Questions and Answers on the Ford 351
by Dan Jones
Mad Dog Antenucci wrote: (From the Detomaso Email List)
Listen Slackers,
There are two rules you need to remember
Rule #1 Dan Jones is always right.
Rule #2 If in doubt refer to Rule #1
I could write a Mikey-like magna-carta book on what mis-information on Cleveland engine builds that I have either got from well intentioned vendors or from this esteemed forum. And I have listened to most of the bad advise too! HAHAHA
Here's just a few suggestions I have got not once but many times;
1. You can make more power with a Windsor
2. You can't run more then 9.5:1 or 10 to 1 compression on pump gas
3. You can't run that much cam on the street
4. You can't run a hydraulic roller with that much duration
I could go on here but the fact is Dan knows his biz. Wish I had listened to him 3 years ago!
LISTEN TO HIM!
Mad Dawg Antenucci
Team Pantera Racing
470RWHP on pump gas
The 1st & only vintage car to ever start and finish 6 out of 6 Open Road Races (2004)
Some people said it couldn't be done. . .what they really meant was they hadn't done it yet!
****************************
Q: Power band best between 2500-6500 -- with that goal in mind, is a
stroker the right thing to do? I think a stroker loses the ability to rev
high and quickly?
Dan: Why do you think that?
Q: The typical Cleveland build up - with stock displacement, 4V heads,
roller cam and roller rockers seems to yield 400-425 horsepower on the engine
dynos (i've seen several magazine build-ups).
Dan: Don't rely on magazine build-ups. They are chocked full of
mis-information and poor choices. For real world numbers, a guy I know pulled right at
500 HP on the dyno with nothing more than simple closed chamber 4V 351C
with Holley Strip Dominator intake, Ultradyne solid flat tappet cam of 0.6"
lift, roller rockers, windage tray, and headers. That is with no headwork
other than a multi-angle valve job.
A well done Windsor with modern heads can get higher, with a better
low RPM response.
Q: So why is it half the Ford entrants in the EMC are building Clevelands,
despite the rules bias (Clevelands aren't allowed aftermarket blocks but
Windsors and SBC's are and there's no contingency money for Cleveland heads, intakes,
or blocks)?
Dan: By the same token, a Cleveland with modern heads will outperform a
Windsor.
Precisely why last year's winner in the EMC (Jon Kaase) chose a
Cleveland for this year's entry.
It's just harder to find modern Cleveland heads.
First off, you don't really need aluminum heads on a Cleveland as the
factory heads flow nearly 300 CFM with nothing more than a valve job. Port size
is on the large side but a stroker crank takes care of that nicely. If you
want aluminum heads for the Cleveland there are several choices including
Blue Thunder, Brodix, AFD, CHI, and Ford Motorsport.
In the end, the Cleveland will outperform the Windsor, but only after
quite a bit more $$.
Dan: A friend has a drag race Mustang with Twisted Wedge heads.
Out-of-the-box on a flow bench they weren't even close to my C302B's or A3's (and were
down 50 CFM to a set of iron 4V's). These are real numbers on a flow bench
I trust, not magazine numbers. After nearly $3K in porting and parts, the
heads flow almost as well as my C302B's and A3's.
That's with a 3.75" stroke. Some have gone to the 3.85" stroke, but I
think 377" is plenty.
