head flow comparo - maybe of interest

head flow comparo - maybe of interest

Joined: September 5th, 2006, 1:33 am

June 11th, 2012, 11:33 pm #1



Maybe this is like the dead horse that continues to take a beating, but I had the last 3 sets of heads I used flowed to see what differences might crop up. Not exactly apples to apples, but I thought it interesting.

1st set is my original (DOZE-6090A, both cast on same day) '70 Boss 302 heads. Mild or "normal" Les Schmader porting job. For a 310CI Boss, so Les said he did not go as far as he could have on the exhaust. 2.125 Ti Int and 1.71 SS Exh valves. Lots of numbers floating around about how well these flow in stock form.
Lift INT EXH
.200 158 105
.300 220 154
.400 264 189
.500 295 205
.600 320 210
.700 335 212

2nd set is a pair of PC 3061 351C versions. Bought these years ago by mistake, before I knew they were Chicom. Les Schmader did another "normal" porting job on these. He said he liked the castings, as far as their symmetry and lack of porosity. He did take note of the badly sunken seats, as received. 2.19 SS Int & 1.71 SS Exh valves. These originally had max flow numbers of about 270 intake and 175 (IIRC) exhaust.
.200 127 119
.300 180 134
.400 227 166
.500 280 195
.600 312 210
.700 333 220

The 3rd and last ones I had checked are some of the older (2005 or 2006 version) AFD 4Vs. I got these from someone else. They have not been ported, although the PO did grind off some flash, and did a rather unusual looking port/gasket match on the intake and exhaust.
I imagine with the same porting as the other two sets had, these might be "better", but they're going on another small cube engine, so they're more than enough as is. 2.19 SS Int 1.655 SS Exh.
.200 122 104
.300 184 134
.400 248 162
.500 298 188
.600 311 205
.700 312 220
.800 316 227

The B302s give away nothing for flow on the intake side, but I sure wish I had velocity numbers for all 3 sets. People more expert than I can draw worthwhile conclusions, I reckon, but I was sure happy with the low lift flow on the B302s. Is it possible that those numbers are that "good" simply because of the larger volume of the port(s)?



A Visigoth explains the sack of Rome: We wanted art, literature...culture! We're sorry we broke some stuff.
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Joined: February 13th, 2006, 4:59 am

June 12th, 2012, 3:17 am #2

I'm impressed by the cast iron flow no.s for sure. I thought the afd heads would have been better on intake but still impressive for sure. Ford new there stuff in the old days !
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Joined: October 1st, 2004, 8:05 pm

June 12th, 2012, 10:33 am #3



Maybe this is like the dead horse that continues to take a beating, but I had the last 3 sets of heads I used flowed to see what differences might crop up. Not exactly apples to apples, but I thought it interesting.

1st set is my original (DOZE-6090A, both cast on same day) '70 Boss 302 heads. Mild or "normal" Les Schmader porting job. For a 310CI Boss, so Les said he did not go as far as he could have on the exhaust. 2.125 Ti Int and 1.71 SS Exh valves. Lots of numbers floating around about how well these flow in stock form.
Lift INT EXH
.200 158 105
.300 220 154
.400 264 189
.500 295 205
.600 320 210
.700 335 212

2nd set is a pair of PC 3061 351C versions. Bought these years ago by mistake, before I knew they were Chicom. Les Schmader did another "normal" porting job on these. He said he liked the castings, as far as their symmetry and lack of porosity. He did take note of the badly sunken seats, as received. 2.19 SS Int & 1.71 SS Exh valves. These originally had max flow numbers of about 270 intake and 175 (IIRC) exhaust.
.200 127 119
.300 180 134
.400 227 166
.500 280 195
.600 312 210
.700 333 220

The 3rd and last ones I had checked are some of the older (2005 or 2006 version) AFD 4Vs. I got these from someone else. They have not been ported, although the PO did grind off some flash, and did a rather unusual looking port/gasket match on the intake and exhaust.
I imagine with the same porting as the other two sets had, these might be "better", but they're going on another small cube engine, so they're more than enough as is. 2.19 SS Int 1.655 SS Exh.
.200 122 104
.300 184 134
.400 248 162
.500 298 188
.600 311 205
.700 312 220
.800 316 227

The B302s give away nothing for flow on the intake side, but I sure wish I had velocity numbers for all 3 sets. People more expert than I can draw worthwhile conclusions, I reckon, but I was sure happy with the low lift flow on the B302s. Is it possible that those numbers are that "good" simply because of the larger volume of the port(s)?



