Om617a head porting?
Om617a head porting?
12-19-2016, 11:57 AM
#2
The head stands to gain from inside the turn just behind the valves. don't cut too much or you're into the water jacket.
Don't go too crazy on the outside of the head unless you plan on hogging out your manifolds to match.
Budget a couple hundred and get new valve stems pressed in and the valves ground while it's out-that made a huge difference in smoothness.
As for the manifolds, the stock turbo manifold is poorly cast-there are big lumps inside that you can easily remove. Once it's apart it will be obvious.
Polishing is a waste of time, just finish it off with ~200 grit and she's good to go.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
12-19-2016, 11:57 AM #2I ported my head and stock manifolds, the engine ran fine on a stand but it's still yet to go into a car.
The head stands to gain from inside the turn just behind the valves. don't cut too much or you're into the water jacket.
Don't go too crazy on the outside of the head unless you plan on hogging out your manifolds to match.
Budget a couple hundred and get new valve stems pressed in and the valves ground while it's out-that made a huge difference in smoothness.
As for the manifolds, the stock turbo manifold is poorly cast-there are big lumps inside that you can easily remove. Once it's apart it will be obvious.
Polishing is a waste of time, just finish it off with ~200 grit and she's good to go.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
12-20-2016, 06:14 AM
#3
(12-19-2016, 11:57 AM)Simpler=Better I ported my head and stock manifolds, the engine ran fine on a stand but it's still yet to go into a car.Thank you for ththe reply.
The head stands to gain from inside the turn just behind the valves. don't cut too much or you're into the water jacket.
Don't go too crazy on the outside of the head unless you plan on hogging out your manifolds to match.
Budget a couple hundred and get new valve stems pressed in and the valves ground while it's out-that made a huge difference in smoothness.
As for the manifolds, the stock turbo manifold is poorly cast-there are big lumps inside that you can easily remove. Once it's apart it will be obvious.
Polishing is a waste of time, just finish it off with ~200 grit and she's good to go.
(12-19-2016, 11:57 AM)Simpler=Better I ported my head and stock manifolds, the engine ran fine on a stand but it's still yet to go into a car.Thank you for ththe reply.
The head stands to gain from inside the turn just behind the valves. don't cut too much or you're into the water jacket.
Don't go too crazy on the outside of the head unless you plan on hogging out your manifolds to match.
Budget a couple hundred and get new valve stems pressed in and the valves ground while it's out-that made a huge difference in smoothness.
As for the manifolds, the stock turbo manifold is poorly cast-there are big lumps inside that you can easily remove. Once it's apart it will be obvious.
Polishing is a waste of time, just finish it off with ~200 grit and she's good to go.
12-22-2016, 12:24 AM
#4
head is surfaced subtract this from stock amount.Best is valve head flush or nearest to head surface.
Second,mod head in valve area. Taper back the head material just out side the valve,remove more at center of cyl. head tapering to less nearest to next cyl,.
Do the same on the head nearest pre chamber,but cut less,not as much fuel burn on that side. Do not need to remove much.
This is on a article on the forum,diesel performance head mods.do not remember where. Surprised this is not used more often
Works very well,the article states 20-25 h.p. or more. Yes I did this,better performance plus 3-5 m.p.g.better.
Install new seats. Valves usually seat to low in head,seriously shrouding air flow. Max. valve protrusion out of head is .007 thousands,stock head. what ever amount
head is surfaced subtract this from stock amount.Best is valve head flush or nearest to head surface.
Second,mod head in valve area. Taper back the head material just out side the valve,remove more at center of cyl. head tapering to less nearest to next cyl,.
Do the same on the head nearest pre chamber,but cut less,not as much fuel burn on that side. Do not need to remove much.
This is on a article on the forum,diesel performance head mods.do not remember where. Surprised this is not used more often
Works very well,the article states 20-25 h.p. or more. Yes I did this,better performance plus 3-5 m.p.g.better.
12-23-2016, 01:01 PM
#5
(12-22-2016, 12:24 AM)Hercules ... Taper back the head material just out side the valve,remove more at center of cyl. head tapering to less nearest to next cyl,.
