318 head porting for the average joe

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Badart said:
Dang those flow numbers are pretty sad. LOL. This thread will help so many guys that ask the question "Should I run my stock 318 heads". LOL Did you happen to CC them? Just curious. Why is there such a small increase in flow numbers from .300-.500, just the tiny runners?

Good to have you posting again.
Click to expand...

Thanks man.

124cc stock intake port, chamber measured 68cc

The ports were designed to max flow under .450 lift, thats where the factory cams were, so thats my 1st idea for 'as cast/smoothed'.

Once i do the short turn & bowl work, the numbers will start picking up above where the original design intended.
 
Very cool thread,nice to see you document this for everyone.I ported a set of 318 heads for a street 360 build with awesome results.I ended up raising the legnth of the roof to the stock 360 port size and reworking the short turn and opening up the bowl to 90% of the intake.Also did the same as you on the exhaust side,original 1.78/1.5 but they did have a serdi valve job.The heads went on a stock 360 shortblock with an actual 8.6 compression,ported performer intake (360 size runners/mild plenum work) 600 holley,cheap headers and an xe274 and was a screamer,upper 12's all daylong with 3.23s in a 70 dart!.
 
lead69 said:
Very cool thread,nice to see you document this for everyone.I ported a set of 318 heads for a street 360 build with awesome results.I ended up raising the legnth of the roof to the stock 360 port size and reworking the short turn and opening up the bowl to 90% of the intake.Also did the same as you on the exhaust side,original 1.78/1.5 but they did have a serdi valve job.The heads went on a stock 360 shortblock with an actual 8.6 compression,ported performer intake (360 size runners/mild plenum work) 600 holley,cheap headers and an xe274 and was a screamer,upper 12's all daylong with 3.23s in a 70 dart!.
Click to expand...

Smart man! The valve job is THE most important key to a cylinder heads ability to make power.
 
Cool to know,this is a great idea.Thanks,we need to sticky this thread.
 
ditto....lol....I saw up to a 7 cfm increase in the lower .100-.300 lift range when going from a crummy valve job to a good valve job.

Tomorrow morning ill test what ive done today and post numbers by the evening.
 
1wild&crazyguy said:
ditto....lol....I saw up to a 7 cfm increase in the lower .100-.300 lift range when going from a crummy valve job to a good valve job.

Tomorrow morning ill test what ive done today and post numbers by the evening.
Click to expand...

Just as important as flow... The highest quality work, done with the highest quality equipment, means the cylinder seals totally and smoothly. That reduces valve bounce and valvetrain harmonics and the chances of breakage.
 
Awesome thread ill have to learn as well to do my 302 heads. Since I wouldn't be able to take them to you to get them done

I wish I can tho...... Stupid bills but maybe when I sell my truck lol
 
Sorry double post but since I can't delete it ill ask a question ..

Lead69. So basically if I were to put 318 heads, air gap int, 650 pd, and a good cam on a 360 block it would be a 12 second motor? Just curious
 
Btw...let me give an example, something for those of to chew on...a different view..

If you port a head 'like im doing' to flow another 20-30 cfm over stock throughout the whole lift range... which would u rather have, the head that flows 20-30cfm over stock with a run of the mill VJ that seals....or the the stock head with the $250+ VJ that flows the 7 cfm over stock...
In that case, the fancy valve job is not gonna make the power that the porting is...and is NOT the most important thing.

What is important in the long run with cylinder heads...is the ability to seal the valve and good air flow, period.

I have a set of X heads. I took those X heads down to a race shop called total performance, they have a serdi and custom ordered multi angle cutters that they use and claim to make another 12cfm from the existing port....So i go in there and bring my X heads that flowed 225 'ish up to .600 and had them do they're 5 angle that included chamber top cut....The heads picked up flow to 240......but they were now done @.450 lift and dropping off....which is where most of these stock heads stop and go saturated or turbulent ootb.....
The more angles....the faster the air at the seat...the faster fps, to a point...turbulence occurs and all that air backs up afterward.