A Visigoth explains the sack of Rome: We wanted art, literature...culture! We're sorry we broke some stuff.
James

Remember, although the 4V intake port entrance is admittedly large, it shrinks in size further into the port. The "average cross-sectional area" is not unreasonable at all. If the intake ports in the other two heads are intersecting the valve pocket at the same angle as the 4V intake port, if the geometry is the same, and the ports flow approximately the same, do you think the average cross-sectional areas will be that different? The 4V intake port is a wonderfully designed port. Its the exhaust port that was muffed up.

What you want to compare is the average cross-sectional area of the ports ... not the gas velocity. That gas velocity thing is just the garbage you've been fed clouding your mind. Advertising hype. Respectfully. I don't mean that in an unkind way. Knowing the average cross-sectional area would be enlightening for you.

A port can be too small, just as easily as it can be too large. Most often ports ARE too small. That's why the aftermarket can make such drastic improvements in the performance of most motors. But the aftermarket has a hard time doing better than a set of ported 4V heads, because the ports are't too small. But the ports aren't too large either ... there are no documents validating that velocity is too slow in the 4V port, there are no documented reversion problems or documented problems with the fuel falling out of suspension. Just heresay, anecdote and theoretical arguments.

Did you know if the fuel and air mixture is traveling too fast in the runner, when it turns to enter the valve pocket the fuel will be thrown out of suspension by centrifugal force?

We don't drive flow benches, we don't drive dynos. The stop watch is the best way to meter performance, but the "power characteristic" or "power band" can only be described by somebody who has driven the vehicle. Another member just the other day was bragging about the low rpm torque of his 351 cubic inch motor with 4V heads. I don't think he was hallucinating. But no matter how many people testify like that, people have a hard time letting go of the belief system that says the ports are too big. In 40 years that has never been my experience.



-G
____________________________________________________________



Kick Him Often Enough ... And Even A Dog Will Leave
To Find A New Home Where He Isn't Kicked
Last edited by gpence on June 14th, 2012, 7:07 pm, edited 1 time in total.
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Joined: September 5th, 2006, 1:33 am

June 12th, 2012, 7:44 pm #4



Just sticking it out there to see if I can learn something more, George. If I am incapable of learning anymore, I might as well be dead.
According to my rough CC measurements, the B302s are right near 247CC volume, the PCs 221 and the AFDs 235. That doesn't show me anything like the Ford ports are "too big", as in the flow stalling out. I would have liked to seen a velocity list, though, as I have seen the sort of random drops in power on dyno tests that others on the forum have mentioned. I don't even know if those data would be correlatable(?). The outfit that tested the AFDs for me did list valve velocity, but not port velocity. Whatever, if anything, valve velocity indicates.
The B302 heads have been with me since 1975, and I had never been tempted to modify them in any way before. I did think some other technological improvements (cams and so on) might make it worthwhile. For the PC heads, I didn't give a s###, since they didn't really flow s### as received, but wondered if some of the claims of potential improvement (like those of Dr. J) held water. With the AFDs, it was to see from my point of view if buying expensive aftermarket heads was really any better than getting a reasonable port job on the old iron beauties, for anything but weight reduction.
Ah well...bottom line, I bet I will be more than happy with how the iron heads perform, as I have been in the past.

A Visigoth explains the sack of Rome: We wanted art, literature...culture! We're sorry we broke some stuff.
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Joined: February 13th, 2006, 4:59 am

June 12th, 2012, 9:00 pm #5

James it would be interesting to see the difference on the dyno as well as 1/4 mile times? Now that you have the cc values and flow no.s it would be cool to see what it all equates to? But we are not all made of money and spare time I guess! Maybe Dan has some dyno nos on these same heads?
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Joined: February 17th, 2004, 11:02 pm

June 12th, 2012, 10:29 pm #6



Maybe this is like the dead horse that continues to take a beating, but I had the last 3 sets of heads I used flowed to see what differences might crop up. Not exactly apples to apples, but I thought it interesting.

