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Street 403C on the Dyno

D danieljonesMember
I was out of town on business but Dave McLain has the 403C for my white Pantera
on the dyno. The block is the 4 bolt main block out of my red Pantera. While
it had seen only 25K miles, it needed a slight clean up due to some surface
rust so we decided to go to a 4.005" bore using off-the-shelf Diamond 351C
stroker pistons. The parts list looks like:

Ford 351C block 4 bolt main block, 0.005" over (4.005" bore), not zero-decked
Diamond forged Cleveland stroker pistons (4.005" bore for 4" stroke and 6"
rods, 14.5 cc's dished, plasma moly rings)
403 cubic inch displacement (4.005" bore by 4" stroke)
SCAT 4340 steel forged 4" stroke SVO (Windsor design with Cleveland mains,
requires snout spacer) crankshaft
SCAT 4340 forged steel I-Beam rods (6" long with 7/16" ARP bolts)
Romac 351C SFI spec harmonic damper, zero balance
Clevite H-Series rod bearings (for SBC dimension rods)
Stroker kit internally balanced
Schiefer neutral balance aluminum flywheel
Crane link bar retrofit hydraulic roller lifters (p/n 36532-16)
Mallory Unilite vacuum advance distributor (small cap for Pantera firewall
and rear window clearance)
Crane steel distributor gear (p/n 52971-1 for 351C with 0.531" shaft dia.)
Pioneer brass freeze plug set (p/n 830005)
J.P. Performance double roller timing chain (German Iwis chain)
Ford Motorsport M-6005-A351 heavy duty chrome moly oil pump driveshaft
Blueprinted Melling M84A standard volume oil pump
Ultra Pro Machining hydraulic roller oil
Armondo Pantera gated and baffled road race oil pan
Ford Motorsport high port head gaskets for 351C block
Edelbrock aluminum 351C water pump (p/n 8844)
Trend custom length 0.080" wall push rods (for the taller roller lifters)
Fuel pump block off plate (dyno providing the fuel flow)
Bullet custom hydraulic roller cam (see specs below)
Competition Cams beehive springs (p/n 26095, 150 lbs @ 2", 375 lbs @ 1.25")
QFT SS-830 carb (claimed flow 900 CFM @ 1.5" Hg)
MagnaFlow single 2.5" inlet, dual 2.5" outlet mufflers, polished stainless
steel (p/n 14218, 5" thick, 8" wide, 14" case length, 20" overall)
ARP head bolt kit (with hardened washers)
Crane gold race aluminum 1.73:1 351C 7/16" stud mount roller rockers

I had some of the parts in my stash and Brent Lykins supplied the internally
balanced stroker kit while Alex Denysenko supplied the rest of the bits.
This engine will initially go into my white 1974 DeTomaso Pantera L but
will likely end up in my 1956 F100 project truck (whenever I get around
to it). The white Pantera is strictly a street car and is a nice weather
daily driver. The goal is similar to the 408C we did for Mike Drew's
Pantera (peak around 6000 RPM with excellent street manners and reasonable
fuel economy). Mike's engine made 526 HP and 500 ft-lbs through the dyno
mufflers and he reports 18 MPG tearing through the mountains at 80+ MPH so
we think it could do 20 MPG during a level terrain cruise). Anyway, that's
the benchmark to beat.

I designed the hydraulic roller cam using Dynomation and crossed it against
the Bullet lobe catalog. Specs are:

293/298 degrees duration @ 0.050" lift
238/242 degrees advertised duration
0.640"/0.574" lift (with 1.73:1 rocker ratio)
110 lobe separation angle
Bullet CRA type intake lobe HR293/370
Bullet CRS type exhaust lobe HR298/332

Type CRA which means a grind with a conventional nose (as opposed to a nose
designed for a lift-rule race class), a lobe shape good for RPM and/or high
lift rockers (applies to 351C's 1.73:1 rocker ratio) and asymmetrical
opening/closing (helps with valve bounce). CRS is the same but with a
symmetric lobe. The flow numbers used for the cam design were gathered
without a pipe extension which biases the design for more exhaust duration
than if they were flowed with a pipe (adds approximately 30 CFM). If I had
it to do over, I'd probably shorten the exhaust duration a bit.