Do the same on the head nearest pre chamber,but cut less,not as much fuel burn on that side. Do not need to remove much.
This is on a article on the forum,diesel performance head mods.do not remember where. Surprised this is not used more often
Works very well,the article states 20-25 h.p. or more. Yes I did this,better performance plus 3-5 m.p.g.better.
Are you talking about grinding in the combustion chamber area? What about compression, cold starting, etc.?
Is this the article you were talking about? (see links on Deliveryvalve's post #4)
This post was last modified: 12-23-2016, 01:21 PM by kestreltom.
kestreltom
12-23-2016, 01:01 PM #5(12-22-2016, 12:24 AM)Hercules ... Taper back the head material just out side the valve,remove more at center of cyl. head tapering to less nearest to next cyl,.
Do the same on the head nearest pre chamber,but cut less,not as much fuel burn on that side. Do not need to remove much.
This is on a article on the forum,diesel performance head mods.do not remember where. Surprised this is not used more often
Works very well,the article states 20-25 h.p. or more. Yes I did this,better performance plus 3-5 m.p.g.better.
Are you talking about grinding in the combustion chamber area? What about compression, cold starting, etc.?
Is this the article you were talking about? (see links on Deliveryvalve's post #4)
12-23-2016, 08:24 PM
#6
(12-22-2016, 12:24 AM)Hercules Install new seats. Valves usually seat to low in head,seriously shrouding air flow. Max. valve protrusion out of head is .007 thousands,stock head. what ever amountThose are great results! I am a little lost when trying to figure out where the areas you stated are on the head.
head is surfaced subtract this from stock amount.Best is valve head flush or nearest to head surface.
Second,mod head in valve area. Taper back the head material just out side the valve,remove more at center of cyl. head tapering to less nearest to next cyl,.
Do the same on the head nearest pre chamber,but cut less,not as much fuel burn on that side. Do not need to remove much.
This is on a article on the forum,diesel performance head mods.do not remember where. Surprised this is not used more often
Works very well,the article states 20-25 h.p. or more. Yes I did this,better performance plus 3-5 m.p.g.better.
(12-22-2016, 12:24 AM)Hercules Install new seats. Valves usually seat to low in head,seriously shrouding air flow. Max. valve protrusion out of head is .007 thousands,stock head. what ever amountThose are great results! I am a little lost when trying to figure out where the areas you stated are on the head.
head is surfaced subtract this from stock amount.Best is valve head flush or nearest to head surface.
Second,mod head in valve area. Taper back the head material just out side the valve,remove more at center of cyl. head tapering to less nearest to next cyl,.
Do the same on the head nearest pre chamber,but cut less,not as much fuel burn on that side. Do not need to remove much.
This is on a article on the forum,diesel performance head mods.do not remember where. Surprised this is not used more often
Works very well,the article states 20-25 h.p. or more. Yes I did this,better performance plus 3-5 m.p.g.better.
12-24-2016, 03:27 PM
#7
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
12-24-2016, 03:27 PM #7In the ports, remove more on the manifold side than the injection pump side is what he's talking about
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
12-24-2016, 11:34 PM
#8
Took me about 20min. with a drill and grinding bit.Do not need to remove lots . My old 82 300sd has 720 thousand miles ,starts quickly in freezing temps,
28 degrees F. will start before glow light out. Engine is a bit tired but will pull a grade of 6-8% in top gear,85 plus temps.7500 ft.above sea level
and still have a little left,long hill,6-7 miles upgrade,70 m.p.h. High desert so a bit dry also.
This mod. was done at about 640 thousand miles,down and dirty. Head gasket let go,pull head,clean-up,ck surfaces do mod.reinstall.
Would have been a great time to do a good valve job. No time!!!! So did not do any porting of intakes,did not install new valves and seats.
Valves were seating low in head, Most are Factory to you,but I did unshroud them a small amount, what a differance,glad I did.
Yes Kestreltom that is the article on head mods. Unshroud the valves,combustion chamber mods. Do not worry about compression loss.