1st set is my original (DOZE-6090A, both cast on same day) '70 Boss 302 heads. Mild or "normal" Les Schmader porting job. For a 310CI Boss, so Les said he did not go as far as he could have on the exhaust. 2.125 Ti Int and 1.71 SS Exh valves. Lots of numbers floating around about how well these flow in stock form.
Lift INT EXH
.200 158 105
.300 220 154
.400 264 189
.500 295 205
.600 320 210
.700 335 212

2nd set is a pair of PC 3061 351C versions. Bought these years ago by mistake, before I knew they were Chicom. Les Schmader did another "normal" porting job on these. He said he liked the castings, as far as their symmetry and lack of porosity. He did take note of the badly sunken seats, as received. 2.19 SS Int & 1.71 SS Exh valves. These originally had max flow numbers of about 270 intake and 175 (IIRC) exhaust.
.200 127 119
.300 180 134
.400 227 166
.500 280 195
.600 312 210
.700 333 220

The 3rd and last ones I had checked are some of the older (2005 or 2006 version) AFD 4Vs. I got these from someone else. They have not been ported, although the PO did grind off some flash, and did a rather unusual looking port/gasket match on the intake and exhaust.
I imagine with the same porting as the other two sets had, these might be "better", but they're going on another small cube engine, so they're more than enough as is. 2.19 SS Int 1.655 SS Exh.
.200 122 104
.300 184 134
.400 248 162
.500 298 188
.600 311 205
.700 312 220
.800 316 227

The B302s give away nothing for flow on the intake side, but I sure wish I had velocity numbers for all 3 sets. People more expert than I can draw worthwhile conclusions, I reckon, but I was sure happy with the low lift flow on the B302s. Is it possible that those numbers are that "good" simply because of the larger volume of the port(s)?



A Visigoth explains the sack of Rome: We wanted art, literature...culture! We're sorry we broke some stuff.
> 1st set is my original (DOZE-6090A, both cast on same day) '70 Boss 302 heads.
> Mild or "normal" Les Schmader porting job.

The numbers Les got from those are very similar to what we got from 351C-4V
closed chamber heads with short side radius work.

> 2nd set is a pair of PC 3061 351C versions.
> Les Schmader did another "normal" porting job on these.

Les made a huge improvement over the out-of-the-box Pro Comps.

> He did take note of the badly sunken seats, as received.

I've seen some other Pro Comp ported numbers but they resorted to larger
valves to fix the sunken seats which might look good on the flow bench but
might not work so well on anything with 4.030" bore (due to shrouding).

> These originally had max flow numbers of about 270 intake and 175 (IIRC)
> exhaust.

That's consistent with what the ones we tested flowed:

Pro Comp 1/12/2009 (as used on the dyno project 351C)
Lift Intake Exhaust I/E
(in) CFM CFM
0.025 12.4 10.8 87.3
0.050 23.4 26.8 114.5
0.100 31.6 53.0 168.0
0.150 45.1 64.3 142.7
0.200 68.3 85.7 125.5
0.250 97.5 109.1 111.8
0.300 129.6 123.6 95.3
0.350 160.1 139.1 86.9
0.400 185.7 151.6 81.6
0.450 213.4 162.8 76.3
0.500 238.2 169.2 71.0
0.550 261.1 177.1 67.8
0.600 277.9 184.6 66.4
0.650 288.8 189.0 65.4

Did Les flow them at low valve lifts? Below 0.25" lift, our Pro Comps
had exhaust ports that flowed better then the intake. Really bad.

> I was sure happy with the low lift flow on the B302s. Is it possible that
> those numbers are that "good" simply because of the larger volume of the
> port(s)?

The low lift flow is good primarily due to the size of the valve and the cant
angle. Of course, raw flow is only one component of good cylinder head design
and performance. Velocity, detonation resistance, swirl, tumble, etc. all
matter.

