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  Mustangsandmore Forum Archive
  Ford Racing
  C90X Ford versus S2MS Shelby intake

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Author Topic:   C90X Ford versus S2MS Shelby intake
Daniel Jones
Gearhead

Posts: 972
From: St. Louis, MO
Registered: Aug 99

posted 12-12-2001 06:30 PM     Click Here to See the Profile for Daniel Jones        Reply w/Quote
Last night, I did a side-by-side comparison between a C90X Ford
intake and a Shelby S2MS intake, trying to determine if they were
reproductions or the real deal. Here are my notes:

C90X Intake:
Blank pad behind the thermostat housing
2 tapped bosses behind thermostat housing
Firing order on the forward runner
C90X 9424B on back runner
2 hole (oval) plenum
2 tapped throttle cable bracket bosses
2 tapped bosses on aft runner for vacuum
tin heat shield (oil splash) on bottom (held by 2 blind rivets)
ports measure 1" wide by 1 7/8" tall
additional threaded boss (small diameter, down low in front)

S2MS Intake:
Raised "Shelby" lettering behind the thermostat housing
2 tapped bosses behind thermostat housing
Firing order on the forward runner
S2MS 9424A on back runner
4 hole (round) plenum
no throttle cable bracket bosses
2 tapped bosses on aft runner for vacuum
tin heat shield (oil splash) on bottom (held by 4 blind rivets)
2 cylindrical posts on bottom side
ports measure 1 1/16" wide by 1 15/16" tall

Both castings were approximately the same height.

The picture on page 27 in my reprint of the Muscle Parts catalog
looks identical to the C90X that I have, right down to the blank
pad and threaded bosses. I also have an article about the 302
Jack Roush built for the '79 Indy Pace Car Mustang and it shows
a picture of a C90X intake that is identical to mine, except it
has raised "FORD" lettering instead of the blank pad. My question
is: Do I have a real C90X or a reproduction? Did the C90X have
289/302-sized ports or DOOE type 351W ports? I've always assumed
that, since the C90X was designed by FoMoCo for the 351W head
conversion package, the ports would be 351W size. Maybe they
sized the ports to fit 289/302 heads, expecting the user to port
match to the 351W size, if need be.

Also, Alex do yo have an idea of how a FoMoCo 3x2 barrel dual
plane would stack up against the C90X on a street/strip 289/302?

Thanks Much,
Dan Jones

Moneymaker
Administrator

Posts: 29200
From: Lyons, IL, USA
Registered: May 99

posted 12-13-2001 02:22 PM     Click Here to See the Profile for Moneymaker        Reply w/Quote
Dan, I have in my possesion an S2MS and a C90X at this time. I have had over 50 C90X's over the years and a dozen or so Shelby versions. They (C90X) ALL have FORD block letters cast into them if they are original. They ALL have 351W sized (close) ports. They are about 1/4 taller than the S2MS. The runners are noticably larger. If I was to speculate, you have a reproduction.

------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00 & '01
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link

ToddStyles
Gearhead

Posts: 146
From: Memphis, TN USA
Registered: Aug 99

posted 12-13-2001 04:14 PM     Click Here to See the Profile for ToddStyles        Reply w/Quote
I've got the C9OX on my 289 and one in the garage that has been port-matched. I've saw a bunch in the late 70s early 80s that had the FORD letters ground off. Back then it wasn't necessarily "cool" to run OEM parts.
Todd.

------------------
1965 2+2 GT, A-code 289 w/351 heads, Autolite 4100 on a C9OX intake. T-5, 9" Versailles w/4.11 t-lock.

Daniel Jones
Gearhead

Posts: 972
From: St. Louis, MO
Registered: Aug 99

posted 12-13-2001 05:50 PM     Click Here to See the Profile for Daniel Jones        Reply w/Quote
Alex and Todd,

Thanks for the input. I'll measure the plenum depth and internal runners. Maybe we can compare with your real C90X's. The fact that the ports aren't 351W probably does mean it's a repro. It might be a good intake for someone with 289 heads though. I've got DOOE 351W heads that I wanted to use it with so I'll keep looking for a real one.

The blank pad doesn't appear to have been ground on. The casting looks very uniform in that area though I suppose the whoul intake could have been bead blasted sometime in it's past. The fact that the Muscle Parts catalog shows one with a blank pad makes me think there were some cast that way.

Thanks Much,
Dan Jones

Moneymaker
Administrator

Posts: 29200
From: Lyons, IL, USA
Registered: May 99

posted 12-13-2001 06:36 PM     Click Here to See the Profile for Moneymaker        Reply w/Quote
Dan, there is one absolute dead nuts means of identification. Turn the intake over to the bottom side and look in one of the corners. There should a a series of letters stamped (not cast)in the lifter valley side intake.
Also I just noticed your question about the Tri-Power vs C90X. Here is what I can tell you from past personal experiance on MM circa 1972 or so. With stock 20k mile HIPO short block, well tuned by me Tri-Power, C7FE cam, Hooker headers, 5.14 gears and a 4 speed I could run 13.0's driving the car to the track in the morning air. It would slow to 13.20's as the summer day progressed. Over the winter I did a competition valve job and installed GT-40 valves in the otherwise stock HIPO heads, and used steel shim head gaskets. No other changes were made. I was rewarded with my first 12 second time slips and ran a best of 12.79 @ 109 MPH. (clocks and timers used a different method of calculating MPH in those days)
I picked up a C90X from my friendly Ford dealer and purchased a 4779 Holley 750 DP carb on the urging of smarter than me (at the time ) mentors. I made the swap and drove the car. It actually felt a bit slower seat of the pants overall, but was much more responsive in the lower RPM range. A trip to the track the following Sunday netted me a 12.50 @ 111 MPH time slip on the first pass. I ran 12.50's all day and won my class convincingly. I never looked back again. I loved my three dueces as they worked well and looked very cool, but they were never as good as a C90X and a good DP single 4.