Took me about 20min. with a drill and grinding bit.Do not need to remove lots . My old 82 300sd has 720 thousand miles ,starts quickly in freezing temps,
28 degrees F. will start before glow light out. Engine is a bit tired but will pull a grade of 6-8% in top gear,85 plus temps.7500 ft.above sea level
and still have a little left,long hill,6-7 miles upgrade,70 m.p.h. High desert so a bit dry also.
This mod. was done at about 640 thousand miles,down and dirty. Head gasket let go,pull head,clean-up,ck surfaces do mod.reinstall.
Would have been a great time to do a good valve job. No time!!!! So did not do any porting of intakes,did not install new valves and seats.
Valves were seating low in head, Most are Factory to you,but I did unshroud them a small amount, what a differance,glad I did.
12-24-2016, 11:47 PM
#9
(12-24-2016, 11:34 PM)Hercules Yes Kestreltom that is the article on head mods. Unshroud the valves,combustion chamber mods. Do not worry about compression loss.Can you explain unshrouding the valves? is this done on the combustion chamber sides? wouldn't happen to have pictures?
Took me about 20min. with a drill and grinding bit.Do not need to remove lots . My old 82 300sd has 720 thousand miles ,starts quickly in freezing temps,
28 degrees F. will start before glow light out. Engine is a bit tired but will pull a grade of 6-8% in top gear,85 plus temps.7500 ft.above sea level
and still have a little left,long hill,6-7 miles upgrade,70 m.p.h. High desert so a bit dry also.
This mod. was done at about 640 thousand miles,down and dirty. Head gasket let go,pull head,clean-up,ck surfaces do mod.reinstall.
Would have been a great time to do a good valve job. No time!!!! So did not do any porting of intakes,did not install new valves and seats.
Valves were seating low in head, Most are Factory to you,but I did unshroud them a small amount, what a differance,glad I did.
(12-24-2016, 11:34 PM)Hercules Yes Kestreltom that is the article on head mods. Unshroud the valves,combustion chamber mods. Do not worry about compression loss.Can you explain unshrouding the valves? is this done on the combustion chamber sides? wouldn't happen to have pictures?
Took me about 20min. with a drill and grinding bit.Do not need to remove lots . My old 82 300sd has 720 thousand miles ,starts quickly in freezing temps,
28 degrees F. will start before glow light out. Engine is a bit tired but will pull a grade of 6-8% in top gear,85 plus temps.7500 ft.above sea level
and still have a little left,long hill,6-7 miles upgrade,70 m.p.h. High desert so a bit dry also.
This mod. was done at about 640 thousand miles,down and dirty. Head gasket let go,pull head,clean-up,ck surfaces do mod.reinstall.
Would have been a great time to do a good valve job. No time!!!! So did not do any porting of intakes,did not install new valves and seats.
Valves were seating low in head, Most are Factory to you,but I did unshroud them a small amount, what a differance,glad I did.
12-25-2016, 06:45 PM
#10
(12-24-2016, 11:47 PM)EvenglassThe valves in these engines seat low,below head surface,the head material just above shrouds the valve and interferes with good air flow.(12-24-2016, 11:34 PM)Hercules Yes Kestreltom that is the article on head mods. Unshroud the valves,combustion chamber mods. Do not worry about compression loss.Can you explain unshrouding the valves? is this done on the combustion chamber sides? wouldn't happen to have pictures?
Took me about 20min. with a drill and grinding bit.Do not need to remove lots . My old 82 300sd has 720 thousand miles ,starts quickly in freezing temps,
28 degrees F. will start before glow light out. Engine is a bit tired but will pull a grade of 6-8% in top gear,85 plus temps.7500 ft.above sea level
and still have a little left,long hill,6-7 miles upgrade,70 m.p.h. High desert so a bit dry also.
This mod. was done at about 640 thousand miles,down and dirty. Head gasket let go,pull head,clean-up,ck surfaces do mod.reinstall.
Would have been a great time to do a good valve job. No time!!!! So did not do any porting of intakes,did not install new valves and seats.
Valves were seating low in head, Most are Factory to you,but I did unshroud them a small amount, what a differance,glad I did.
Kestreltom has given a link to where at on the forum this article appeared. Go there then look up on internet for the main article,good clear
pictures and good read. No need to go this extensive.
