SBC Head intake port shape

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Hap
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SBC Head intake port shape

Post by Hap » Tue Jun 05, 2018 2:24 pm

Was trying to pick the brain of my head guy the other day. He mentioned that intake ports on non canted valve SBC heads have angled floors (side to side).
This pertains to 1st gen SBC heads, non vortec.
He said the angled floor is an intentional design and not dependent on the intake manifold design.

Would appreciate any information you all are willing to share on this.

This is totally new to me as the 23 degree heads I've previously ported with templates (461, Dart 180s, 200, GM Bowtie); recall 4 of the intake floors have some angle and the other 4 were close to flat.
But all of these heads were never flowed before and after, so I was porting in the dark so to speak.

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Re: SBC Head intake port shape

Post by JoePorting » Wed Jun 06, 2018 3:14 am

I like flat but have seen some people use angled floors. I haven't tried or flowed angle floored ports, but don't think there's much of a difference. * has some interesting floors. Maybe he can post a few pictures if he's still out here.
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Re: SBC Head intake port shape

Post by midnightbluS10 » Wed Jun 06, 2018 9:55 am

JoePorting wrote:
Wed Jun 06, 2018 3:14 am
I like flat but have seen some people use angled floors. I haven't tried or flowed angle floored ports, but don't think there's much of a difference. * has some interesting floors. Maybe he can post a few pictures if he's still out here.
I think he's gone from here unfortunately.

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Re: SBC Head intake port shape

Post by jeff swisher » Wed Jun 06, 2018 2:35 pm

All the heads I have seen have an angle to the floor near the short turn. even the early 283 2 barrel heads.
I found if i flatten the floor or take the angle out i get more fuel wash against the chamber near the spark plug..
Kind of lost the hook and swirl.
Leave the angle and I do not need to kick the chamber out as far near the spark plug on the intake valve side.

I still kick the chamber out.. but I leave as much slant in the short turn in intake side as i can.

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Re: SBC Head intake port shape

Post by mag2555 » Wed Jun 06, 2018 2:48 pm

The floor over the short turn on these Heads you speak of has that tilt to it to speed up the air flow on that push rod side of the port.
What's going on is that high velocity air wants to go straight and not curve back over to the push rod side of the floor and short turn.
This means less air is passing over that side of the short turn, this lesser amount of air is flowing at a slower velocity so this lower titled floor shape speeds the air up to better match what's going over the short turn from the center of the floor back on over to the straight / common wall.
The net result is more air flow.

Hap
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Re: SBC Head intake port shape

Post by Hap » Thu Jun 07, 2018 12:43 pm

Appreciate the information!
Having the floors on the short side higher makes sense now.
The specific heads are Trick Flow Super 23s; 195s with CNC chambers.
From what these old eyes can tell, floors on the outer two runners are flatter vs. the inner, so maybe Trick Flow did this on purpose?

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