Lets raise the roof!

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The Badger
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Lets raise the roof!

Post by The Badger » Mon Feb 12, 2018 3:55 pm

Want to try to see what I can do with raising intake port roofs and would like any advice anyone can give about going about this. I have a gt40 y head, a gm performance parts head and a wealth of the old 289-302 iron heads from the 60's. All of these are just scrap that I was given to practice on so not ruining anything worth much.

Is there any preferred place to start when raising the roof? Should I start at bowl side vs inlet, is there a point of diminishing returns when raising the roof( while keeping same runner size just angle changes)? Any help is appreciated.

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Re: Lets raise the roof!

Post by MTENGINES » Mon Feb 12, 2018 8:21 pm

If you are looking to make just maximum flow. Ad have no intended purpose. Save yourself the time and just remove the intake valve and spark plug. Flow away.

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Re: Lets raise the roof!

Post by englertracing » Tue Feb 13, 2018 1:23 am

I think he is trying to learn some things he can apply to something he intends to run at some point.....

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Re: Lets raise the roof!

Post by JoePorting » Tue Feb 13, 2018 1:56 am

I'd start at the inlet side and raise it .100" then make the roof flat until you hit the elbow of the bowl. That cut is usually always a 5 to 8 CFM winner. The pushrod pinch area is usually always a waste of time. Raising the runner is the quickest way to high flow numbers.
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Re: Lets raise the roof!

Post by The Badger » Tue Feb 13, 2018 8:58 am

JoePorting wrote:
Tue Feb 13, 2018 1:56 am
I'd start at the inlet side and raise it .100" then make the roof flat until you hit the elbow of the bowl. That cut is usually always a 5 to 8 CFM winner. The pushrod pinch area is usually always a waste of time. Raising the runner is the quickest way to high flow numbers.
Thanks Joe, ill get to it. Is that gain going to occur at low thru high and pick up everywhere or do you see it more in a certain lift range?

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Re: Lets raise the roof!

Post by cgarb » Tue Feb 13, 2018 6:15 pm

Why don't you try and sawzall the roof out of one of the heads, then you can use clay to make different shaped roofs without having to grind iron.

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Re: Lets raise the roof!

Post by englertracing » Wed Feb 14, 2018 12:29 am

cgarb wrote:
Tue Feb 13, 2018 6:15 pm
Why don't you try and sawzall the roof out of one of the heads, then you can use clay to make different shaped roofs without having to grind iron.
Now that's an entertaining idea.

I f I got my hands on a flow bench the first experiment I would try is putting clay in places seeing if a port can be shrunk without hurting flow.

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Re: Lets raise the roof!

Post by cgarb » Wed Feb 14, 2018 1:16 am

No doubt you will find this awesome flowing really tall port that you have no material to port into, but surely you would learn what a port wants in short order...way less time and sanity than grinding for hours.

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Re: Lets raise the roof!

Post by mag2555 » Wed Feb 14, 2018 6:35 am

First off what is your valve to valve bowl Throat % at now?

You need to learn to grind out where the restriction is for whatever givien port shape and area you are trying to improve on, also you may soon find that on most heads flow improvements up to .300" lift come by means of reworking the 1/2" or so on either side of the valve and doing something like kicking the roof up will lower port air speeds on the roof path and actually make for a flow loss in the range of .050" to .300" lift!

I agree fully with post 1021 in that you can find out much faster where air wants to go for a given port shape and valve inclination angle by making it smaller!

Do have full access to a flow bench when you need it along with a accurate valve opener?

Most of all if your doing this for fun then enjoy it , but once or if you get to the point of doing a full on rework you will soon see how much effort it takes to 12 to 16 ports by hand, lol!

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Re: Lets raise the roof!

Post by mk e » Wed Feb 14, 2018 9:21 am

englertracing wrote:
Wed Feb 14, 2018 12:29 am
cgarb wrote:
Tue Feb 13, 2018 6:15 pm
Why don't you try and sawzall the roof out of one of the heads, then you can use clay to make different shaped roofs without having to grind iron.
Now that's an entertaining idea.

I f I got my hands on a flow bench the first experiment I would try is putting clay in places seeing if a port can be shrunk without hurting flow.
Or mill it out....but it's the putting it back that's the hard part ;)

As for making smaller...YES!!!!! The hot ticket on rally racing Ferrari 308s was to put the smaller 208 heads on, it ports are about 1/3 smaller and stock flow 1/3 as much, but well ported can match the flow of the larger heads. I had a of the 208 heads set on my flow for development, DM5 loved the numbers that came out so I see why they were popular.

At some point though you run out of air and it's usually easier to just make the engine big enough to need the air the head will flow instead of trying to make the heads smaller....less money and more hp.
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Re: Lets raise the roof!

Post by The Badger » Wed Feb 14, 2018 9:36 am

I do have access to a flow bench, that's why I'm trying all of these off the wall ideas. Just something to keep me busy while I recover from a hernia. As far as air speed I might not understand it completely. I thought as long as the size of the runner was the same it would not loose air speed. am I wrong in this belief? With raising the roof I had plans to use epoxy or possibly weld the floor but after reading up about splashzone that seems a winner, as far as the roof goes if I found something I wanted to try I guess if take a crack at welding and epoxying the roof. I actually like the idea of cutting a chunk of the roof out and reforming it with clay, guess that would be one to try to a few of the ports and see what I can do before getting to deep in this project.

The goal from me doing this is to just see what I can do to a set of stock heads. I've always liked to "redesign the wheel" as my mentor and machinest buddy have always said, probably due to my youth is what I blame it on. Anyway thanks for the input so far and keep it coming.

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Re: Lets raise the roof!

Post by Runit » Wed Feb 14, 2018 10:15 am

I'm remembering a thread about raising inlet ports with a bunch of weld. Chad was going to do the ports. I wonder how they came out?

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Re: Lets raise the roof!

Post by The Badger » Wed Feb 14, 2018 1:18 pm

Runit wrote:
Wed Feb 14, 2018 10:15 am
I'm remembering a thread about raising inlet ports with a bunch of weld. Chad was going to do the ports. I wonder how they came out?
Any idea how old the thread might be? I did some searching for it but no luck.

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Re: Lets raise the roof!

Post by cgarb » Wed Feb 14, 2018 2:15 pm

It was on a set of olds heads if I remember right.

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Re: Lets raise the roof!

Post by n2xlr8n » Wed Feb 14, 2018 2:29 pm

cgarb wrote:
Wed Feb 14, 2018 2:15 pm
It was on a set of olds heads if I remember right.
It was on Olds heads.
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