We have several sets of Ford Motorsport A3/C3/C302/C302B high port aluminum
Cleveland heads available for testing, along with with matching intake
manifolds and exhaust headers. Some of the heads have stock chambers
(Cleveland quench chambers) while others have been clearanced for domed
pistons so the compression ratio will vary but should be in the 10:1 range.
We won't test them all but here is the head line up that we have to choose
from:

1. large port A3 (unported but smoothed, early exhaust bolt pattern)
2. large port A3 (some port work but not flow tested, late exhaust pattern)
3. E2ZM-6090-A3 Phase 1 1/2 (2.19/1.71, narrow C302 intake port, larger A3
oval exhaust, D shaped chambers, dated 11/15/83D and 11/14/83N)
4. E3ZM-6049-C3 (unported but smoothed, oval exhaust port)
5. E3ZM-6049-C302B (ported but small port, late flange, common height
bosses, ex-Alan Kulwicki, still need to flow bench test)
6. E3ZM-6049-C3 (2.15/1.65, ported, unshrouded, intermediate intake port,
D-shape exhaust port, short boss, late exhaust flange, currently has
Windsor coolant routing, dated 4/23/86N)
7. E3ZM-6049-C302B ported (larger intake ports, rectangular exhaust ports,
late flange, common height bosses)
8. E3ZM-6049-C302B ported tulip head exhaust valves, best flowing of all
the heads, on Fontana short block but not torqued down

For the large port A3 heads, the intakes available for testing include:

1. A331 Edelbrock low rise single plane (A3 port version of the Torker)
2. A331 Edelbrock low rise single plane (modified with plenum extensions)
3. Scott Cook low rise dual plane (looks like Ford Boss 351 intake, CHI 3V port)
4. CHI 3V single plane tall single plane (4150 flange version)

We can also run the smaller port C302B intakes on the A3 heads. For the
smaller port C3/C302/C302B ports, the intakes available for testing include:

1. Roush A331 unported
2. Roush B351 unported
3. Roush B351 ported (ex-Alan Kulwicki)
4. Edelbrock D351 unported

Headers available include:

1. Precision Proformance 4-into-1 shorties for 9.2" deck block with high port
heads in Pantera chassis, slotted to fit both early and late high port
flange patterns, fits either A3 or C3/C302/C302B heads (2" OD, 1 7/8" ID
primaries with lengths that vary from 12" to 20" long, collector ID is
2.39" and length is 6")

2. 180 degree Pantera headers for 9.2" deck block with C3/C302/C302B heads,
Mad Dog's old headers

3. Stainless steel full length tri-y's for small port late model flange only,
1 3/4" OD first pair, 2" OD second pair with 2.5" diameter collectors

4. Circle track high port headers, upper bolt holes elongated to fit both
early and late bolt patterns, stepped tubes with bolt-on 3 1/2" collectors,
3 1/2" diameter extensions

Mufflers are 2.5" single inlet/dual outlet Magnaflow mufflers and all dyno
runs will be through mufflers unless otherwise noted.

I went with internal balancing as I already had a neutral balance aluminum
flywheel (a NOS Scheifer unit I got cheap because it was Ford 300 truck
inline six part). Since we were internally balancing, we chose SCAT's
I-Beam rods over the heavier H-beam rods as the light rods require less
Mallory metal in the bob-weights. Diamond had an off-the-shelf piston for
the combo to round out the stroker kit.

The oil is a special blend for hydraulic rollers that reduces the leakage
rate and meant to be used with pre-load set to zero lash. Out-of-the-box,
the carburetor was really rich with poor idle and part throttle but ran fine
at wide open throttle. The QFT SS series carbs have replaceable idle feed
restrictions so Dave reduced them to cure the problem.

Ford Motorsport used to offer the M-6065-A351 head bolt kit (1/2" diameter
bolts that are 1" longer than production 351C bolts, with hardened washers)
for installing SVO high port aluminum heads on 351C iron blocks but they are
no longer available. I ordered what was supposed to ARP's equivalent kit
but only half of its bolts were the correct length so Dave sourced replacements
for the other bolts. I've since found an M-6065-A351 bolt kit.

Also obsolete is the FRPP snout spacer part number M-19009-A341C which
is required with 351 SVO crankshafts used in iron 351C blocks. Dave had
one he measured:

0.400" thick
1.830" OD
1.360" ID
45 degree chamfer about 0.125" wide on one end of the ID

and makes spares as he needs. They only need to be a slip fit. After
he made mine, I found several spares at a local machine shop.

