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Canfield Head Porting (Updated)

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Discussion starter · #21 ·
Originally posted by One-Bad-70:
[qoute]The bore fixture no doubt makes a big difference on flow numbers. A 4.50" fixture can be worth 25-30 cfm (depending on head), over a 4.25" fixture.
Click to expand...
Yep, it sure can, I'll bet if their measured
on a 4.125 those numbers will drop.

Question, how much ( if you don't mind me
asking ) did those Canfield heads cost you.

One thing to remember thro, it's the port
shape and cross section that really matters,
not saying flow isn't important, cuz it is.
I'd be interested in knowing what the port
volume is. [/QUOTE]

Thanks for choosing my post for your first ever reply after just registering on the site :rolleyes: Can you say troll?
 
#22 ·
It's a very interesting post, I'm thinking
of going with a set of Cantfield, a friend
just made 730HP on pump gas with a 540 CID
and went 10 flat off the trialer, I'm impressed.
It's a 70 Chevelle all steel except the hood.

He did his own heads, claims all he did was
clean them up, but he's also got big cubes.
 
#24 ·
Ken, my thought on the bore fixture size vs the flow number differences seen.

I'm thinking that maybe your head porters flow bench is a bit more conservative than your buddies was. This might account for very similar before flow numbers, yet the head porters bench was using a larger bore fixture diameter.

Just like dynos, no two flow benches will flow exactly alike, as you already mentioned.

Seems logical to me, so lets just let it go at that :D .

I'm fully convinced that a larger bore fixture will increase flow numbers my a measurable amount mainly due to valve unshrouding. Why the manufactures of heads advertise the larger bore diameter bore fixture flow numbers? Two reasons IMO...one is Marketing plain and simple...higher flow numbers sell heads. The second reason to a lesser extent may be that larger bore 500+ ci engines are more common place now than in the past.
 
#25 ·
Kjett, I have info of a back to back comparo of AFR 315 heads done on a 4.25 and 4.50 bore fixture. It was 282@.400, 348@.600 with the 4.25" and 315@.400, 375@.600 with the 4.5".

The 4.125" bore fixture your friend used was basically a big bore small block fixture, since no BBC has a 4.125" bore. Thats why your original head flows seemed "low". You mentioned that the heads measured 330 cfm, but your figures show 316 cfm max, so I assume Champion baselined it on the 4.40" fixture and got 330 @ .700. If thats so, then you got nearly an 11% increase at .700, and probably even more at lower lift. Impressive for staying with what sounds like a relatively small port volume.

10secBu is 100% right. Big bore big blocks are very common now, so a 4.50-4.60 bore fixture is usually used. And the big flow numbers make a good selling pitch.
 
#26 ·
Here you go Mikey right from AFR site

All flow figures taken in this test were recorded using a 4.250 bore fixture. Current chamber designs and valve sizes used today (typically 2.250 - 2.350 for BBC intake valves) would show better results being tested on the larger 4.500 bore fixture. (Primarily due to unshrouding the valve with the larger bore size.) With so many production GM blocks, as well as the aftermarket, starting at 4.500 inches in bore size, we feel this is much more representative of the current trend in Big Block Chevy engine building. All published flow figures from AFR were obtained using a 4.500 bore fixture. However, the fact that all the information obtained at Westech was recorded using the same bore size (4.250), the same flowbench, the same operator, etc., this still proves to be a valid test and comparison, eliminating many variables that could potentially exist evaluating and comparing flow data.



The following information was recorded the same day at Westech, flowing the exact same AFR 315cc intake port, simply swapping test fixtures to the larger 4.500. These flow figures are almost identical to the published figures from AFR. They are
 
Discussion starter · #27 ·
Originally posted by -SS454-:
Kjett, I have info of a back to back comparo of AFR 315 heads done on a 4.25 and 4.50 bore fixture. It was 282@.400, 348@.600 with the 4.25" and 315@.400, 375@.600 with the 4.5".

The 4.125" bore fixture your friend used was basically a big bore small block fixture, since no BBC has a 4.125" bore. Thats why your original head flows seemed "low". You mentioned that the heads measured 330 cfm, but your figures show 316 cfm max, so I assume Champion baselined it on the 4.40" fixture and got 330 @ .700. If thats so, then you got nearly an 11% increase at .700, and probably even more at lower lift. Impressive for staying with what sounds like a relatively small port volume.

10secBu is 100% right. Big bore big blocks are very common now, so a 4.50-4.60 bore fixture is usually used. And the big flow numbers make a good selling pitch.
Click to expand...
I'm not doubting that the bore fixture makes a difference, just when and how much of a difference. Here's a link to the flow numbers (posted a originally a couple weeks ago) that I myself recorded for my heads before they were sent to Champion using an SF600 flow bench at my friends shop:

http://bellsouthpwp.net/k/_/k_jett/Images/Canfield/flownum.mht

As you can see max flow was 329.85 on several cylinders, not sure which figures you're referring to. Champion measured max flow at .800 lift same as we did. The only reason I only provided the new numbers through .700 lift is because that's all I asked them to focus on. My new cam has a gross lift of .726, which nets out to about .685 with .25 lash and valve train deflection. So back to my original point, I don't see where in this case the bore fixture size made that much of a difference. I'm certainly no flow bench expert, but I did spend about 10 hours using one a couple weeks ago. Wouldn't you think that if you move the head such that the intake valve is closer towards the center of the bore fixture that you have unshrouded the valve? How much do you think this would affect the readings? I already have a pretty good idea as I tried it myself ;) Try experimenting for yourself the next time you have access to a flow bench. You might be surprised what you find.

