Author Topic: porting and polishing heads  (Read 1490 times)

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jramey

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porting and polishing heads
« on: July 23, 2011, 01:57:52 PM »
So ive searched the forum and read up on all the threads ive found for p&p heads. Im considering buying a second head to build up and want to p&p it myself, just never done it before. So basicly i wanna know the tools needed and the ins and outs of doing the job to maximize the end results. I do uderstand how its done and what to look for but would rather know any tips and tricks you all may know to help me. And what kinda gains am i looking at after the job is complete. Iv already planned on having a 3angle valve job done on it as well

Offline sharpxmen

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Re: porting and polishing heads
« Reply #1 on: July 23, 2011, 03:37:42 PM »
carbide burrs (cylindrical with domed head and eliptical), sanding drums, mini grinding stones and a pencil rotary tool, and some buffing balls

if you combine this with a cam, roller rockers (and possibly longer valves depending on lift), fuel injectors, higher fuel pressure, throttle body, cold air intake you're looking at about 40HP depending how well it's done.
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
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Offline jfrabat

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Re: porting and polishing heads
« Reply #2 on: July 23, 2011, 03:39:24 PM »
So ive searched the forum and read up on all the threads ive found for p&p heads. Im considering buying a second head to build up and want to p&p it myself, just never done it before. So basicly i wanna know the tools needed and the ins and outs of doing the job to maximize the end results. I do uderstand how its done and what to look for but would rather know any tips and tricks you all may know to help me. And what kinda gains am i looking at after the job is complete. Iv already planned on having a 3angle valve job done on it as well

I am considering getting this done myself, but I plan to increase compression as well...
'94 YJ 2.5L with 4" RE lift, Superwinch EPi9.0, FoMoCo e-Fan, SD30 and SD35 w/ARB-5.13, 165A alt., 33" BFG KM2 on 15" AR wheels, Sony sound system, Pavement Ends Hardtop, Hydroboost

jramey

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Re: porting and polishing heads
« Reply #3 on: July 23, 2011, 05:01:32 PM »
I am considering getting this done myself, but I plan to increase compression as well...

The shop i called said theyd resurface the head for 40 bucks

DJackson1357

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Re: porting and polishing heads
« Reply #4 on: July 27, 2011, 04:54:11 PM »
I just finished mine up last week.  For the tools, I'd recommend an elliptical shaped and tree shaped carbide burrs with the 6" (or somewhere around there) shaft.  Use those for the majority of the cutting.  I only really needed the tree shaped carbide burr when cleaning up the valve guide bosses.  I also used a Standard Abrasives porting kit I've had floating around for a while to clean up the casting and polish the exhaust side.

I'd recommend spending most of your time in the bowl area.  The intersection of the valve seat and bowl is pretty bad, so clean up any mismatch in this area.  After this work on the valve guide bosses.  There is a lot of material to work with but go slow until you determine what shape you want.  Remember the flow direction.  There will be two large "fang" areas from where the guide was machined.  Remove these and blend them into the port.  I tried to get the smallest cross sectional area on the exhaust valve guide boss when looking from the chamber.  For the intake side I tried to shape it so there was minimal cross sectional area when coming in from the port side, basically a wedge type shape.  The short side wasn't terrible, I just cleaned up the sharp edges.  Besides that clean up any casting flash you find with the carbide bits.

Following this clean up the intake ports with 40 grit and 80 grit rolls.  The exhaust side can be polished.  For the chamber you really don't need to polish it, but I went to a 120 grit flap wheel.

For a basic build I wouldn't mess with much beside the bowl.  The ports themselves are a decent size.  For a stock cammed engine like mine I'd rather not increase the port volume. 

HTHs


Offline sharpxmen

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Re: porting and polishing heads
« Reply #5 on: July 27, 2011, 06:59:24 PM »
I just finished mine up last week. 

please tell me you took some pictures in the process, would be nice if you post them in the Member's Projects - sounds like a lot of nice work you done on that head.
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

jramey

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Re: porting and polishing heads
« Reply #6 on: July 28, 2011, 01:50:17 PM »
I agree pics would be sweet

DJackson1357

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Re: porting and polishing heads
« Reply #7 on: August 03, 2011, 05:22:04 PM »
The only pictures I have were taken with my phone and the quality isn't the greatest.  The head is back on the engine now, so I can't do much.  I still have an extra head laying around, maybe I'll do some work on it and take pictures if I can get some free time. 

Also, while you're in there have your machine shop put a 30 degree back cut on the valves.