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What exactly is pocket porting?

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Old Nov 21, 2005 | 02:59 PM
  #1  
FrankenT/A's Avatar
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From: Chandler
Car: Trans Am
Engine: 350 TPI
What exactly is pocket porting?

First off I have 081 heads on my 350. Most likely the last owner threw in a 350 block and kept all the 305 components on it. So I have close to little money but I have a dremel/rotary tool. Can I use that to pocket port?

Now what is pocket proting? I know it's not a full P&P, but it's done at home I know that. I did a search and only 2 posts came up, 1 for a V6 guy and another for aftermarket heads. Both said that Pocket Porting stock heads is worthless, but one guy with an Lb9 said he is 4mph faster than other guys with his mods because of his pocket ported stock heads.

Now what is the deal? I only ask because it sounds like a D.I.Y at home mod and while I have the TPI off for DIY porting, I might as well try and see if I can POCKET PORT the heads at only the cost of gaskets and dremel bits.

Thanks.
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Old Nov 21, 2005 | 03:52 PM
  #2  
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From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
It is cleanup (porting) of the pockets below the valves. Also called the valve bowls, and therefore also called "bowl work".

You remove casting flash and smooth out the area beneath the valves (with the valves removed from the head). The factory machining leaves rough casting and steps where the tool stops. Cleaning this up makes a significant difference in flow capability.

There is a tech article linked from the thirdgen.org homepage that has pictures of full do-it-yourself home porting. The pocket porting is the same thing without the gasket matching and polishing.

A Dremel isn't an ideal tool for the job. A die grinder with a 1/4" collet is typically preferred.
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Old Nov 22, 2005 | 10:34 AM
  #3  
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
you really have nothing to lose, just don't nick the valve seat.

a dremel will just take a lot longer, but pocket porting isn't a lot of material removal, so it shouldn't be the end of the world.

ideally, get a 1/4" die grinder, electric, and make up a speed controller. Then do a full port job. Most of the power gain is from the pocket porting though, so I wouldn't be too keen on doing a full one anyway. (then again, do you really want to pull the heads again later to redo it?)

make sure you look at sitting bulls thread, and a lot of the threads that fbird88 posted in.
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Old Nov 23, 2005 | 05:26 PM
  #4  
five7kid's Avatar
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From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Re: What exactly is pocket porting?

Originally posted by FrankenT/A
... it's done at home I know that.
It can be done at home, but there are shops that will do it for you as well.
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Old Nov 23, 2005 | 07:59 PM
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Most shops will just plunge a shell mill into the valve bowl, cutting about 1/4" larger than the original bowl. That's ususally enough to enlarge the bowl right to the edge of the valve seat/insert.

This is an example of the difference in he intake valve bowl:



You can do the same by hand, given the time.
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