The first set of heads tested are the unported but cleaned up A3's which were
mated to the Pantera shorty headers and an A331 intake manifold. Dave did
some work on the plenum and added runner extensions to the intake to try to
get it to tune to a lower rpm which appears to have worked. Dave's dyno is
known to be 4% to 5% conservative compared to the calibrated Engine Masters
dyno (verified on Dave's 351C and 460 based EMC entries). Adjusting for that,
the A3 and A331 top end made 560 HP @ 6300 RPM and 512 lbs-ft @ 4900 RPM
through the 2 1/2" single inlet/dual outlet Magnaflow mufflers. HP hung in
until 6500 RPM and then started to drop off and it liked approximately 36
degrees total timing and a 1 inch open spacer under the carburetor. Dave said
he's going to mess with the jetting a bit more and then switch to the Cook
dual plane intake manifold. Removing the mufflers was worth about 10 lbs-ft
and 5 horsepower so not too bad but could probably benefit from a cross-over.

A promising start, given that Dynomation predicts the smaller ported heads to be
better by 20 to 35 HP. Info on the first set of heads tested:

A3 Ford Motorsport High Port Heads minor clean up, 2.19 intake, 1.71" exhaust,
2.74 square inches minimum intake port area, 1.88 square inches minimum exhaust
port area, intake port 2.125" H by 1.725" wide (3.665 square inches), exhaust
port 1.65" H by 1.725" wide (2.27 square inches), tested on Dave McLain's
SuperFlow flow bench at 10" and converted to 28". Clayed intake radius but no
exhaust pipe. As with most of the Cleveland heads we've tested, they generate
little to no swirl motion.

Lift Int Exh
Inches CFM CFM
0.025 15.7 11.7
0.050 34.6 28.1
0.100 65.5 56.7
0.150 95.2 87.5
0.200 129.2 109.8
0.300 188.8 142.4
0.400 242.8 167.0
0.500 287.7 186.7
0.600 321.4 204.4
0.700 337.7 216.3

Note: Dave's bench tends to be conservative compared to others I've tested the
same heads on (by 20 CFM or so) on but gives good results in Dynomation. These
numbers are very similar to what CHI-3V and CHI-4V heads produced on Dave's
bench.

Some parts pictures:



The top end parts and Pantera headers we're currently testing:



Pantera oil pan:




and a couple of the block wire wheel stripped to bare metal:




Dan Jones
Original Post

Replies sorted oldest to newest

D danieljonesMember
> These are real nice Stainless steel full length tri-y's ...where did they come from ?

They came from Kirk Evans. I'm not sure who he got them from but they were
built for an engine that Gary Roys owned. Kelly Coffield bought that engine
which coincidentally is at Dave McLain's shop now. The headers didn't have
the second merge to make them a tri-y, instead dual pipes went into dual
mufflers per side. I purchased a set of stainless merges and 2" pipe to
mock up for the dyno. If they work well, I'll see if I can make them fit
the Pantera chassis.

Dan Jones
panteradougpanteradougMember
Your numbers are reinforcing to me why it is so difficult to find A3 heads. For all intents and purposes they look to me like the best bang for the buck.
Are those headers actually stainless or are they just coated?
The coaters are quoting a measurable flow increase for virtually all the product lines.
Eastern Connecticut Coatings, who did mine, said they could show dyno results for something like a 15% increase. 15% of what?
Can anyone verify that?
D danieljonesMember
> Are those headers actually stainless or are they just coated?

Ah, I see the confusion. The ones in the pictures above are from Precision Proformance
(Byars) and are 4-into-1, not tri-y. They are coated and are the headers we are
currently running on the A3 heads.

These are the stainless tri-y's (dusty but should shine up):





They will be used on the smaller exhaust port C3/C302/C302B heads only as the port
size at the flange (1 3/4" OD primaries) is too small for the large A3 exhaust ports.
The merge I'm using came from Verocious Motorsports (from Kelly's header building post)
and is designed to slip over two 2" OD pipes and has a 2.5" outlet (same as the inlet
to my Magnaflow mufflers):



It needs about 14" of dual 2" leading to it to make it a real tri-y. It originally
had two 2" pipes leading to dual mufflers per side. Kirk didn't think it would fit
the Pantera as originally fabricated. I still need to mock it up in the red Pantera.

