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Discussion Starter · #1 ·
So I was looking through Stan weis’s flow page and for stock 429 heads shows “ok” flow and ported shows 305/175…
This got me thinking, when I’m using specs for my desktop dyno, the 315/180 quoted in the 460 hp chart makes lots of power, but how close is that to a regular guys porting??

I guess my question is, how hard is it to get 300cfm from an intake?? Anybody can clean up a port for that or is it “top end porters” can only do that?
 

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So I was looking through Stan weis’s flow page and for stock 429 heads shows “ok” flow and ported shows 305/175…
This got me thinking, when I’m using specs for my desktop dyno, the 315/180 quoted in the 460 hp chart makes lots of power, but how close is that to a regular guys porting??

I guess my question is, how hard is it to get 300cfm from an intake?? Anybody can clean up a port for that or is it “top end porters” can only do that?
Jim,

Average Joe six pack can get 290 300 / 160+ pretty easy which helps significantly if he simply follows our online instructions

Budget ported stuff is typically 305 to 315 / 180 ish. Only because I can do it in my sleep.

Large valve highly developed stuff (I don't do it any longer) will go 345+ /195 to 200 w pipe.

Work with in 1.5" of the valve offers the most bang for the buck.

Gasket matching and port matching while ignoring the aforementioned is as useless as tits on a boar.

If you look at the port exit size on a performer intake, for example, and compare it to the actual cross section about .375" into a passenger car casting they are pretty damned close.

I am still baffled by the number of folks that only address the exhaust port leaving 20+ hp on the table.

Finally:

With a simple performance valve job, properly sized choke via serdi cutters and knocking down the sharp edges...
Early castings will easily support 415 to 420 hp with reasonable cam timing. D3's a tic less due to smaller exhaust port cross sectional area at the short turn.

What it boils down to is how much work is necessary for the power I am building and the intended use???

Our budget ported small chamber stuff is making 515 to 525 hp with modest cam timing similar to the RPM package by Eddy or the same cam in non modded SCJs.




Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Parkland Auto Machine
 

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460jimbob the first thing you need to do ( and this is for any type/ brand of head) is to access what you have now which will tell you how you might improve the ports.
To do this you need to know how a port is basically geometrically designed.
This will then allow you to take simple measurements and make simple templates number1) see how your port(s) shake out now and number2) these templates will guide you in any porting work you may undertake.
Here is a geometric drawing of a known port.

in this diagram note the two circles, one Big and one smaller one on its center.
This port uses a 2.11” valve, the minimum diameter of the valve bowl throat as you can see is 1.60”.
This is small for this 2.11” valve and is well under the 85% minimum that would be a good start to using this 2.11” valve.
The maximum that a throat should be for any head, and yes even flat out race heads is 91.5%
Back to this diagram note that the small inner circle I talked about before is a radius of .800”, this then is the same diameter as the throat which is 1.60”.
Also note that the bigger circle is that .800” plus the 1.60” throat for a total of 2.400”.
From my discription here I hope you can see that any increase in throat size will make for these circles to get bigger .
Here are two more pictures of a throat template set on this geometric drawing and a throat template made with a machine screw for a handle.
These templates can be made to help you find where the main restriction is in your ports .
The usage of inside snap gauges will be of great help to you also, so plan on getting a set along with a cheap plastic dial caliper if you do not have such.

I gotta run now, but I bet you will now have further questions to ask.
 

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Stevenm, I really like the throat templates. Seems like a good way to stay consistent. Thanks for sharing.
 

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Discussion Starter · #5 ·
Love the templates and thanks to both of you for responding.
So, some background..
I have the tooling and experience to do 5 angle valve jobs and replace guides(all neway stuff) I’ve done porting and gasket matching for 35+ years.. and no, I’m not even in the same ball park as the mad porter😂😂.
That said, it’s good to hear that the early castings will support that much flow. I ground/smoothed everything out like anyone else would, just don’t have a flow bench.

I guess the last thing I would say is, if the early castings will support 400hp I’ll be happy. I’m trying to make do with the stuff I have laying around.
I need To run 11.5 at 3200# which is around 400hp, the rest is gravy!
 

