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Re: 318 head porting advice needed
[Re: UltraTwist]
#1569723
01/27/14 10:25 PM
01/27/14 10:25 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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Not sure how far you can go in the bowls just under the seats but I would put in some work there with alot of smoothing/blending. Sharp edges as you know impede flow & also seperate air and fuel molecules away from each other as they are traveling & then they dont combust. back cut the valves & I think on non tulip valves you can smooth out the ski jump transition on the inside of the valve head, might be the other way around that on tulip valves you can
live every 24 hour block of time like it's your last day on earth
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Re: 318 head porting advice needed
[Re: UltraTwist]
#1569724
01/27/14 11:04 PM
01/27/14 11:04 PM
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Joined: May 2003
Posts: 15,487
Florida
scratchnfotraction
I Live Here
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I Live Here
Joined: May 2003
Posts: 15,487
Florida
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Quote:
I'm porting my 318 heads now. I did gasket matching but i don't feel confident about doing the rest because I'm afraid of going too far.
And my question is: Where castings are ussualy thin ? and what spots Should I avoid to not hit water channels ?
find a junk 318 head to practice on first. I went looking for thin spots and water on the junk head. on the other junk head,I paid a machine shop to slice the head up into slices so I could get a sectional look at the casting while I worked on the good heads.
the floor of the exhaust port is kind of a dead spot for flow but side walls and roof are where big gains are found. the air-injection hump in the floor of exhaust port does not change much by removing it so it can stay.
the pushrod pinch area/dogleg in the intake ports are a thin spot to watch for. intake short turn/roof/guide/side walls is where you find big gains.. but you can really kill off flow if not done correctly. I suggest just cleaning up the bowl behind the valve and not mess with the re-shaping the port/guide/bowl on intake side to much unless flow testing them.
if you are going to bigger valves you open up the valve opening to about 80% of valve size and blend the cut line in the bowl. open up the valve opening,then have the seat opened up, then blend the cut line in the pocket,and next to the valve seat.
I use tape on the valve seat in case the tool bumps the seat where it should not..this helps save it from damage.
on my home pocket port with 318 heads,I just up the exhaust valve from 1.50 to a 1.60/I hog the bowl/port out as big as possable and gasket match it to header gasket/flange and then clean up the port/bowl of the intake. then polish the bowl/port to a smooth shine like chrome. dreamel green stone
again,,if you are just doing a home porting/clean up I suggest not re-shaping the guide/port to much unless you are going to flow bench them.
full port jobs I have done by a pro-porter/grinder.
good luck 
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