------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00 & '01
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link

Daniel Jones
Gearhead

Posts: 972
From: St. Louis, MO
Registered: Aug 99

posted 12-14-2001 11:06 AM     Click Here to See the Profile for Daniel Jones        Reply w/Quote
I checked my C90X intake last night and it does have 4 small stamped letters in one of the corners (back corner on thermostat side). They are blurred but it looks like 0355 or somesuch. Do those sound like the numbers you were referring to, Alex? I also got in touch with a guy with a FORD lettered C90X and will be examing it tomorrow.

Thanks Much,
Dan Jones

Moneymaker
Administrator

Posts: 29200
From: Lyons, IL, USA
Registered: May 99

posted 12-14-2001 11:22 AM     Click Here to See the Profile for Moneymaker        Reply w/Quote
Dan, all of the REAL ones have OECO stamped in them. If I remember correctly Ford Power Parts has been repoping them with or withour the cast in block letters for quite some time. They are not exact dupicates.

------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00 & '01
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link

Daniel Jones
Gearhead

Posts: 972
From: St. Louis, MO
Registered: Aug 99

posted 12-14-2001 12:41 PM     Click Here to See the Profile for Daniel Jones        Reply w/Quote
It could be OECO. The letters are faint and I was just guessing. If all goes well, I'll see what how the FORD letered C90X compares.

Also, thanks for the tri-power info. It's for a friend of a friend who wants to run one.

5.14 gears on the street! Wow, that must have really revved out on the highway.

Thanks Again,
Dan Jones

Moneymaker
Administrator

Posts: 29200
From: Lyons, IL, USA
Registered: May 99

posted 12-14-2001 01:53 PM     Click Here to See the Profile for Moneymaker        Reply w/Quote
With L-84 x 15 limosine tires (tallest tires that I could make fit on the back air shocks and all), on a 1200 mile road trip to see my brother it would spin about 4000 RPM at 75 mph. I have always been a little "gear happy" as if you all didn't already know that!

------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00 & '01
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link

cobraii351
Journeyman

Posts: 87
From: Altoona, PA
Registered: Jun 2000

posted 12-14-2001 03:14 PM     Click Here to See the Profile for cobraii351        Reply w/Quote
Along the same lines I have a C9?? Shelby lettered windsor intake. What kind of rpm range is this for? I have a mild 351 with a 600dbl pumper. The cam I have in it is the FMS M6250A332. Is this a decent combo for the street?

Moneymaker
Administrator

Posts: 29200
From: Lyons, IL, USA
Registered: May 99

posted 12-14-2001 03:26 PM     Click Here to See the Profile for Moneymaker        Reply w/Quote
That is a GREAT 180 degree intake. Works well from idle to 6000 RPM. You carb is really too small for the cubes though. A 750 DP would wake things up a bunch.

------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00 & '01
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link

Daniel Jones
Gearhead

Posts: 972
From: St. Louis, MO
Registered: Aug 99

posted 12-16-2001 05:08 PM     Click Here to See the Profile for Daniel Jones        Reply w/Quote
I got a chance to check out another C90X intake this weekend. A local guy has it for sale for $250. It is essentially identical to mine, except it has the FORD lettering where mine has a blank pad. It has the stamped OECO as does mine (comparing the two, I can now tell what the blurry stamping reads). The plenum depths are the same. His ports have been matched to an intake gasket but it appears that they were the same size as mine, originally.

Alex (or anyone else with a C90X), if it's not too much hassle, could I get you to measure your C90X's intake plenum depth
(stick a ruler down both sides)?

The mystery continues...

Thanks Much,
Dan Jones

ToddStyles
Gearhead

Posts: 146
From: Memphis, TN USA
Registered: Aug 99

posted 12-16-2001 06:31 PM     Click Here to See the Profile for ToddStyles        Reply w/Quote
I checked the one not on the car and it has the 0ECO stamping. The plenums measured ~ 2.5 and 4.5 inches.
Todd.

------------------
1965 2+2 GT, A-code 289 w/351 heads, Autolite 4100 on a C9OX intake. T-5, 9" Versailles w/4.11 t-lock.

Moneymaker
Administrator

Posts: 29200
From: Lyons, IL, USA
Registered: May 99

posted 12-17-2001 11:14 AM     Click Here to See the Profile for Moneymaker        Reply w/Quote
I'll do some measuring later.

------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00 & '01
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link

Daniel Jones
Gearhead

Posts: 972
From: St. Louis, MO
Registered: Aug 99

posted 12-17-2001 12:34 PM     Click Here to See the Profile for Daniel Jones        Reply w/Quote
My plenum measured out at 2 5/8 and 4 3/4" deep. Todd, does your C9)X have 351W or 289 size ports?

Thanks Much,
Dan Jones

ToddStyles
Gearhead

Posts: 146
From: Memphis, TN USA
Registered: Aug 99

posted 12-17-2001 02:22 PM     Click Here to See the Profile for ToddStyles        Reply w/Quote
i'll have to measure them when I get home. I'm pretty sure they've been worked over though. the other intake is on the car at the body shop.. and will be for a couple more months. Todd.

------------------
1965 2+2 GT, A-code 289 w/351 heads, Autolite 4100 on a C9OX intake. T-5, 9" Versailles w/4.11 t-lock.

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