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Discussion Starter · #6 ·
Oh, and Steven, the templates are great, I cut up some sbf heads and then made plugs to fit the port out of this glue/putty **** my kid had, helped a lot with porting. Now I need something for bbf heads and I like your idea!
 

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Hi again JimBob and Stude.
I posted yesterday what I did in a rush and there’s much more detail I can give then what I put up in terms of these heads and any head in general.
First let me say this, the last time I ported a set of iron marine heads was 2 years ago and my arms are still sore from flipping them around to port them and then hump them onto the flow bench!
If your building one of these motors I would pick up a part time job so I could get a set of aftermarket aluminum heads just for the darn weight savings, no less for the added flow they have out of the box, Dam these heads may even weight more then iron BBC heads do!

jim these heads intake ports in stock form flow more then enough to make 425 hp, this only takes about 225 cfm out of the 260 cfm that these heads flow, it’s the exh side that truly sucks on these heads as you may or may not know.
With the ok exh ports that the iron 351 4bbl heads have I can’t believe Ford ever approved these to go into production with there stunted 128 cfm of exh flow which makes for a pitiful 50% exh to intake ratio and a engine that runs hot, especially if it’s under 9.5 to 1 compression.
Here’s some photos and info of the 460 marine mule head I used to develop the ports I reworked those years ago.
I increase the exh valve size to 1.75”.
The average throat diameter got taken out to 1.456”, which still makes for a small 83% throat to valve ratio.
I did this deliberately so I could pick up a nice fat amount of low lift flow and a good amount of high lift flow.
The exh port in these heads are so choked off with the size of the valve guide boss no less the huge air injection boss that in total it took me 3 hours of very hard grinding to get the port to how you see it in these photos.
The result was a peak flow gain at only .500” lift of 185 cfm, which is a 53 cfm gain over stock.
In fact the reworked exh port is already flowing more at at .225” lift then the stock port did at .550” lift.
The proper use of the 1.750” valve made for a 20 cfm flow gain even way down at .100” lift even.
The real good 3 angle valve job that I was able to put in by means of the larger valve had a lot to do with these flow gains, and the bigger valves help out in the compression department also.
Note that I did not even gasket match the exh port, as there is no need to do such .
Even a novist home porter with the right cutting burrs and pan cake type cutting stones can replicate what I did here as time input should not be a issue.
If need be for flat out racing purposes along with enough compression I am sure that these exh ports could be reworked to produce over 225 cfm, it’s just that some of the low lift flow numbers would have to be given up.

I am out of time again, but I will post more this afternoon about how to make and use the templates that I have shown here, as I think you folks might have questions about the details of there usage.

later!
 

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Discussion Starter · #8 · (Edited)
Wow…..
I gotta get out to the garage and check the porting I did many years ago to the c9 heads. Definitely not as pretty, I might have hogged out too much. I’ll get some pictures too.
Thanks again Steve.

Edit: Just thought too, I was going to run stock size valves but would just 1.75 on the exh be worth it? I’m guessing yes.
2.06/1.75 has a nice ring to it😁
 

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Wow…..
I gotta get out to the garage and check the porting I did many years ago to the c9 heads. Definitely not as pretty, I might have hogged out too much. I’ll get some pictures too.
Thanks again Steve.

Edit: Just thought too, I was going to run stock size valves but would just 1.75 on the exh be worth it? I’m guessing yes.
2.06/1.75 has a nice ring to it😁
An OEM size exhaust valve will flow near 180 cfm with pipe. More than adequate for 400 hp with an IE split of 12 to 14*.

When using a larger exhaust valve the choke, cross section at the short turn and through to the exit need to grow to utilize the additional valve area.
This is the point where port volume and cross section are more important than velocity. Say at 650 to 800 hp. I am done with that type of class racing port work.

After 25+ years of snorting iron dust...
Pretty doesn't make power. Air flow at the correct velocity however does.

You get to a point with the passenger car heads that proper seat, choke and Short turn shapes get you good flow say 315 cfm with a 2.11" intake valve while increasing low lift and average flow. At this point chasing higher peak numbers hurts low and mid lift offering lower average flow.

A larger valve, larger choke at 91% or so, more cross section in needed areas to slow the column as it transitions to the bowl will allow greater total flow and peak numbers. Again getting to aggressive at the short turn radii will offer greater peak numbers but starts to kill low and mid lift killing average flow.

