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Post by alancase on Aug 9, 2008 22:11:29 GMT -5
Hi, Would anyone have any pics of a flowed head (SR500) they would like to share. The knowledgebase now of how to port these heads is fairly scarce and the people doing the work have asked for some starting points before they start grinding and flowbench work. I would of liked Carl to do the work but at present he only does complete rebuilds so I have to go the do it yourself route.
Thanks in advance.
Alan
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Post by solo2racr on Aug 9, 2008 23:13:22 GMT -5
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Post by alancase on Aug 10, 2008 4:37:21 GMT -5
Hi. I saw the pics of the heads and the ports. I am not sure from the description if the heads were flowed with a flowbench or if they were just cleaned up a bit and lightly polished. I have got used to everything being worth mega bucks so to see a port and flow job for $150 USD seems too cheap.
Regards Alan Case
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Post by StewRoss on Aug 10, 2008 6:50:18 GMT -5
Here is a page from an old Cycle mag that has a design for a port in it...  SR  |
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Post by solo2racr on Aug 10, 2008 11:34:56 GMT -5
Hi. I saw the pics of the heads and the ports. I am not sure from the description if the heads were flowed with a flowbench or if they were just cleaned up a bit and lightly polished. I have got used to everything being worth mega bucks so to see a port and flow job for $150 USD seems too cheap. Regards Alan Case Your right in that they are not put on a flow bench. The only thing a flow bench will do is tell you how much of a difference there is from when you start and when you are finished. It's doesn't tell you what to do. Just the amount of change of what you have done. A flow bench is good when you have a handful of heads and you want to try different things to see what flows the best and when you have a multi cylinder head and need to match the flow from one port to the next. What you saw is years of experience of what works. Nothing fancy. Just a good cleaning up of the ports, matching to the valve seat and manifolds, cleaning up around the valve stem and, a good finish appropriate to the particular port. Depending on original design of the head, this takes care of most of what can be done. What's left is where the flow bench comes in after trashing a half dozen heads or so to get that last bit. That's where the high cost comes in too. |
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pcnsd
Full Member
Posts: 113
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Post by pcnsd on Aug 10, 2008 14:50:25 GMT -5
Here is a page from an old Cycle mag that has a design for a port in it...
Mr. Stewross - Any chance of posting the entire article? I was just beginning my edjumacation when it suddenly ended and left me wishing for a bit more knowledge...  Thanks. PC |
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Post by StewRoss on Aug 11, 2008 2:34:23 GMT -5
I'll scan it in and get Gary to put it on the system...probably here somewhere if he can... sr500forum.bravehost.com/What do you think Gary? SR |
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Post by alancase on Aug 11, 2008 4:50:19 GMT -5
Thanks. Some good info here. I would like also to see the rest of the article. Regards Alan
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Post by G Man on Aug 11, 2008 17:09:18 GMT -5
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Post by StewRoss on Aug 12, 2008 2:11:26 GMT -5
Thanks for doing that Gary... SR  |
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Post by joneill4 on Aug 12, 2008 14:49:39 GMT -5
So the take home message is Don't F*** With It!...correct? What about a simple polish. Removing as little as possible to get things smooth? I would think it couldn't hurt, but that article was pretty surprising.
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badcat
Junior Member
Posts: 45
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Post by badcat on Aug 12, 2008 15:15:22 GMT -5
maybe solo2's service is right on the money then?
as he says - it's just experience....
Ken
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Post by solo2racr on Aug 12, 2008 15:17:40 GMT -5
Adding epoxy to the floor in place of the clay has never been a good way to add material to a port. Sooner or later, it WILL come loose and trash an engine. Heliarc welding the floor to add material is the only way to do it properly. And that is beyond what most people can do. Adding as much aluminum via Heliarc to the floor is a tricky job. Too much heat from the welding will do bad things to the head. There is another way to get close to their results and end up with a head that has the same theory as what they did without all the welding. I would share but that would be like shooting myself in the foot. Can't give away all my secrets  |
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Post by wotavidone on Aug 12, 2008 22:25:30 GMT -5
Back when I was a boy (Geez I'm staring to sound like an old codger living in the past) guys would convert the intakes on their holden heads by carving a metal insert the right shape and pinning it in place. Holden 6 heads had three intake ports with each port feeding two cylinders. For some side draught carbs, from memory I'm going to say triple twin throat weber setups - but don't shoot me down if it was actually d'ellortos, it was better if each throat actually fed only one cylinder. Something to do with getting a pulse from the interrupted flow or some such esoteric explanation.
So the guys would carve an appropriate infill piece and pin it in place, can't remember what sealant they may have used, then set about porting the resulting separated ports.
There was no doubt about seriously big horsepower gains from the old "red" motors.
OZ members of a certain age will no doubt have fond memories of the old Yella Terra heads, which were good for a minimum of ten percent just by bolting the flow benched big valve head on.
But anyway, if I was going to try to add metal to the inside of the intake, I reckon a glued in shaped piece of aluminium rather than a big slug of epoxy.
Or get an expert to do it.
Mick
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Post by alancase on Aug 13, 2008 4:44:09 GMT -5
Hi Solo2Racer.
Are you the person who does the heads at NR performance?
Is there much advantage in going further than what you normally do, ie raise the port slightly as per the article.
As an aside I was discussing the port with a guy who does a lot of car heads and he said that at a guess the port needs opening at the top and filling in at the bottom but as these heads were not his speciality then he would only be surmising.
Regards Alan
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