Dan Jones
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Joined: February 17th, 2004, 11:02 pm

June 12th, 2012, 10:31 pm #7

James

Remember, although the 4V intake port entrance is admittedly large, it shrinks in size further into the port. The "average cross-sectional area" is not unreasonable at all. If the intake ports in the other two heads are intersecting the valve pocket at the same angle as the 4V intake port, if the geometry is the same, and the ports flow approximately the same, do you think the average cross-sectional areas will be that different? The 4V intake port is a wonderfully designed port. Its the exhaust port that was muffed up.

What you want to compare is the average cross-sectional area of the ports ... not the gas velocity. That gas velocity thing is just the garbage you've been fed clouding your mind. Advertising hype. Respectfully. I don't mean that in an unkind way. Knowing the average cross-sectional area would be enlightening for you.

A port can be too small, just as easily as it can be too large. Most often ports ARE too small. That's why the aftermarket can make such drastic improvements in the performance of most motors. But the aftermarket has a hard time doing better than a set of ported 4V heads, because the ports are't too small. But the ports aren't too large either ... there are no documents validating that velocity is too slow in the 4V port, there are no documented reversion problems or documented problems with the fuel falling out of suspension. Just heresay, anecdote and theoretical arguments.

Did you know if the fuel and air mixture is traveling too fast in the runner, when it turns to enter the valve pocket the fuel will be thrown out of suspension by centrifugal force?

We don't drive flow benches, we don't drive dynos. The stop watch is the best way to meter performance, but the "power characteristic" or "power band" can only be described by somebody who has driven the vehicle. Another member just the other day was bragging about the low rpm torque of his 351 cubic inch motor with 4V heads. I don't think he was hallucinating. But no matter how many people testify like that, people have a hard time letting go of the belief system that says the ports are too big. In 40 years that has never been my experience.



-G
____________________________________________________________



Kick Him Often Enough ... And Even A Dog Will Leave
To Find A New Home Where He Isn't Kicked
> The 4V intake port is a wonderfully designed port.

for the late 1960's.

> Its the exhaust port that was muffed up.

Oddly, the 2V exhaust port flows close to what a 4V port does with better
velocity and still fits within the narrow shock towers of the old Mustangs
and Cougars.

> What you want to compare is the average cross-sectional area of the ports

Average cross-sectional area of the ports is next to useless. Take a limiting
case. If you had a one square foot maximum area and a zero minimum area, the
mean would be one half square foot but it would flow zero. A huge average
cross sectional area that flows nothing. A more useful value is the minimum
cross sectional area since that determines the maximum port velocity. Taper
angle is also of some use.

> not the gas velocity. That gas velocity thing is just the garbage you've been
> fed clouding your mind. Advertising hype.

It's not hype, it's engineering. Volumetric efficiency increases with
increasing port velocity up to around 0.6 Mach or so. Low port velocities
are more susceptible to reversion. Momentum is the product of mass and
velocity. If the velocity is low, the momentum is low and may not be able
to overcome the rise in pressure that occurs when the intake valve closes
which allows reversion flow (from the cylinder back into the intake tract).
Reversion is very bad not just because the intake charge is diluted but also
for thermodynamic reasons. You want the intake flow to be cold and dense but
the exhaust flow is quite the opposite. A low air speed also implies a weak
pressure wave action which means weak resonant tuning. What you want is high
flow rates with relatively high port speeds (0.5 to 0.6 Mach in your working
range). Understand that energy (1/2*mass*velocity*velocity) in a port is
directly proportional to mass but is proportional to the square of velocity.
If the port is only 10% too large, you can lose more than 20% port energy.

> A port can be too small, just as easily as it can be too large.

True. See:http://www.dartheads.com/tech-articles/port-volume

> Most often ports ARE too small. That's why the aftermarket can make such
> drastic improvements in the performance of most motors.

The biggest factor is the increased flow rate of the cylinder heads.
A large port that flows little won't make much power. Shape and size go
hand-in-hand in determining the flow rate.

> But the ports aren't too large either ...

Then why did Roush and others stuff the 4V ports? Why did Ford make each
successive version of the high ports smaller (C302B heads are smaller
than B351 heads which are smaller than the A3's which are smaller than 4V's.
That the 4V was overly large for even most racing uses was realized early on.
I've got a book from the 1970's showing the Boss 302 head being tested on a
flow bench. The ports are filled with clay trying reduce the cross-sectional
area while maintaining flow. If there was no benefit to increasing velocity,
why would they bother? Even Ford's testing during the Boss 302 Trans Am
program revealed the smaller port Gurney-Weslake heads worked better on the
Boss 302.