There's plenty of room in the 9.2" deck Cleveland block for a 3.85"
stroke. A 4" is not really a problem either. Stroker math is straight-forward:
piston pin height = deck height - (rod length + crank stroke/2)
When I was mulling this all over, I calculated a few numbers. Note this
assumes zero deck on a block that hasn't been milled. You'll have to adjust
for whatever your block measures out at. Rearranging the equation:
deck height - (rod length + stroke/2) = pin height
9.206 - (5.778 + 3.50/2) = 1.678 r/s = 1.651 stock 351C
9.206 - (6.000 + 3.50/2) = 1.456 r/s = 1.714
9.206 - (6.125 + 3.50/2) = 1.331 r/s = 1.750
9.206 - (6.200 + 3.50/2) = 1.256 r/s = 1.771 what many circle track
racers run with Aussie 2V heads
9.206 - (6.250 + 3.50/2) = 1.206 r/s = 1.786
9.206 - (6.000 + 3.70/2) = 1.356 r/s = 1.622 popular 351C stroker
specs, uses offset ground 351C crank
9.206 - (6.125 + 3.70/2) = 1.231 r/s = 1.655
9.206 - (6.200 + 3.70/2) = 1.156 r/s = 1.676
9.206 - (6.125 + 3.75/2) = 1.206 r/s = 1.633 forged crank, popular
high rpm drag race combo with 4V heads
9.206 - (6.200 + 3.75/2) = 1.131 r/s = 1.653 pushing the pin height
limits for a street motor
9.206 - (5.950 + 3.85/2) = 1.331 r/s = 1.545 Scat steel crank, 2.75"
Cleveland mains and Windsor rod journals.
9.206 - (6.000 + 3.90/2) = 1.256 r/s = 1.538
9.206 - (6.000 + 4.00/2) = 1.206 r/s = 1.500 400 nodular iron crank
(or aftermarket)
The popular budget choices for a Cleveland are:
1. 377 (3.7" stroke, 0.030" over):
3.7" offset ground Cleveland crank with 6" rod (Olds or 2.1" journal
Chevy), custom pistons. Offset grind 351C crank to SBC journal, widen crank
journal or narrow rods (easiest), 6" rods, custom pistons. Assuming your crank
grinder works reasonably, the least expensive. If not, the 3.75, 3.85", or
4" stroke SCAT or Eagle cranks may be as cheap. Room to go to longer
rods (6.125" or 6.2", if desired. Conservative compression height and rod
ratio with room for a standard ring pack. Done right, pretty bullet-proof.
The Pantera Performance Center in Colorado stocks pistons for this combo.
2. 393 (3.85" stroke, 0.030" over):
3.85" Scat or Eagle crank with 5.95" Windsor rods or 6" Chevy rods,
custom pistons. Chinese import cast steel/iron cranks with 6" rods and custom
pistons. Also, 5140 forged steel and 4340 forged steel cranks are available.
Like a 377 but with more cubes. This is what I picked for my aluminum Fontana block (3.85" SCAT 4340 forged crank). With the 4.1" bore of my block I'll be at 407 cubic inches.
3. 408: (4.00" stroke, 0.030" over):
4.00" Ford, SCAT, or Eagle cranks, 6" rods, custom piston, 1.2"
compression height. Most cubes while keeping a decent pin height. Most power for
a given RPM (best torque) but higher piston speed. Any longer stroke and
you risk running into the block notches with the top ring. As a means of
comparison, the popular 331 and 347 cube stroker kits for the 5.0L have shorter pin heights.
Longevity is dictated by the power the engine makes, the strength of the
components, piston speed (a function of RPM and stroke), rod to stroke
ratio (side wall loading) and ring pack (narrow ring packs don't seal as well,
tend to rock at TDC). The 377 is best for high RPM in that it has the
lowest piston speed (stress on the crank), the 408 the worst but it's all
relative. Keep the 408C below say 6500 RPM and it should live. Premium components
will make any of them live.
The usual Chinese made SCAT or Eagle rods will probably suffice but for
a few more dollars you can get the much nicer 6" Oliver Superlight I-beams.
Callies has a great deal on these. I got my set for $620 IIRC. If you're in
the market for a 4340 forged steel 3.85" stroker crank, SCAT is finally
delivering again. They've been on back order for 9 months or so.
A: So, in sum, what is the ideal Cleveland build-up for aggressive street
use??
Dan: When last I heard, Mad Dog's 377C is putting down 470 RWHP on 91 octane
in a street-driven Pantera. He's running C302B heads, a Comp hydraulic
roller cam (245 deg @ 0.050", 110 LSA, 0.600"+ lift), 830 CFM tuner
Holley, 180 degree headers, etc.
> For personal reasons, I want to stick to a Cleveland block.
It's always good to sonic test the block. For a big HP effort, do a 1/2
fill of hardblock. See:
http://www.bacomatic.org/~dw/alex379/alex379a.htm
© Carmemories