I'm sure every head responds differently, but I didn't see evidence that supports this theory with my heads. BTW, agree 100% on the marketing numbers
Image
 
#28 ·
Oh, I'm gonna weigh in. When I was flowing a lot of heads a couple of winters ago, I would be sure to place the head on the fixture in the same way every time, to eliminate variables, because shrouding is a big deal. We have only to think about good port/bad port in a BBC, and the huge flow differences we see there because the incoming charge on every other cylinder slams into the cylinder wall to a greater degree. As to the improvement with epoxying: you know, it makes sense because the pro stock boys seem to be downsizing and making more power, no? It's all about efficiency.
 
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#29 ·
kjett, here's how it goes, piston speed determends cross section size, you need X
amount cross section for a particular rpm range
and from what you explained", your head porter saying, the ports where to lazy. So he had to fill it in with epoxy, what he's talking about is velocity, if the ports to big there won't be
enough velocity to fill the cylinder bore. at
rpm range your looking for,that's very important. That a lone will increase flow numbers. Sounds like
to me he really knows what he's doing, and you
got your moneys worth. As I said before port shape
and cross section are most important.

Sure flowing with a bigger bore fixture will
produce more flow, my guess about 8 to 10 cfm
more, not really a big deal, when you consider
whether or not it will fill the cylinder.
 
#30 ·
The figures i was refering to were the ones you posted, that didnt go up to .800" lift, so I couldnt see the 330 cfm. I looked at the flow numbers, and I'm almost certain those advertised numbers by Canfield were on a 4.5" fixture, if not a 4.60". Compare those to the new mid range flow numbers, and its easy to see the gains. Ultimately they are just numbers, and the true test is when u get it to the track. Wolfplace would be a good person to talk to about flowbenching, as he has quite a bit of experience flowing heads with different fixtures.
 
#31 ·
Hi Kjett, This flow thing is quite an interesting subject. Increasing the flow while decreasing the size of the port should provide a few tenths improvement. My son had a 13-1 (482) in his Chevelle and put a set of 335 CNC Darts in place of the previous square port Chevy iron heads. This reduced the weight by 65 pounds or so and the car picked up about 3 1/2 tenths. I think you will see low 10s @ about 130-132 MPH with your changes. There is a comparison flow chart on the Chevy Hi Performance site. The AFRs picked up bigtime in the midrange flow numbers using a 4.5 bore fixture vs. the 4.25 one according to Westech. On the only head i've had checked on a Superflow 600 the exhaust didn't come up to expectations and the intake was a little low in the mid lift numbers. We are going to try this head anyway on a new 598" motor and see what happens. I'll post it's results no matter what, good or bad. Darin Morgan said flow doesn't mean much anyways; go figure. You might read the new article at the back of the National Dragster ( Dec.10, 2004 issue 46) page 154 written by David Reher. Some insite as to why the Pro Stock Cars continue to go faster with mostly the same parts.
 
Discussion starter · #32 ·
OK. Thanks for all the responses everyone. Like has been said, at the end of the day these are just numbers. The real test will be at the track and that won't happen for another couple months. I'll still post some pics of the heads when I get them back. I'm interested to see how the port was reshaped.
 
#33 ·
Let me guess,,,raised floor,raised roof,and more radiused port,large oval or roval...My axles,c clip eliminators and rear end support cover are here today,and motor is supposed to be done today. The first track around here opens the first weekend in Feb. weather permitting and I plan on being there
Image
 
#35 ·
Harold...MoKan usually gets one TNT in Feb. then its March before the weather moderates. I think I've made TNT at Mokan the first weekend of Feb. the last two years and the weather was near 70,then old man winter reared his ugly head again :(
 
#36 ·
Interesting observation Robert. I imagined the ports would be more rectanguar, however; with the width of the port reduced. I've always imagined air's momenteum forcing itself alongside the side of the port and not on the floor as the piston delta pressure sucking air through the carb I felt the bias of the carb to the intake valve. Am I making sense? Looking at a of older set of rec port heads it gives the impression that the floor of the port is shaped as an airplane wing to suck air from the start of the tract to the low pressure short turn radius. I got the idea from the newer LS1 heads that have over a 200cc intake track and look like recangular slots than ovals. Since I've seen the LS1 heads I've always looked at a intake port sideways.
 
Discussion starter · #37 ·
Several of you had inquired about the port volume and runner shape after the port job. The port volume in the big runner is 300cc. The port shape is still rectangle
Image
 
#38 ·
kjett said:
======
lift original New
.200 158.3 186.5
.300 222.9 260.7
.400 272.7 312.7
.500 299.0 347.6
.600 312.2 357.2
.700 316.6 366

Exhaust
=======
lift original New
.200 134.3 143
.300 179.2 199.2
.400 194.9 246
.500 235.8 275.6
.600 251.6 292.5
.700 264.1 299
Click to expand...

MY flows for same heads.

Orginal
0.050 48 24
0.100 126 50
0.200 159 96
0.300 245 134
0.400 274 167
0.500 302 227
0.600 342 233
0.700 359 245
0.800 380 265


Ported
0.050 50 24
0.100 80 48
0.200 159 108
0.300 250 157
0.400 297 186
0.500 338 223
0.600 362 239
0.700 383 254
0.800 400 291

28IN/HG With 4.500 bore 2.25/1.88 valves. Chamber/port job, no expoxi
 
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