The last ''good valve job'' I had took the flow down .040 in lift...it sped the air up which is usually good, but not when ur already on the verge moving big low lift numbers..
those heads flowed 77cfm @.100 & 200@.300 about 250cfm@.400 'even before the better valve job'....and they are nothing but old ported factory iron, blowing the doors off of heads that cost over $1500+, but i digress..

All of these heads will do the same or so close that it all simply ends up as preference, like whats ur favorite color...it comes down to how much you can do, want to do..cause the potential is there as well as the limitations, most new 'bolt on' replacement heads all have to work within the same constraints as the factory casting. the push rods are in the same location, the valves at the same angle, the only thing they can really do port wise is cast a lil more meat 'where they can fit it' and cast it with less to remove...like if the factory had ported up 360 head to flow 250-280cfm and then made a mold, cast it.. and sold it in that form.

This thread is not really about brands,whats the best head, someones opinion of what they think is more important, or even valve jobs and 360 heads...

Its about a guy with a set of 318 heads who wants a cheap way to up the hp/air flow on his motor and not break the bank or get over involved.
Im showing u how to do this, how to pull up ur droors and get'r done, it's not hard...once u learn you'll be asking urself why in the hell did u waste all that money on that ricky racer over hyped performance machine shop that bleeds u dry everytime u walk in the door.

BTW most of you who send me pm's about having me port ur heads...I already expect that ur really not. And all u guys with big bucks to spend...I know ud rather go to the high dollar shop and talk to the magazine guy cause spending more makes some of u feel better about it...and I dont mind, really........thats why im giving it away here.
 
1wild&crazyguy-

Your doing a great job on a very interesting subject here.
Have you flowed a set of 302s with/without work?
What about 308s?

I have heard/and read that "stock-As Cast", no work done, 308s flow the best...is that anywhere near true?

I have some more specific questions I am going to PM you...but ^ these are still inline with the topic.
 
This is a great thread and has the potential to help a ton of folks here. I am curious what flow bench you are using,and at what setting,ie;24",28" ?

Very cool idea. Perhaps there will be more heads to come? Are you willing to accept heads from members here for flow testing?
 
I have heard/and read that "stock-As Cast", no work done, 308s flow the best...is that anywhere near true?
Click to expand...

The 308's i have had alredy been polished, so as cast I cant say...
I can tell that the polished 'with nothing else done to them' 308's i have flow 232cfm.
The stock 2.02 J's I have 'as cast' flow 228cfm.....so it's close but it could be the polishing imo..cause the port looks IDENTICAL in every way except for the the push rod pinch being more intrusive...which kinda tells me the push rod pinch is not an issue in stock form, so in that case... to work that area of the port 'push rod pinch' would be simply slowing the air down...and counter productive, even if it yeilds 3 cfm more.
As for the exhaust...they flow more at the lower lift, after that.. the roof is cast so low that just a lil port work is required...then they flow big, compared to a lot of port work to get about the same with an older head, simply is in better form to start with.

back on topic..
After I do the next round of numbers for these 318 heads, I will start on the exhaust ..stock and modified with step by step pics.
 
One more note, i would like to add to all you, with that grinder in you hand for the first time...GREED WILL KILL YOUR HEADS!
Keep that in mind when your doing you heads. when you start to change the port shape and design, your standing on thin ice! ask me how i know:banghead:

Cleaning up the casting flaws and imperfection, is easy and simple prosses that net you more cfm/power

There is alway the one car or one eng that is completly stock, that just runs gooood. this is one of those reason why.

Happy Grinding :shaking2:
 
needsaresto said:
This is a great thread and has the potential to help a ton of folks here. I am curious what flow bench you are using,and at what setting,ie;24",28" ?

Very cool idea. Perhaps there will be more heads to come? Are you willing to accept heads from members here for flow testing?
Click to expand...

Flow performance, 28'' depression, i check its calibration with a plate
I test before and after so that the gains can be seen for what they are... not just numbers.

If I dont have the particular head to give info for, then yes, PM me.
 
duster731 said:
Sorry double post but since I can't delete it ill ask a question ..

