318 head porting for the average joe

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OK...so here are the ex numbers, keep in mind i used a 1.65 flow pipe...meanwhile when u look at others results 'like shady dell' they do not and even state so...
with that in mind...i also checked peak 'valve wide open' without a pipe to see the diff, very close to shady dell...but I still get 11 cfm more than him=i worked the snot out of the exhaust 'roof especially'...so that means back to work on the intake port so that these heads have a better N/A flow ratio...


the exh flow on my bench stock 'as cast' with 1.65 flow pipe peaks at about 132 cfm
here are the ported numbers from the port shown in my previous post.
-----cfm@lift----28'' w/ 1.65 flow pipe
.100--n/a
.200--96
.300--132
.400--148
.500--159
.600--179
w/o flow pipe, peak is 156cfm....

the exhaust ports on a 318 head basically kick *** for such a tiny port, the floor is sweet...and even with NO port window enlarging they flow fat.
 
Lol,any shop with the word "shady" in thier name needs to be avoided...
 
1wild&crazyguy said:
Today i decided to do 'just the guide'. I shortened it's length where it starts to about a 1/2',
Click to expand...

pardon me for being a complete noob, but can you please explain exactly what you mean by this? Do you mean 1/2 and inch from where the guide begins? If so, what effect might that have on the life of the guide insert?
And where are the updates? I've been hanging out for me DIY tips. (My dremel and carbide burr kit should be here by the weekend)
 
chill out he has already given you several hours of diy and you dont even have the tools.

onewild&crazyguy thanks for theese tips and all your time. you have got me interested in the 318 head now. i have a 2.96 stroke crank and the pistons to make a 288 ci small block. dont see ever using it for racing so your thread has got me thinking about using 318 heads on it and putting it in my boys 71 duster with a four speed.
 
Valvebounce said:
pardon me for being a complete noob, but can you please explain exactly what you mean by this? Do you mean 1/2 and inch from where the guide begins? If so, what effect might that have on the life of the guide insert?
And where are the updates? I've been hanging out for me DIY tips. (My dremel and carbide burr kit should be here by the weekend)
Click to expand...

Noob's dont ask questions like this, so im not buying that excuse. Its obvious u have already formed an opinion on that based on this or that that u've heard or encountered.
'The tail length of the guide...not height', though that will come next...and no you dont need to chop it a 1/2 inch, more like 3/8-TOPS.
Most people will wipe out guides from extreme lift cams without the use of roller rockers before a half inch out of the guides height will, and thats fact.
Not only that...but at the point where u'd think it might...these heads would be way out of app/the worst choice unless rule mandated to be running at that .600+ lift.lol

fwiw An old MP book a friend has even says to cut the entire guide boss out completely, I dont believe that will be needed to get the numbers in this case.


Btw,lol.... How much more are you expecting here?
you have step pics on how to do the bowl/guide/short turn...as well as the simple mods to the exhaust port....and really for this thread, all I have left is to work the entire length of the straight wall from window to bowl, basically widening the port more to squeeze another 10cfm.
If you want bigger numbers than 210cfm from a port that org went 175...then get a bigger valve, it will be easier..trust me.

This is not the only thing i have going ;)

as for now this head flows 196/179 .600 peak and 181/148@.400 & 190/159@.500 about an 84% exhaust flow ratio and with that high side ratio, these heads would be beneficial wether it be with the use of headers or especially the use of exhaust manifolds...which kinda falls in line with idea of this thread=low buck average guy stuff.:evil3:

I will get new port volume numbers up soon and do a lil more int work like mentioned above.
 
1970 La said:
chill out he has already given you several hours of diy and you dont even have the tools.

onewild&crazyguy thanks for theese tips and all your time. you have got me interested in the 318 head now. i have a 2.96 stroke crank and the pistons to make a 288 ci small block. dont see ever using it for racing so your thread has got me thinking about using 318 heads on it and putting it in my boys 71 duster with a four speed.
Click to expand...

Anytime, all of you are welcome...thats why im doing this, for all of you.

Sounds like a fun build and a high winder, and yes heads like this would work pretty good in the entire rpm range...even below.

Im stoked people are interested, it's fun/interesting stuff.imo
 
my small engines teacher once said intake ports shall not be completely smoothed due to roughness actually mixes the air + fuel together.... but it should be smooth just not smooth like a piece of glass... is my guessing/ what i heard true? also what about swirling intake ports?
 
Man I can't wait to start the porting. Some buddys here are very skeptic about the flow I'll get from my heads. Can't wait to smoke them...:burnout:

I'll pick them on fryday at the machine shop already cut to 1.94/1.60, clean and with the new bronze guides.
 
Smooth is one thing, polished is another, this, is what I beileve your teach is thinking off.
The fuel will hit and crash and run down the pot and past the valve and form droplets, which do not fully burn. The un polished heads ports are consideed ruff and help stop this puddle running down the wall.

If your running a racey engine, then this need not apply. The metal can be polished glass smooth.