> We don't drive flow benches, we don't drive dynos.

But every top team knows they must use both if they stand a chance of winning
a race. And every OEM uses both to develop their cylinder heads. They are
both useful tools.

> there are no documents validating that velocity is too slow in the 4V port,
> there are no documented reversion problems or documented problems with the
> fuel falling out of suspension.

Do you need your documents carved in stone?

> Another member just the other day was bragging about the low rpm torque of
> his 351 cubic inch motor with 4V heads.

"Just heresay, anecdote and theoretical arguments." For someone decrying
anecdotal evidence, you sure use it a lot.

> In 40 years that has never been my experience.

Not everyone's engine development ended in the 1970's.

Dan Jones
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Joined: October 1st, 2004, 8:05 pm

June 13th, 2012, 12:11 am #8

And please stop critiquing the replies of others

Everyone is entitled to his or her opinion.

If I were to fairly defend my position, or even reply to your critique, I would be rudely leading this thread off-topic, which is disrespectful of the OP. I've presented my recollections of the Cleveland scene in the 1970s elsewhere, I was involved with these motors back then.

Besides, this is not a debate forum. I'm not going to change your mind, that's why I don't try. And you shall never change mine either. So how about showing me the same courtesy I show you? I would like to be able to present my truth without you hounding me, over, and over, and over and over. I got the first memo for gosh sake! So did everyone else! Life is too short for this nonsense, there's too many bottles of tequila waiting to be drank, too many grandchildren to bounce, to many pretty girls to admire.

-G
____________________________________________________________



Kick Him Often Enough ... And Even A Dog Will Leave
To Find A New Home Where He Isn't Kicked
Last edited by gpence on June 14th, 2012, 7:08 pm, edited 1 time in total.
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Joined: February 7th, 2007, 1:05 am

June 13th, 2012, 3:05 am #9



Maybe this is like the dead horse that continues to take a beating, but I had the last 3 sets of heads I used flowed to see what differences might crop up. Not exactly apples to apples, but I thought it interesting.

1st set is my original (DOZE-6090A, both cast on same day) '70 Boss 302 heads. Mild or "normal" Les Schmader porting job. For a 310CI Boss, so Les said he did not go as far as he could have on the exhaust. 2.125 Ti Int and 1.71 SS Exh valves. Lots of numbers floating around about how well these flow in stock form.
Lift INT EXH
.200 158 105
.300 220 154
.400 264 189
.500 295 205
.600 320 210
.700 335 212

2nd set is a pair of PC 3061 351C versions. Bought these years ago by mistake, before I knew they were Chicom. Les Schmader did another "normal" porting job on these. He said he liked the castings, as far as their symmetry and lack of porosity. He did take note of the badly sunken seats, as received. 2.19 SS Int & 1.71 SS Exh valves. These originally had max flow numbers of about 270 intake and 175 (IIRC) exhaust.
.200 127 119
.300 180 134
.400 227 166
.500 280 195
.600 312 210
.700 333 220

The 3rd and last ones I had checked are some of the older (2005 or 2006 version) AFD 4Vs. I got these from someone else. They have not been ported, although the PO did grind off some flash, and did a rather unusual looking port/gasket match on the intake and exhaust.
I imagine with the same porting as the other two sets had, these might be "better", but they're going on another small cube engine, so they're more than enough as is. 2.19 SS Int 1.655 SS Exh.
.200 122 104
.300 184 134
.400 248 162
.500 298 188
.600 311 205
.700 312 220
.800 316 227

The B302s give away nothing for flow on the intake side, but I sure wish I had velocity numbers for all 3 sets. People more expert than I can draw worthwhile conclusions, I reckon, but I was sure happy with the low lift flow on the B302s. Is it possible that those numbers are that "good" simply because of the larger volume of the port(s)?



