some of the pics you posted. If so, thats how you need to modify them.

Good luck

 

well im at work so i cannot watch the video at the moment but i will check it out when i get to the house this evening...but i dont think i have those liners unless they came stock because these heads have never been touched before that i know of or at least thats what the guy said...and it supposedly only had 80 thousand miles on em.

 

holy cow, that's what they mean when people talk about shaping it like an air foil ???????????

That's totally not what I pictured... geez! So they basically took away material from the sides, then left all the material at the far side radius area??
Is this specific to TBI heads perhaps?

 

I wish I could find some pics of what happens to air as it flows around an object. Carol smith has lots of awsome pics in his books, and all of my engineering books have some good shots, but I can't find anything on the net. I'm just looking in the wrong areas I guess.

The purpose of sharp pointed ridge is to gently seperate the air around the valve and then bring it back together gently avoiding a dead air space behind the valve. Have you ever stood behind a big rock in a river? If you have you know the water is about stoped there and there is very little current. In an intake tract this area is basically uselss, so by contouring the guide you gain back this dead area of the port.

Justlearning: it's not a movie, just a flash app that has 2 or 3 pics that scroll through.

 

well heres some pics of what i did today to the exaust valve guide...do u guys think i messed anything up the couple of times i hit the top?? well here they are


there is a little more on the thin side the thin spot is just at the very very top its only that thin for a millimeter or less

 

and heres what they look like stock u can see i did do a little bit but i backed off alot after knicking the top a few times i hope i didnt mess anything up wheres sitting bull or f-bird88 when u need em...lol...

 

does anyone think i messed up bad?? i dont know

 

Nope, your fine. I would take a 1/2" drill bit and deburr the hole by hand when you get done. This will make sure you have a nice clean hole for the valve to go in. The very end of the valve guide doesn't do much any way. The port looks good so far, now repeat 15 more times!

 

im doin my best im gonna get more aggresive now that i know i didnt screw anything up...but in all the examples ive seen it seems that the boss has a sharp peek to it then rolls off on the sides if that makes since...and ive seen some w/ points on both ends and some facing bowls and others facing ports i guess im just gonna make the point w/ the sharp peeked center pointing tword the ports and just try and carve out a little more on the bowl side. thanks for the imput i was kinda worried.
John

 

Justlearning ...this fine detail work is where the Dremel really shines

 

yeah i broke my dremel though it quit working on me a few months ago and all i have is a little cheapo version that has a hard time on very very thin alluminum so i doubt it would work.