(12-24-2016, 11:47 PM)EvenglassThe valves in these engines seat low,below head surface,the head material just above shrouds the valve and interferes with good air flow.(12-24-2016, 11:34 PM)Hercules Yes Kestreltom that is the article on head mods. Unshroud the valves,combustion chamber mods. Do not worry about compression loss.Can you explain unshrouding the valves? is this done on the combustion chamber sides? wouldn't happen to have pictures?
Took me about 20min. with a drill and grinding bit.Do not need to remove lots . My old 82 300sd has 720 thousand miles ,starts quickly in freezing temps,
28 degrees F. will start before glow light out. Engine is a bit tired but will pull a grade of 6-8% in top gear,85 plus temps.7500 ft.above sea level
and still have a little left,long hill,6-7 miles upgrade,70 m.p.h. High desert so a bit dry also.
This mod. was done at about 640 thousand miles,down and dirty. Head gasket let go,pull head,clean-up,ck surfaces do mod.reinstall.
Would have been a great time to do a good valve job. No time!!!! So did not do any porting of intakes,did not install new valves and seats.
Valves were seating low in head, Most are Factory to you,but I did unshroud them a small amount, what a differance,glad I did.
Kestreltom has given a link to where at on the forum this article appeared. Go there then look up on internet for the main article,good clear
pictures and good read. No need to go this extensive.
12-25-2016, 08:57 PM
#11
(12-25-2016, 06:45 PM)HerculesThank you!(12-24-2016, 11:47 PM)EvenglassThe valves in these engines seat low,below head surface,the head material just above shrouds the valve and interferes with good air flow.(12-24-2016, 11:34 PM)Hercules Yes Kestreltom that is the article on head mods. Unshroud the valves,combustion chamber mods. Do not worry about compression loss.Can you explain unshrouding the valves? is this done on the combustion chamber sides? wouldn't happen to have pictures?
Took me about 20min. with a drill and grinding bit.Do not need to remove lots . My old 82 300sd has 720 thousand miles ,starts quickly in freezing temps,
28 degrees F. will start before glow light out. Engine is a bit tired but will pull a grade of 6-8% in top gear,85 plus temps.7500 ft.above sea level
and still have a little left,long hill,6-7 miles upgrade,70 m.p.h. High desert so a bit dry also.
This mod. was done at about 640 thousand miles,down and dirty. Head gasket let go,pull head,clean-up,ck surfaces do mod.reinstall.
Would have been a great time to do a good valve job. No time!!!! So did not do any porting of intakes,did not install new valves and seats.
Valves were seating low in head, Most are Factory to you,but I did unshroud them a small amount, what a differance,glad I did.
Kestreltom has given a link to where at on the forum this article appeared. Go there then look up on internet for the main article,good clear
pictures and good read. No need to go this extensive.
(12-25-2016, 06:45 PM)HerculesThank you!(12-24-2016, 11:47 PM)EvenglassThe valves in these engines seat low,below head surface,the head material just above shrouds the valve and interferes with good air flow.(12-24-2016, 11:34 PM)Hercules Yes Kestreltom that is the article on head mods. Unshroud the valves,combustion chamber mods. Do not worry about compression loss.Can you explain unshrouding the valves? is this done on the combustion chamber sides? wouldn't happen to have pictures?
Took me about 20min. with a drill and grinding bit.Do not need to remove lots . My old 82 300sd has 720 thousand miles ,starts quickly in freezing temps,
28 degrees F. will start before glow light out. Engine is a bit tired but will pull a grade of 6-8% in top gear,85 plus temps.7500 ft.above sea level
and still have a little left,long hill,6-7 miles upgrade,70 m.p.h. High desert so a bit dry also.
This mod. was done at about 640 thousand miles,down and dirty. Head gasket let go,pull head,clean-up,ck surfaces do mod.reinstall.
Would have been a great time to do a good valve job. No time!!!! So did not do any porting of intakes,did not install new valves and seats.
Valves were seating low in head, Most are Factory to you,but I did unshroud them a small amount, what a differance,glad I did.
Kestreltom has given a link to where at on the forum this article appeared. Go there then look up on internet for the main article,good clear
pictures and good read. No need to go this extensive.
