Picture of 340/360 head porting....Mistakes?

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Do you now have the die grinder and flow bench closer to each other?

If you’re still in the R&D mode, you could just start in on another cylinder, do what seems like a straightforward normal port job on it...... flow it before and after...... maybe a couple tests of specific changes along the way...... see how it compares to the one with all the mud in it.
 
I have a dye grinder and air at home and a unfinished flow bench........well the bench is all but finished.....but the power to safely run it is not.

So what is your definition of Throat and Bowl
 
Well, how I think of it is......
-the throat is the area where the valve job transitions into the bowl.

-the bowl is the area father into the port......closer to the end of the guide boss.
On stock as cast heads, it’s usually smaller than the throat.

The trend I’ve been seeing for the last several years with cnc ported heads is to have the max bowl diameter be close to the same size as(and sometimes bigger than) the valve diameter.

On unported aftermarket heads, the bowls and throat are often about the same size....... but there are some heads that don’t follow that trend at all(Ede BBM std port Victors being one example. The bowls on those heads are much smaller than the throat).
 
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Ok thanks for that.
My measurements are at say the bottom of the 75 degree cut.
 
Well, depending on how far down that is, it could be throat, or bowl, or in between.

On heads where the bowl is bigger than the throat, it’s easy....... whatever the smallest measurement I get is, I call that the throat.

If the bowl is smaller than the throat........ I pick an area near/adjacent to the end of the guide, and call that the bowl diameter.

If the bowl is bigger than the throat, I find the largest diameter I can...... and that’s the “max bowl diameter”.

On a lot of newer cnc stuff, the bowl can be quite a bit bigger than the throat(over .200” difference).
 
I did grind a bowl larger than the seat on the prp side but it was a epic failure. as in Screeching Loud! port Lost 20 cfm and my Velocity probe said that the air was coming back up the port on the ssr prp wall. Filled it back in and problem when away. once again it look real good....but NO!
 
Cudafever said:
Ok thanks for that.
My measurements are at say the bottom of the 75 degree cut.
Click to expand...

I'm going to rephrase this.

My bowl/ throat measurements were alway the largest part under the valve.
EDIT: SMALLEST part under the valve
 
Well, if the bowl is shaped like a funnel, that measurement would be pretty far away from the seat, and wouldn’t be what I considered the throat.

But I’m certainly not the last word on porting definitions.

To my way of thinking, the bowl and the throat are referencing different parts of the port....... even though they’re in close proximity to each other.

For example, I just updated some Indy EZ’s a couple of weeks ago.
I increased the intake bowl diameter...... but didn’t increase the throat diameter.

D4614533-99A1-4AB5-8FA9-A2C46B909830.jpeg
 
Cudafever said:
I did grind a bowl larger than the seat on the prp side but it was a epic failure. as in Screeching Loud! port Lost 20 cfm and my Velocity probe said that the air was coming back up the port on the ssr prp wall. Filled it back in and problem when away. once again it look real good....but NO!
Click to expand...
You dont want to get wild on that side of turn and wall. Just to get more cross section, but even then you have to balance it..or itll take over and half the port is torn from the straight wall right from the entrance. It gets all fkd up.
 
Throat, or the pertaining to that I keep most account of is the area just before the guide at the short turn.
The "bowl" is essentually venturi'd on the far side in a max effort. You can create issues doing this or that but when you keep a venturi shape on the far side, which is bigger bowl than seat, it does flow more air.
A 915 278@.500 and 906 280@.500

1582318667115_IMG_1000.JPG


1582318656003_Photo 843.jpg
 
So looks like i need to add another spec to my notes when i continue.

To my way of thinking, the bowl and the throat are referencing different parts of the port....... even though they’re in close proximity to each other.

Still trying to grasp this concept.
 
The short turn only accesses the throat...............and the wall/roof access the bowl?????
edit to fix
 
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Ok here we go.
IMG_2094.jpg


Hmmm well you can't read that vary well....
ok at the throat starting from straight up and down and then going clockwise.
1.736,1.760,1.674,1.704
The Bowl is larger @ 1.914,1.943,1.816,1.807

All measurement are inside port window at PRP.
top top to bottom 2.047
top side to side 1.037
Middle ............1.049
Bottom........... .930
 
Well...... I would start by getting the throat closer to 90% of the valve(your average is 85% now), and flattening(side to side) & laying back the short turn.

As I said earlier, I’ve never found any success with that heavily rounded floor shape.

Even on stock Pontiac heads, that have the floor pretty rounded like that from the factory..... I’ve had success buy broadening that area.
 
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Just a little clarification.
When you say laying back....you are referring from the seat/65/75, to the floor right.
or are you referring to the ssr floor down. I know in the end they are the same. Just trying to see which side you are looking at.
 
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Something like this.?

Drawing.PNG
Pardon my jaggedness, hard to draw with a Mouse.:)
 
Go more straight up on the straight/common side from the 65...then lay it back a lil near the top, get a lip going 'to yank the air' closer to the port window than the dog leg side.
 
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Still trying to grasp the lay back concept.
You say cut straight up from the 65...... So your talking a vertical wall straight up to the seat aka 45, of the common or straight wall.
So to say it differently, if it was being done by a cutter, the common wall would go 45 seat,90 wall, then 75 bottom cut?.......or maybe eliminating the 75 all together

Or when you say go more straight up your meaning from the port window side of the ssr at the common wall and more straight out, not curved up to (or down depending how your looking at it) into ssr in the bowl.
 
Cudafever said:
Still trying to grasp the lay back concept.
You say cut straight up from the 65...... So your talking a vertical wall straight up to the seat aka 45, of the common or straight wall.
So to say it differently, if it was being done by a cutter, the common wall would go 45 seat,90 wall, then 75 bottom cut?.......or maybe eliminating the 75 all together

Or when you say go more straight up your meaning from the port window side of the ssr at the common wall and more straight out, not curved up to (or down depending how your looking at it) into ssr in the bowl.
Click to expand...
In your upside down pic, the right side of the short turn, get steeper then lightly lay it back and then go from the port window and lower and descend just a tad to meet the short side work mentioned . You wan to have a mildly descending ramp to the short turn. We are essentially evening up the distance and pressure on each side of the turn as we go for more air flow
 
Look at a j head, the gutter in the short turn.
That's the hump you knock down on the straight shot to the s turn.
Even it up, dont work the dogleg side or very little.
 
still thinking on this. trying to paint the picture.......so to speak
 
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