FlashGTA

I talked to my local porting expert and he recommended that I let him do some combustion chamber work to unshroud the intake valve. Has anyone heard of doing this or done it? Was it worth it? I have always heard not to mess with the intake of the Vortec's. I do plan on having the exhaust ported and that's all.

AJ_92RS

I've read a few books by David Vizard about porting heads, and building SBCs. He recommends that you don't mess with the chamber in the Vortec heads, except maybe cleaning them up. But if you unshroud the intake valve, you can mess up the fantastic swirl characteristics of the head.

You'll have to go to Barnes & Noble to see the results yourself. (That's where I got the book). Even increasing the valves to 2.02/2.05 didn't have a big effect on those heads.

I guess they're really uneffected with anything under .500" lift. That may get you excited and thinking 'well I'm gonna be using a .550" lift cam'. Well you gotta realize that a valve spends roughly twice as much time below max lift than it does at max lift.

About the only thing he recommends is cleaning up the intake and exhaust ports with an emory roll. Like slight pocket porting.

The name of the book is "How to Build Max Performance Chevy Small Blocks On A Budget".

I would scan it for you, but I just got the driver for Windows XP, and I don't feel like screwing with it right now.

AJ

AJ_92RS

I dunno if this pic will work....... let me know if it doesn't.

AJ

http://community.webshots.com/storag...3EpXKWk_ph.jpg

FlashGTA

No the picture didn't work. I did find some information in a Car Craft and they said don't mess with the combustion chamber, nuff said. Thanks for the info!

johnsjj2

Here are some pics of what I did to my Vortecs:

johnsjj2

And another:

johnsjj2

1 more:

FlashGTA

It looks like you did similar work to what the porter was talking about to the intake port. Do you have any dyno figures?

johnsjj2

No I don't. I don't have flow numbers either which I wanted to get, but was impatient. It does run very well, but I don't have any numbers.

Jer82Z28

It looks like you didn't take much from the valve side of the xhaust... is that true?

how much did you remove from the manifold side?

I'm in the process of porting my vortecs also.

johnsjj2

I took all the ridges, and most of the bumps out that I could. The short side radius is real smooth, which is where I spent a lot of time. The exhaust ports, I made a little bigger, and polished them to raise the I/E flow %. The intake runners, I didn't do a lot to. I was real worried about screwing up the flow characteristics, so I stayed away from the middle of the runner.