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chrisr32 07-13-2019 09:32 AM

Head porting tools for GX390/Predator420
 
I know there are a lot of tools to port heads, but is there an inexpensive starter kit that could be used to improve flow? I already have die grinders and some small bits just have never ported a head before.

Thanks in advance for your help


This is similar to what I have but mine are from Blue Point (Snap-on) that I bought from many, many years ago...

https://www.mscdirect.com/product/details/00478503

Shepard 07-13-2019 12:05 PM

Re: Head porting tools for GX390/Predator420
 
I would suggest a Dremel and and flexible drive cable so you don't have to deal with the tool weight and air hose. The tool is more controllable. Watch some Youtube and learn how its done.

slonomo 07-13-2019 09:27 PM

Re: Head porting tools for GX390/Predator420
 
I wouldn't use anything that aggressive. I liked my Dremel with abrasives. Those heads are aluminum so you have to keep the speed down or the metal will melt into the abrasive. You can use a wire brush to clean out the sandpaper material. Go slow, take your time, take a little off at a time. You can always take off more, but you can't put it back.

raydhd 07-14-2019 04:44 PM

Re: Head porting tools for GX390/Predator420
 
Quote:

Originally Posted by chrisr32 (Post 1635049)
I know there are a lot of tools to port heads, but is there an inexpensive starter kit that could be used to improve flow? I already have die grinders and some small bits just have never ported a head before.

Thanks in advance for your help


This is similar to what I have but mine are from Blue Point (Snap-on) that I bought from many, many years ago...

https://www.mscdirect.com/product/details/00478503

When I did my 2 heads used carbide cutters such as you have. There is a LOT of material to remove in the valve pockets and valve shrouding.I used old valves to protect the valve seats when doing the !/8" right off the seat.There is also a LOT of material on the pyramid around the valve guide. There a long shanked cutter with the seats taped up worked best.Once the big amounts are removed you can use the fine abrasives to clean up the cutter marks.

raydhd 07-15-2019 10:49 AM

Re: Head porting tools for GX390/Predator420
 
1 Attachment(s)
Pics of my 5 carbide cutters plus the 2 tool steel units I use for head porting.I lag bolt the head to a block of wood that is clamped to a table for the heavy material removal such as the valve pockets.It is also mounted this way when I use the tool steel rotary file for the valve unshrouding.

bjorn773 07-20-2019 09:21 AM

Re: Head porting tools for GX390/Predator420
 
I did a quite a bit of chainsaw porting a couple years ago. The Dremel and flex shaft really was the way to go. Take your time, you can take too much off in a hurry. I would also recommend a file card... the carbide tends to load up. The file card will clean out the bit.

chrisr32 07-20-2019 10:46 PM

Re: Head porting tools for GX390/Predator420
 
I do not have any long burs so I will probably get at least one to reach the hard to hit areas and a long roll sander to take out some of the machining marks from the burs. I do also have a Dremel and will probably try porting a Predator 420 head this winter.

Thanks again for your feedback.

chrisr32 10-12-2019 03:23 PM

Re: Head porting tools for GX390/Predator420
 
As an update, I watched a LOT of videos and took the plunge on mildly porting my VC460 head as well as installed roller 1.3:1 roller rockers. Off the line start it launches much harder, ~250 more RPM at WOT and +5 more MPH. I installed a VC timing key at 6 degrees advance prior to this last change and it sometimes kicked back while pull starting it and that hurt. Now it does mot seem to do that so I am contributing this to the 1.3:1 rockers since the valve end gap is the same both with the 1.1:1 and the new roller rockers.

This video of all of them I thought did really good for a high level overview on porting heads.
https://www.youtube.com/watch?v=r99XisKXgAw

BIKERMIKEYBLACK 10-12-2019 05:40 PM

Re: Head porting tools for GX390/Predator420
 
That’s a great video and exactly wat I did on my hemi head It didn’t need much short side radius and blending in is really all u need on a street type engine (golf cart ) some folks get carried away and remove too much which actually hurts performance at lower rpm

Shepard 10-13-2019 12:39 AM

Re: Head porting tools for GX390/Predator420
 
3 Attachment(s)
I was asked about how to port a head. Its hard to explain in words other then knock off all square edges and round them. Again I suggest using a dremel with a flex shaft over a die grinder and 1/4" bits. It's easy to over do things when your cutting as fast as a carbide burr removes metal. Plus you can reach deeper with the shaft handle.
I don't polish the intake port as a certain amount of roughness is helpful in vaporizing the fuel air mix.
I try to make my exhaust port like a horn to the exhaust flange.


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