Hand finishing CNC heads
Hand finishing CNC heads I have a set of stage one thunderracing CNC heads sitting here and before I put them on what is the best way for me to hand finish the combustion chambers,intake runners,exhaust runners without any disassembly? Can I wet sand them by hand without taking them apart? What can I do now that they are off the car to improve any flow? I have a month to play with them and I would like to polish any where I can by hand without taking them apart. What type of sandpaper should I use? Should they be wet sanded or dry sanded? Is disassembly necessary for hand finishing? Any input appreciated. 
Teching In
Joined: Nov 2002
Posts: 9
Likes: 0
From: VA
If your just hand sand them with sandpaper witout taking them apart, I don't think you are going to do much good. The correct way is to take the valves out and use cartridge rolls and flap wheels on a die grinder to polish the cnc marks out. You also want the valves out to make sure you get all the shavings cleaned out before the heads go on your car. Valve spring compressors aren't very expensive. If you have a die grinder, take them apart. Just be very careful around the valve seat. Make sure to mark your valves to they can go back into the same location. I would also lightly lap the valves back in.
should I just stay away from the area where the valve seats? Maybe lay some tape around the valve seat? What the best way to prevent damaging the valve seat while sanding?
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Originally Posted by 98 Hawk
If your just hand sand them with sandpaper witout taking them apart... You also want the valves out to make sure you get all the shavings cleaned out before the heads go on your car.
I have detailed photos (see the link in my sig or pm me if you want more pics) of what metal shavings will do to the inside of you motor.
Just take your time and "scrub 'em till hell wouldn't have 'em".
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TECH Fanatic
Joined: Sep 2003
Posts: 1,570
Likes: 1
From: San Diego, CA
i doubt you can do anything to increace flow unless the CNC left any old casting marks. And you want to leave the CNC marks on the intake as it helps fuel atomasation
(i know i spelled that wrong)...
if you have a dremel go get some 3M scotch brite bits...(soft ones) they really clean things up! but will not help flow a measurable amount......
post some pics!
(i know i spelled that wrong)...
if you have a dremel go get some 3M scotch brite bits...(soft ones) they really clean things up! but will not help flow a measurable amount......
post some pics!
