Atilla the Fun

I should note, that if you're doing exhaust guide bosses, with the decks toward you, do all 8 before moving on to something else, or even going in through the exhaust ports. Focus on one thing at a time, and do all 8 in series.

Atilla the Fun

Atilla the Fun

If you think you might ever try 1.6:1 rockers, and your vortecs have these round pushrod holes instead of the slots, then get a 1/2" drill bit, and hand-drill the pushrod holes, using a relatively fast drill speed, and relatively light pressure.
I say there's no good reason to ever try the 1.6 rockers on the intakes unless you have a stock L98 or stock LT1 cam.

Atilla the Fun

Okay, pics this afternoon!

Atilla the Fun

I hope it's understood that up until 11:59 A.M. tomorrow does technically qualify as being after noon today. Something more pressing came up. But it gives you a few more hours to get ready.
It's okay to dull your new carbide burr on a junk practice head. New burrs tend to dig in, jump around, and bend themselves. It's maddening.
I suggest you fing anything iron and disposable to run your new burr against before starting in any ports.
We are going to start in the exhaust ports, the first thing to do is to taper the guide bosses. But wait for me to post a pic of a finished one so you can see what you're trying to accomplish.

Atilla the Fun

Atilla the Fun

Atilla the Fun

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Atilla the Fun

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Atilla the Fun

Okay, I'll make a lot more progress this morning, more pics tonight.

Atilla the Fun

Okay, I have the pics right now, but I need to explain 2 more things first.
One, I'm breaking my own rules, mostly because I've done about 2 dozen sets of these heads, and I'm just trying to best illustrate what's needed. Two, as one of these pics will show, this particular set of heads has suffered seat recession, so they need to be cut for 1.60" exhaust valves, which will be a stage 2. But most of you will be staying with 1.50" and stage one, so I'm going ahead with that, in the port that had the least seat recession.
I know there's someone out there who will just grind away their recession lips and forge ahead, and in the world of Mad Max, that would be serviceable for a little while, but the problem will get worse and worse, faster and faster.

Atilla the Fun

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Atilla the Fun

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Atilla the Fun

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Atilla the Fun

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Atilla the Fun

Atilla the Fun

Here I went ahead with some polishing to again illustrate how the light can make smooth results look rough. Remember, believe your fingertips more than your eyes. Also notice the narrowing of the guide boss. The port walls aren't very thick, to try your best to keep your carbide off them. You can do all the walls need with the 120-grit polishing rolls.

Atilla the Fun

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Atilla the Fun

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Atilla the Fun

both of those pics have plenty of tricks of the light, but notice I don't enlarge the port exit, where it meets the headers. Mostly it's not necessary, you can get over 200 cfm without reshaping it, and second, keeping it small helps against reversion.

Atilla the Fun

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Atilla the Fun

The most difficult, most critical part of Vortec heads: the exhaust short turns. You're trying to create a nice radius. Remove the least iron possible. You can always take more later, you can never put it back.

Atilla the Fun

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Atilla the Fun

Again, polishing can help you find what needs more grinding.

Atilla the Fun

Atilla the Fun

In red, you see I need to let the carbide kiss it again. In green, you see what most guys grind away, but the bench says leave it alone.

InfernalVortex

iTrader: (4)

Thank you for taking the time!

Atilla the Fun

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Atilla the Fun

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Atilla the Fun

Atilla the Fun

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Atilla the Fun

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Atilla the Fun

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Atilla the Fun

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Atilla the Fun

you don't have to 100% remove the bump, what you're trying to accomplish is less turbulence. It can be ground away, but better a bump than a dish.