Average flow makes power.

I've always flowed the heads with the intake of choice bolted on. Different intakes require slightly different shaping at the intake runner entry. Especially so with #4 and #5 ports.









Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Parkland Auto Machine
 

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Discussion Starter · #10 ·
Exh flows 180cfm stock, and that’s enough to support 400hp.
I’ve always held the assumption that max hp is double the intake flow. Obviously the exh can’t be held in the same way.

Next thing is the 1.6” “plug” to confirm port consistency, love the idea and simpler than what I am doing. I’ll make one even though the c9 heads are already ported, just to confirm what I did. (Confirm good or bad😂😂)

My final “concern” if you will, is that I’m using what is available as opposed to buying “exactly correct”. I already have the ported c9’s, my cousin has a cam/lifter and chain set from 15-20 years ago, brand new in the box, that I’m getting for $100. The 460 I’m using was given to me because my other cousin sold a beautiful 80 f150 with my tach in it and gave me the engine as compensation on my 5” tach. Then I look on the hp chart as well as Stan weis flow charts and am concerned I’ll be lucky to hit 300-325hp from it!


.100. .200. .300. .400. Etc
58/42117/88174/117196/131224/137239/141247/142-
 

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Discussion Starter · #11 ·
So 460, ported c9 heads, stock intake and 750dp. Homemade headers 1 3/4” and the cam from what I remember from 20 years ago when I saw the cam, it was a 4x4 cam and at the time it reminded me of a 270 mega or 270 magna cam or a bit tamer. I’m guessing 204ish at .050 and .512 or so lift.

add all that up and run it through my desktop dyno and I got 325-350hp with 600# or tq. So now I have to calibrate my desktop dyno to get it more accurate. I’ll copy the engine parameters of some known engines (Richard holdener on you tube) and see how close I am. Richard did a stock 68 460 and got 350hp, I’ll have to see what I get.

And yes I know garbage in= garbage out, that’s why I want to see if I can make this as accurate as I can. Truth be told, if it makes 300hp or 3000hp it doesn’t matter as far as et goes as it’s a bracket engine. But I want to either be the quickest in my class (11.5) so I’m always chasing or the slowest (13.49) and always be chased. Running a 13 sec pass in a 460 fox body while others are doing it with 302’s is not what I’m looking for though😂😂😂
 

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The oem exhaust port does NOT FLOW 180 cfm. It can flow near that with port work with the OEM valve size.

We get 135 ish on our bench with an untouched oem style port and valve job.
I've outlined on our porting site what each mod offers for flow.

Use an appropriate dual pattern cam.






Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Parkland Auto Machine
 

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Before I get deeper into how to make and use templates and measuring gadgets I would like to help you guys out by taking a step back from what I was going to post and reinforce the info and the kinda direction that Scotty was going for.
This once again can help you access things and where you need/ want to go with the work.
There is a very simple carved in stone formula that is this Dx.18.
D is just valve diameter and working the formula gives us a important lift number.
So let’s say we are dealing with a 2.06” intake valve.
We then multiply this by .18 for a result of .370”.
Ok, so why is this so important, well this is the amount of lift and in turn flow that is controlled by the area and shapes on each side of the seat to the tune of up to 3/4s of a inch or so.
Up to this lift point the amount of air passing into the chamber is taking the path of least resistance and is really not yet following the basic size and shape of the port that you have going on back to the flange.
This is called the change over point and can clearly be seen on the flow bench because the vertical manometer fluid column will start to lightly bounce around.
The fluid is bouncing around because right at .370” lift the air mass can not decide what to do.
Now with this info you should see how important the valve job used is and the valve bowl shape and the shape that the chamber is in this .370” lift range.
Another good way to look at this would be if let’s say you where running a lift at the valve of .500”, well .370” is 74% of that .500” so where talking about a big chuck of the total amount of air ingested into the cylinder!
It should be clear from this how important the valve job is because for example a 3 angle valve job can in compass 3/8” of a inch out of that total 3/4” on the back side of the valve that I talked about a few paragraphs ago.
Here in this simple drawing I made of the cutaway of a short turn is a example to keep in mind of what parts of a short turn control what lift range to a large degree, so this info is pretty well cut in stone also.
In my drawing here divided up the short turn into 3 sections, top, middle and lower.
The top or crown section has the most effect on high lift flow numbers, the lower section which includes the valve job and sometimes even the chamber lip as in some Heart shaped chambers controls to a great extent the amount of low lift flow.
And the middle section has a effect on both low lift and high lift flow.
That’s enough for now.
 