12-26-2016, 08:48 AM
#12
(12-25-2016, 06:45 PM)Hercules The valves in these engines seat low,below head surface,the head material just above shrouds the valve and interferes with good air flow.
Kestreltom has given a link to where at on the forum this article appeared. Go there then look up on internet for the main article,good clear
pictures and good read. No need to go this extensive.
Wow... a 25 hp increase. That is very impressive for these old engines. Indeed the 617a needs all the fluid flow improvement it can get, so this makes sense. Glad to hear that the mod does not adversely affect cold start behavior. Thank you Hercules!
kestreltom
12-26-2016, 08:48 AM #12(12-25-2016, 06:45 PM)Hercules The valves in these engines seat low,below head surface,the head material just above shrouds the valve and interferes with good air flow.
Kestreltom has given a link to where at on the forum this article appeared. Go there then look up on internet for the main article,good clear
pictures and good read. No need to go this extensive.
Wow... a 25 hp increase. That is very impressive for these old engines. Indeed the 617a needs all the fluid flow improvement it can get, so this makes sense. Glad to hear that the mod does not adversely affect cold start behavior. Thank you Hercules!
12-26-2016, 09:40 AM
#13
When you really look into the stock turbo exhaust manifold it's crazy small due to casting errors.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
12-26-2016, 09:40 AM #13Oh yeah, the stock head and manifolds flow like crap.
When you really look into the stock turbo exhaust manifold it's crazy small due to casting errors.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
12-26-2016, 01:44 PM
#14
(12-26-2016, 08:48 AM)kestreltomNo need to go wild ,only cut mine back at the widest 3/16" inch. High mileage Engine. The wife was driving the car to work 400 hundred miles away,she(12-25-2016, 06:45 PM)Hercules The valves in these engines seat low,below head surface,the head material just above shrouds the valve and interferes with good air flow.
Kestreltom has given a link to where at on the forum this article appeared. Go there then look up on internet for the main article,good clear
pictures and good read. No need to go this extensive.
Wow... a 25 hp increase. That is very impressive for these old engines. Indeed the 617a needs all the fluid flow improvement it can get, so this makes sense. Glad to hear that the mod does not adversely affect cold start behavior. Thank you Hercules!
called What did you do to the car? It"s not the same car,drives great,have you done any thing to the fuel gauge? Noticeable fuel mileage increase.
This mod. does work,how much can we take take off?????? Good luck
(12-26-2016, 08:48 AM)kestreltomNo need to go wild ,only cut mine back at the widest 3/16" inch. High mileage Engine. The wife was driving the car to work 400 hundred miles away,she(12-25-2016, 06:45 PM)Hercules The valves in these engines seat low,below head surface,the head material just above shrouds the valve and interferes with good air flow.
Kestreltom has given a link to where at on the forum this article appeared. Go there then look up on internet for the main article,good clear
pictures and good read. No need to go this extensive.
Wow... a 25 hp increase. That is very impressive for these old engines. Indeed the 617a needs all the fluid flow improvement it can get, so this makes sense. Glad to hear that the mod does not adversely affect cold start behavior. Thank you Hercules!
called What did you do to the car? It"s not the same car,drives great,have you done any thing to the fuel gauge? Noticeable fuel mileage increase.
This mod. does work,how much can we take take off?????? Good luck
![[Image: JiQhqx.jpg]](http://imageshack.com/a/img921/4976/JiQhqx.jpg)
![[Image: XZVwto.jpg]](http://imageshack.com/a/img924/4393/XZVwto.jpg)
01-26-2017, 02:19 PM
#18
quicker boost.. The head is fairly thick,the area beyond the taper in the runner as it makes the turn could IMO could be opened and rounded
a bit more. I cut a head up just to see. Same can be done on the under side of intake. Remember to leave most of the taper,open some and
round below as the opening turns towards the runner.
Please posts results.
That should give noticeable improvement . The head area just under the exhaust valve,best to have some taper,speeds up air flow,to help with
quicker boost.. The head is fairly thick,the area beyond the taper in the runner as it makes the turn could IMO could be opened and rounded
a bit more. I cut a head up just to see. Same can be done on the under side of intake. Remember to leave most of the taper,open some and
round below as the opening turns towards the runner.
