pocket porting stock ls1 heads
12-28-2011, 11:12 PM
#1
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pocket porting stock ls1 heads i have a simple question but it might be drawn out so illl try to make it short
me and a buddy of mine were at his shop and he had a damaged ls1 head that came out his ws6, well we put it on a bench and he was showing me how he used to pocket port heads, using a 3/8 diamond tip bur bit abourt 1 1/2in long he was knocking off the razor sharp edge on the runners and puting a small inner angle on it
these measurments arent exact so bare with me, the head runners measured about .99, the intake .85 and the gasket around 1.25, so he took the bur but to the heads and started opening them up justabout almost to gasket line,
and he was wondering how far in the runners could he port, when he knocked the edges down we noticed a factory mill line in the middle of the runners and it polished right out ,
i guess my question is could he port and polish the runners the entire 1 1/2 of the bit length or is this something that would have to be done by a profesiional machinist, if all the runners were opened up to the fullest and all were similir but not exact would he gain anything, or does it have to be exact and will mess something up
sorry for the confusion he has a completly disassembled ls6 thats going in his car and was wondering if he could do this to the heads before assembly
me and a buddy of mine were at his shop and he had a damaged ls1 head that came out his ws6, well we put it on a bench and he was showing me how he used to pocket port heads, using a 3/8 diamond tip bur bit abourt 1 1/2in long he was knocking off the razor sharp edge on the runners and puting a small inner angle on it
these measurments arent exact so bare with me, the head runners measured about .99, the intake .85 and the gasket around 1.25, so he took the bur but to the heads and started opening them up justabout almost to gasket line,
and he was wondering how far in the runners could he port, when he knocked the edges down we noticed a factory mill line in the middle of the runners and it polished right out ,
i guess my question is could he port and polish the runners the entire 1 1/2 of the bit length or is this something that would have to be done by a profesiional machinist, if all the runners were opened up to the fullest and all were similir but not exact would he gain anything, or does it have to be exact and will mess something up
sorry for the confusion he has a completly disassembled ls6 thats going in his car and was wondering if he could do this to the heads before assembly
12-29-2011, 12:26 PM
#2
If you look in the exhaust runners you will see a dip in the ceiling.....this dip is s water jacket that runs under the valve spring seat and you have to be careful not to take too much out here and break into the water jacket......when I ported my 241's I had an old cut down head section that showed me exactly where all the passages were
12-29-2011, 07:44 PM
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Some time ago I had taken the trouble to chop-saw a junk 317 head and
took photos of the cross-sections. I posted them on LS1Tech. I do not
recall much more about it, keywords etc.
In general I recall about 1/4" of meat before you'd hit water, minimum.
On my home-ported heads I dressed down the valve guides only to the
point of smoothness (some folks hog the pedestal back flush, I dis not).
I pushed down the swirl ramps but did not entirely flatten. There was a
sharp ridge at the back of the valve seats and I was able to smooth this
out using the backside of a ball burr.
Basically just "be the ball", style porting scraping off anything that seems
like it will whistle or tumble the air.
You may be able to turn up the pics. Never have gotten anything like a
quantitative result let alone a before / after.
took photos of the cross-sections. I posted them on LS1Tech. I do not
recall much more about it, keywords etc.
In general I recall about 1/4" of meat before you'd hit water, minimum.
On my home-ported heads I dressed down the valve guides only to the
point of smoothness (some folks hog the pedestal back flush, I dis not).
I pushed down the swirl ramps but did not entirely flatten. There was a
sharp ridge at the back of the valve seats and I was able to smooth this
out using the backside of a ball burr.
Basically just "be the ball", style porting scraping off anything that seems
like it will whistle or tumble the air.
You may be able to turn up the pics. Never have gotten anything like a
quantitative result let alone a before / after.