Lead69. So basically if I were to put 318 heads, air gap int, 650 pd, and a good cam on a 360 block it would be a 12 second motor? Just curious
Click to expand...

For me It is all about run what you brung and my idea was to build as much usable power in a relatively low range with limited compression ect.I already had a set of low miles 318 heads collecting dust that had a nice valve job on them,they were also cc'd at 64 to help get "some" compression out of the stock 360 vs. the huge chambers of a 587 head ect.The machine shop I use does everything with a serdi and custom bits and if the heads need nothing else it is a hundred bucks-it is a steal!,but is not necessary to get in the range of h.p I did.I figure at most the car would lose .1-.2 in the quarter if I had to guess between a good sealing factory job and a serdi-but this is as directly related to my combination of limited parts.This is not that hard to do with some research,knowledge and desire but keep in mind this was not slapping parts together.You get into alot of compromises such as going with the larger comp xe274 with only 8.5 actual compression since you need more cam to make power with the limited lift of the stock rockers,but in this case the velocity of the small heads helps you out with bottom end performance.I also had a spot on tune but it just shows there are many ways to make power on the cheap and this goes with what Wilde is showing here.You can p.m. if you would like more info,I dont want to steer this thread off course anymore,thanks for the thread Wild.
 
Ok ..so i ported a lil more on them today. I did a lil short turn work up to the straight wall ...at 1st it seemed to pick up a few cfm on the lower/mid lift, but it led to turbulence and the flow dropping off at .550 with 192cfm...but nothing major at all, even rough cut still.

----CFM@LIFT----
.100--63.7
.200--127
.300--172
.400--185
.500--190
.550--192
.575--187

318 Head Porting 44-1.JPG


318 Head Porting 44-2.JPG
 
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After testing I initially decided to work the push rod wall at and beyond into the bowl..since the air seemed to be really moving there...but then looked at the bowl and decided it needed more work on the straight side...so i worked the straight wall at the bowl and up between that side of the guide some, as well as the far side of the bowl just a smidge. I did however lose 4 cfm @.400 lift...but there were more gains below and above to really call it a loss..
The push rod pinch imo is coming into the picture....so tomorrow i will go there and report.
Fresh 3+ angle wold help too of corse, but remember this is for the sake of the guy who would like to pull'em off , do some porting, and then bolt'em back on..so a new VJ is optional..lol..it could only add a few cfm at the least and actually equalize the flow range at mid lift.

The numbers after that
---cfm@lift----cfm gain over stock flow
.100--66---------------20+
.200--131--------------23+
.300--173.3------------16+
.400--181.4------------12+
.450--188--------------didnt check stock .450
.500--190--------------19+
.550--192--------------19+
.575--195.6------------20+

I also did an exhaust port that Ill flow tomorrow, I have pics of that as well that ill go ahead and post now for something to look at till tomorrow.

318 Head Porting 45-1.JPG


318 Head Porting 45-2.JPG


318 Head Porting 45-3.JPG


318 Head Porting 45-4.JPG


318 Head Porting 45-5.JPG


318 Head Porting 45-6.JPG


318 Head Porting 45-7.JPG
 
exhaust port progress, numbers come tomorrow..

u can completely rid the roof of the speed bumps like done below, then round the bowl and leave the slightest lil micro bell shape to the seat on the far side and blend the guide & bowl roof out to the window..then straight up off the seat and rolled a lil back at the top for the ssr.
These are just in the process and rough cut, not quite done yet.

318 Head Porting 46-1.JPG


318 Head Porting 46-2.JPG


318 Head Porting 46-3.JPG


318 Head Porting 46-4.JPG


318 Head Porting 46-5.JPG


318 Head Porting 46-6.JPG
 
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duster731 said:
Sorry double post but since I can't delete it ill ask a question ..

Lead69. So basically if I were to put 318 heads, air gap int, 650 pd, and a good cam on a 360 block it would be a 12 second motor? Just curious
Click to expand...

Yes, visit the drag racers forum and the tips thread on the 12 second zone and what others are doing to do it.
 
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