Ports/bowls should not be left with a surface so ruff that you can catch a finger nail on and tear it off like a far gone brake rotor.
 
consistent surface and shape.

polishing doesnt really gain much in cfm if the surface/shape is already consistent or 'smooth'...and some tests/theories imply it is easier for the mix/fuel to stick to the surface or 're liquify/re connect' to surrounding mix and lose velocity if contacting a mirror finished surface than if contacting smooth yet scratched/grained finished surface, let alone that the heaviest/lower velocity mix/flow is pushed outward...of corse there is always a compensation of rpm induced air speed.lol

boundry layer 101, good read.
http://www.desktop.aero/appliedaero/blayers/blayers.html
 
OK time to add my 3d cent:razz:

Sometimes you can actually gain cfm in the upper lift by simply removing the mirror finish!

My first intake port in my 360 head(that i still haven’t finished) i put a grate polish to the hole port, look real nice. Flowed it again, upper flow drop a bunch at .530 lift and was less then .500 lift.
You could actually here the sound change as the cfm took a dive!

Was told that a ruff texture would help to keep the air attached on the ssr.
Got out some 80 grit emory cloth and took all the shin a way.
Air flow came back at the upper lift, Yeah:blob:...... all was grate.............until i got greedy and when searching for more air/cfm:hmph:

Polishing my look cool, but Don't do it in a intake port!
 
Marcelo Dart BR said:
Did you hurt the flow or hit water?
Click to expand...

Destroyed the flow at .530 and .600 wasn't any better.

You can only push so much air thru a stock port before the air get crazy!
Mild porting can get you some more power. just don't get greedy, and you will be fine.
 
It was any spot in particular?

My plan is to do the same as Justin just going bigger on the throats because I'll use bigger valves. I may try to do a sharper shape on the guide boss maybe. And open the intake ports to the 360 size.
 
With these 318 heads..the only way to screw up with air speed... is to ruin the short turn/cut it out or lay it waaaayyy too far back.

360 heads flow way more and are a diff deal, dont worry about it with ur 318 heads.

If u do as i show, you'll be fine.


btw...the guide boss shaping was an experiment, i have another port on this head where all i did was lower it's height...but left it's length and width...and it does 207cfm @.550. I was just doing this to show what that would effect.
 
I've read the throats should be about 85% of the valve diameter. Can I open the intake throats to 1.65" (85%-1.94") without risks of hiting water? and about the exhausts?
 
This is my first attemp at head porting. These are 1970 open chamber 318 heads. I did most of this work about two years ago and the heads have been sitting out in my shop since. There is a little flash rust on everything in the photos and the work you see here is not the finished product. I am an average Joe just trying to learn new stuff and do it on the cheap. 318 heads are like starfish; if you ruin one, another will grow back. I'm open to constructive criticism on the work you see here. Any helpful advice will be accepted graciously. There was a lot of seemingly excess material on roof of the exhaust port before. I don't know how much further you can go on these before you hit a water jacket. At this stage, I think I just need to smooth them out and call it good. The intake side ports have all been gasket matched and just need cleaned up. It looks like I could probably blend the guide bosses a bit more and smooth up the rest of the port. No valve job has been done here yet. If they turn out well, they'll end up on a mild performance 318 backed by a four speed transmission in a '66 Barracuda. Hopefully this will happen within my lifetime.:burnout:

318 Head Porting 70-1.JPG


318 Head Porting 70-2.JPG


318 Head Porting 70-3.JPG


318 Head Porting 70-4.JPG


318 Head Porting 70-5.JPG
 
Should the casting on the roof of the combustion chamber be blended, or should I stay away from it with the die grinder?

318 Head Porting 71-1.JPG


318 Head Porting 71-2.JPG


318 Head Porting 71-3.JPG
 
the plug boss can be blended some, i have seen heat cracking there...though the crack go's nowhere...but 1st put a plug in and just smooth and blend to its edge.

the area between the int/exh valves can be blended, be careful of corse...
the area where int valve is seemingly shrouded I would leave alone for now.
I have played with that area in the past and it caused ssr loading in that area that seemed to pull the rest of the turn with it and the flow at lift had a blip afterward.

U can however blend all the way around the exh valve on the chamber side and rid the top cut lip.

the port window doesnt really do much for flow, it can stay stock and flow 200-205cfm, its the straight wall & pinch that seem to net more so than grinding a 360 sized window.
You can stay with the 318 window/gasket and just grind the pinch protrusion straight with the windows edge on that side, on the straight wall/divider wall side u can remove a lot from all the way to the bowl, grind a bout .030 out of it, but leave the flange side alone...as in dont thin the gasket sealing surface, go just beyond it.

you're doing a good job btw, and even a lil conservative at 1st glance...which is smart till u flow some of the work u do to know its working.
right on.
 
Thanks for the feedback wild&crazy. It will be a while 'till I get back to this project but at least I have a good idea where it's headed. I'll post updates as work progresses. Don't hold your breath though. :D Great thread by the way. I'll go back and look at the pics you posted and maybe that will give me some more insight on where to take it. Thanks, Drew
 
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