Please posts results.
01-26-2017, 09:25 PM
#19
(01-26-2017, 02:19 PM)Hercules That should give noticeable improvement . The head area just under the exhaust valve,best to have some taper,speeds up air flow,to help withThank you for the response. I did not change the taper just under the exhaust valve, I just smoothed the sharp casting edge on it. I hope this was ok. This is as far as I'm going with porting, just going to smooth with some sanding next. Is gasgasket matching worth the effort? I will keep you posted. This was a very hot debate in the STD Facebook page.
quicker boost.. The head is fairly thick,the area beyond the taper in the runner as it makes the turn could IMO could be opened and rounded
a bit more. I cut a head up just to see. Same can be done on the under side of intake. Remember to leave most of the taper,open some and
round below as the opening turns towards the runner.
Please posts results.
(01-26-2017, 02:19 PM)Hercules That should give noticeable improvement . The head area just under the exhaust valve,best to have some taper,speeds up air flow,to help withThank you for the response. I did not change the taper just under the exhaust valve, I just smoothed the sharp casting edge on it. I hope this was ok. This is as far as I'm going with porting, just going to smooth with some sanding next. Is gasgasket matching worth the effort? I will keep you posted. This was a very hot debate in the STD Facebook page.
quicker boost.. The head is fairly thick,the area beyond the taper in the runner as it makes the turn could IMO could be opened and rounded
a bit more. I cut a head up just to see. Same can be done on the under side of intake. Remember to leave most of the taper,open some and
round below as the opening turns towards the runner.
Please posts results.
01-26-2017, 11:54 PM
#20
disrupting good air flow. The reverse holds true of exhaust manifold,it should be larger than exit of head,for same season,so say racing
experts,and I do agree. If port matched Ok just did not get the extra bit of performance.
How bad can the back pulse get? On the 240d you can feel the pulsing of air at the intake on front of car, at idle,really slows air speed greatly.
Actually the intake manifold should be about 1/16" smaller at exit than head opening,helps slow down back air pulse when valve is closed,
disrupting good air flow. The reverse holds true of exhaust manifold,it should be larger than exit of head,for same season,so say racing
experts,and I do agree. If port matched Ok just did not get the extra bit of performance.
How bad can the back pulse get? On the 240d you can feel the pulsing of air at the intake on front of car, at idle,really slows air speed greatly.
01-27-2017, 12:04 AM
#21
(01-26-2017, 09:25 PM)EvenglassAll is good. The port runners are good on these heads,just the turns,and opening restricted areas.(01-26-2017, 02:19 PM)Hercules That should give noticeable improvement . The head area just under the exhaust valve,best to have some taper,speeds up air flow,to help withThank you for the response. I did not change the taper just under the exhaust valve, I just smoothed the sharp casting edge on it. I hope this was ok. This is as far as I'm going with porting, just going to smooth with some sanding next. Is gasgasket matching worth the effort? I will keep you posted. This was a very hot debate in the STD Facebook page.
quicker boost.. The head is fairly thick,the area beyond the taper in the runner as it makes the turn could IMO could be opened and rounded
a bit more. I cut a head up just to see. Same can be done on the under side of intake. Remember to leave most of the taper,open some and
round below as the opening turns towards the runner.
Please posts results.
(01-26-2017, 09:25 PM)EvenglassAll is good. The port runners are good on these heads,just the turns,and opening restricted areas.(01-26-2017, 02:19 PM)Hercules That should give noticeable improvement . The head area just under the exhaust valve,best to have some taper,speeds up air flow,to help withThank you for the response. I did not change the taper just under the exhaust valve, I just smoothed the sharp casting edge on it. I hope this was ok. This is as far as I'm going with porting, just going to smooth with some sanding next. Is gasgasket matching worth the effort? I will keep you posted. This was a very hot debate in the STD Facebook page.
quicker boost.. The head is fairly thick,the area beyond the taper in the runner as it makes the turn could IMO could be opened and rounded
a bit more. I cut a head up just to see. Same can be done on the under side of intake. Remember to leave most of the taper,open some and
round below as the opening turns towards the runner.
Please posts results.
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