Dan Jones
panteradougpanteradougMember
Ahhh. Interesting. I remember building a set. Got all depressed looking at them unpolished.
Discovered that with the new thermal coatings, stainless was no longer necessary. Plus the stuff is just nasty to work with for headers.
These will fit if you make a Susa pipe for them, i.e., Two 180 u-bends then into the muffler.
Incidentally Steve Wilkinson says his new Ansa look alike mufflers fix the HP loss of the originals. You should check in with him on that issue.
D danieljonesMember
Externally, the Edelbrock A331 looks like a Torker:



but has smaller A3 ports and no cross-over:



You can see how much smaller the A3 port is here:



That's a 4V gasket on top of an A3 port. What's not obvious is the A3 roof is higher
(obscured behind the gasket).

You can clearly see the evolution of the high port heads here:



On the left is an iron 4V modified with an aluminum high port exhaust port plate like
they ran in Pro Stock. You can see the lower edge of the original exhaust port (painted blue).
In the middle is an A3 port which is slightly higher with a more uniform round shape, instead
of the weird area changes of the iron 4V port. At the right is a ported C302B. The C302B
ports start out much smaller as you can see from this scan from an old Ford Motorsport
catalog showing a comparison of C302, B351 and A3 high port heads:



The same heads as above on the intake side:



and the chambers:



High ports share the quench 4V chamber design. The C302B head on the right has been
clearanced for a domed piston.

Dan Jones
D danieljonesMember
Last night Dave tested the Scott Cook dual plane intake. I forgot to snap
a picture before dropping it off at the dyno so I grabbed this one from
the Cleveland Wiki




Scott's intake manifold looks much like a Ford cast iron DOAE-9424-L dual
plane but is cast in aluminum, slightly taller (around 10 mm or a bit more
than 3/8") with smaller ports that are sized like a CHI 3V. Luckily the
intake was also designed to fit a 4V iron heads so also fits the A3 high
port heads. Like the over-the-counter version of the Boss 351 intake,
it has two oval holes in the carb flange instead of the four circular holes
of the iron Ford intake. The one tested is one of Scott's first generation
intakes and he has since redesigned it to work better on larger displacement
engines with good flowing heads. Given that it's the earlier design, both
Dave and I thought it might be out of its element on my 403C but it surprised
us. The dyno fuel log wouldn't clear without a spacer so it was run with
a couple of different 1" spacers, making the best HP with HVH 4 hole spacer
registering 569 HP @ 6350 RPM and 511 ft-lbs @ 4750 RPM. Switching to a
1" open spacer, increase peak torque to 514 ft-lbs @ 4700 RPM but HP wasn't
quite as good. Pop the mufflers off (or use the larger 3" inlet/outlet Magnaflows)
and it might make 575 HP with a street hydraulic roller.

Paint the A3 heads and Cook intake Ford blue and no one would know it's not a
stocker. In fact, that set up would fit under the hood of my 1966 Mustang
fastback but would require notching the shock towers for high port header
clearance. The 225/60/15 tires would not be happy :-)

Intakes to follow include a Roush B351 and CHI 3V single planes. On an earlier
test on the 351C dyno mule with CHI-3V heads, the very tall CHI intake picked up
20 HP over the low profile Cook dual plane. Will the trend continue?

Dan Jones
D danieljonesMember
> I seem to think that the A3 head exhaust ports flow significantly better with a 3" radius tube on it?

You may be recalling flowing with a 3" long straight pipe stub.
A head like an A3 will pick up 30 CFM on the exhaust with a pipe
stub versus a bare port. Most of the advertised and magazine
flow data you see will be with a pipe stub. However, the flow
bench data I've gathered on my high port heads has been with a
bare port. I think if I flowed them with a pipe stub and used
that data in Dynomation when I design a cam it will result in a
shorter exhaust duration.

Dan Jones
D danieljonesMember
> love to see the SVO stuff on the dyno!

That 1980's tech works really well.

> Are you planning on running either of the c302b 7, or 8 on your list?

I will run 7. I may not run 8. The springs it has on the intake side
might not have enough travel before coil bind.

> I've got an SVO based build I will post up so it doesn't derail this thread.

Post away.

> Look forward to seeing if you run the 180's as well.

Those should be interesting.

Dan Jones

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