Atilla the Fun

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Atilla the Fun

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Atilla the Fun

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Atilla the Fun

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Atilla the Fun

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Atilla the Fun

last pic today, because my batteries are dead. Here's the same pic, but less blurry and no green outline.
When I get batteries, I'll get pics of the finished, fully-polished exhaust port.
This is my stage one, I do have old 2004 results for it.
at 0.100" the stock port and stock valve flowed 46. the stage 1 with better valves was up to 50. At 0.200", from 98 up to 109. At 0.300", from 132 up to 140. At 0.400", from 140 up to 159. At 0.500", from 143 up to 167.
Going to stage 2 will further improve that to the following: 0.100" = 57, 0.200" = 114, 0.300" = 149, 0.400" = 167, 0.500" = 177, 0.600" = 181
and remember, these tests did NOT use a length of header tubing, which nearly always improves the numbers.

NemeSS-TyranT

iTrader: (1)

good thread. my old boss was big on circle track racing and built some killer sbc engines with vortecs and iron eagles. he was an old school circle track racer.
its nice to have access to a sf600, i know

ASE doc

Beautiful chamber work. And with a carbide only, no rolls. You have a real talent for port work.

Atilla the Fun

thanks guys. ASE doc, I did use 120-grit rolls in the Dart chambers, haven't gotten that far yet on the Vortecs. But I have a box of new rolls ready for finishing these Vortecs when the time comes.

one92rs

iTrader: (5)

i am going to the tool store this weekend. will get my bit then. also going to pull the heads and try this. kinda scared since i have never done this. but i am going to try like hell to do it. dont want to mess up my 062 vortec heads.

Atilla the Fun

That's part of why I'm having you start on the exhaust guide bosses. That's what needs the most material removed. Rough all 8 of them before getting to the final shaping. Remember, keep the carbide moving. And to do Vortec exhausts, you must use a 3/8" oval burr with 4" overall length. No other shape or size will work, no shorter length will work, longer length must be hack-sawed down.
When doing Vortec exhaust guide bosses, the whole boss gets done through the seat, not any from the header face.
If you've never done anything even remotely like this before, then start by trying to grind away the casting number.
Also, if you're not sure how fast to be running the carbide, less rpm is usually better than full speed. Too fast or too slow will have the burr bouncing and gouging.
Don't use a death grip, but keep absolute control of the tool.
Wearing a breather mask and safety glasses at the same time is challenging. If you're like me, and end up removing one or the other, then when grinding, keep the safety glasses on, and when polishing, keep the breather mask on.
The best thing about porting is that any point is a stopping point. There's never an instance when you can't stop, for whatever reason.
Tomorrow I plan to do the chamber work and the intake port.

one92rs

iTrader: (5)

cool. i am going to start this weekend. heck if i have a question i can pm you or put up a post with pics. this is going to be cool. i love learning.

Atilla the Fun

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InfernalVortex

iTrader: (4)

How big of an impact on power will porting the exhaust side make? I keep hearing that the intake side is hard to really improve.

But I've got 1.60 exh valves in mine, but the ports themselves werent smoothed out and transitioned from the new larger valves... I've been wanting to pull it apart and clean that up for a while, but I just dont feel like getting a new valve job done so I havent bothered yet. I wonder how much power I'm losing because of that.

I need to get it clearanced for more lift anyway though so I can put a serious cam in it.

Atilla the Fun

Vortec intakes can show huge numbers, but not from entry level porting.
the bigger exhaust valves aren't helping you enough to even mention in passing, until you do the 75 degree bowl hog to the maximum depth possible, while not hitting the guide boss, but also while narrowing the 60 degree cut to just over 0.050" wide.
also, you must then blend the 75 into the port, and at this point, the port really responds to tapering the guide boss. From there, do a full polish of all the exhaust ports.
Also, these are the valves you NEED: http://www.competitionproducts.com/S...ductinfo/8435/
and then get a small 30 degree back cut on each and every one of them.
Do all that, you'll be close to my stage 2, which I'll be showing as soon as my funds permit.
By the way, DO NOT go over 0.480" intake lift. COMP has plenty of lobes that'll keep you in the sweet spot.