A Visigoth explains the sack of Rome: We wanted art, literature...culture! We're sorry we broke some stuff.
40 years experience porting cylinder heads and intake manifolds, and I take exception to one statement made by one of the posts. Velocity is critical if you want an engine to be responsive at low speeds, and velocity is important for total cylinder filling. Any time the volumetric efficiency exceeds 100% it will need velocity as well as shape, and size optimized. I have had engines produce as much as 123-124% VE, and produce near 2.1 hp/ci with heads that were mapped on the flow bench for velocity and flow. Boss 302 heads are neat heads for their time, but there are much better sizes that are smaller that flow much more air than a well worked/ported Boss iron head. The C302B head routinely flows 380/270 with 2.19/1.71 @.750" when ported properly. I recently ported 2 sets of the new aluminum Mummert Y-block heads that flow 280+cfm through a 1.940 intake valve, and 210 cfm through a 1.540 exhaust valve without a pipe. Was velocity important? Definitely. On the dyno, the heads helped make over 504 hp, on 352 cubic inches of Y-block. Joe-JDC.
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Joined: April 12th, 2004, 6:14 pm

June 13th, 2012, 3:51 am #10



Maybe this is like the dead horse that continues to take a beating, but I had the last 3 sets of heads I used flowed to see what differences might crop up. Not exactly apples to apples, but I thought it interesting.

1st set is my original (DOZE-6090A, both cast on same day) '70 Boss 302 heads. Mild or "normal" Les Schmader porting job. For a 310CI Boss, so Les said he did not go as far as he could have on the exhaust. 2.125 Ti Int and 1.71 SS Exh valves. Lots of numbers floating around about how well these flow in stock form.
Lift INT EXH
.200 158 105
.300 220 154
.400 264 189
.500 295 205
.600 320 210
.700 335 212

2nd set is a pair of PC 3061 351C versions. Bought these years ago by mistake, before I knew they were Chicom. Les Schmader did another "normal" porting job on these. He said he liked the castings, as far as their symmetry and lack of porosity. He did take note of the badly sunken seats, as received. 2.19 SS Int & 1.71 SS Exh valves. These originally had max flow numbers of about 270 intake and 175 (IIRC) exhaust.
.200 127 119
.300 180 134
.400 227 166
.500 280 195
.600 312 210
.700 333 220

The 3rd and last ones I had checked are some of the older (2005 or 2006 version) AFD 4Vs. I got these from someone else. They have not been ported, although the PO did grind off some flash, and did a rather unusual looking port/gasket match on the intake and exhaust.
I imagine with the same porting as the other two sets had, these might be "better", but they're going on another small cube engine, so they're more than enough as is. 2.19 SS Int 1.655 SS Exh.
.200 122 104
.300 184 134
.400 248 162
.500 298 188
.600 311 205
.700 312 220
.800 316 227

The B302s give away nothing for flow on the intake side, but I sure wish I had velocity numbers for all 3 sets. People more expert than I can draw worthwhile conclusions, I reckon, but I was sure happy with the low lift flow on the B302s. Is it possible that those numbers are that "good" simply because of the larger volume of the port(s)?



A Visigoth explains the sack of Rome: We wanted art, literature...culture! We're sorry we broke some stuff.
DOES ANYBODY ELSE GET GOOSEBUMPS WHEN DAN LAYS OUT THE FACTS? Love it.

Dan for the sake of those in here who are just getting involved in engine building please continue your "critiques". As an engineer I like to see measureable data from reliable, repeatable research. In other words, I like dynos, flow benches, and quarter mile results. The seat of my pants tends to tell me what I want it to based on whatever I just changed.

Engine building is an engineering based science, not something you feel in the seat of your pants. Fluids Fluid dynamics is a science. Fluids will perform in a predictable manner irregardless of who cast the iron around it. Modern engineers have access to software that wasn't available to even the highest levels of engineering in the late 60s. I use software everyday that could be used by a halfass engineer like myself to produce a head design in just a couple work days.

Having a personal love affair with 1970 era Ford cast iron is fine, but it doesn't change the fact that The last 40 years of research have yielded positive results in every aspect of cylinder head design. Personally I run cast iron heads in my vehicles because I'm cheap and have a bunch of the stuff laying around. Not because I think jesus christ himself came back and layed his hands on 351C casting cores.

I personally appreciate your comments Dan. Keep them comming.

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