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Discussion Starter · #14 ·
I am learning so much…. And I’ve ported and done valve jobs for a lot of years. I guess this proves if you give a monkey a cbc machine, he can make something better but not understand why other than”bigger”.
The how and especially why are crucial to understanding what makes power and why. If you understand that, then you can make mods to prove/disprove hp.
Thanks to both Scotty and Steve for providing free info to people they don’t even know.👍🏻

Dx.18…… who knew? Lol!!
 

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Air just like water will always first try to take the path of least resistance.
I river once it’s forced to move more volume then can be done by means of least resistance will start to carve out its banks to move that added volume, air can not carve out metal!
Another big point to always keep in mind when reworking any part of a head is velocity.
The more air you move thru a given size area the more the velocity will go up.
The detail to this is that once a certain velocity level is reached air will not follow around anything greater then a 15 degree bend / change in direction.
To make it do so the air mass needs to be expanded which in terms of head ports means slowed down back to a non critical velocity point.
Hence in terms of a intake port the expansion from a port runner into the valve bowl and then again thru the valve job and out onto the chamber.
 

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I have the time now to explain the making and usage of the templates I have been talking about.
Just to review and use a modified phrase, the throat of the valve bowl is the tail that wags the Dog so to speak.
For any given valve size to start to be effective in the amount of air that it can pass the throat needs to be a minimum of 85% of the valve size.
For a novist porter with no flow bench at home I would suggest not to exceed a maximum throat size of 88%.
There are a bunch of reasons for this, but first and foremost it will keep you out of trouble.

I make my throat bowl templates out of .060” sheet plastic from a hobby shop and also from old valves that are big enough to be ground down on a bench grinder to the throat size I am in need of.
The first step if your going to enlarge your current throat size is to use a old valve of the stem size your heads use.
This is because when you make the throat bigger it must be done so in a concentric manor, at least for a good amount of the bowl size increase.
Whatever size template your making needs to have a flat side equal to 94% of its diameter
So for example a 1.66” throat template will have flat that is 1.560” wide.
Also transition from round to each end of the flat needs to be softened a bit .
What you end up with is like what’s in one of my pictures here, and another picture shows a 1.66” template being sunk into the valve bowl of this pair of Buick nail heads that I am currently porting.
The new throat diameter needs to at least go in deep enough into the valve bowl until any cutting that was having to take place on the short turn has stopped.
This is because some heads / ports have deep bowl and you can go in much deeper and some bowls are shallow.
If you stop cutting just when you clear the short turn, then this will help to keep you from cutting thru a port wall possibly.
I have adjustable seat cutters that I use to open up the bowls and this saves a heck of a lot of what would be tuff grinding .

I would suggest that if your shooting for more then a .040” increase in throat diameter that you have a machine shop open the bowl up for you.
In one of my pictures you will see the lip from the start of my rework of making a throat bigger.
One you have a good start on the bowl size increase the new needed arc of the short turn needs to be put in because the roof and port side walls will need be cut to compliment the new throat size.
You can make a short turn template out of plastic or sheet brass or aluminum.
I would suggest that you make a series of 3 progressively larger templates to help guide your porting .

there is a bunch more detail I need to get into about the correct usage of these templates, and I will post up more this evening.
 

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Hi all.
I have been thinking about doing a series of short videos to instruct on how to use these templates I have been posting about since I think doing such will help more .
I will have time to do this over the weekend.
Is it possible to post short videos on this site, or do I have to link to them?

thanks in advance!
 

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Great discussion... following. Thanks for sharing.

I'd encourage posting a link to a video on Youtube or comparable site so the video can be as long as needed to show the level of detail required. On this forum, I've only seen 10-15 second videos... or shorts... maybe due to file size restriction.
 
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