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Just a question regarding the stock 4 barrel intake on a 289. Is this such a bad intake or what are the rpm limitations considering it was used on the 271hp 289. I am curious if it provides a good all round torque curve or does it fall flat at 5500 and up. Is this a idle to 5500 intake.



Cheers

Greg:)
 

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My book says that the peak 271 HP is @ 6,000 RPM but I'd say the manifold isn't much good up there. I would also venture a guess that almost any aftermarket aluminum manifold would be a huge improvement provided you aren't using a Victor Jr. on a stock 289. ;) I've never actually seen a TQ/HP curve of a stock HiPo 289, but I'd like to.

Not only are you starting with much better manifold technology you're also dropping a lot of weight at the same time.

John
 

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Discussion Starter #3
Running an f4b right now and an old Post from Joe Sherman said that there was only 5hp between the f4b and the stock cast 4 barrel on the dyno. Wondering if the old cast had better low end compared to the f4b with the large uneven runners .




Greg
 

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I had a HI-PO 271 back in the day, 65 mustang, Yes I am very old lol. All stock as there was not a lot of stuff around then. That little rascle would rpm pass 6700-6800 easy. Of course pass about 5800 it wasn't to much, just sounded GREAT. I always thought good headers and intake would have made a hell of a difference. Oh well just not around back then (headers where) It was always lead most of the race and hang on that last 2-3 hundred feet. Lots of suprised GTOs and 396 chevys, fun fun fun.
 

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I had a HI-PO 271 back in the day, 65 mustang, Yes I am very old lol. All stock as there was not a lot of stuff around then. That little rascle would rpm pass 6700-6800 easy. Of course pass about 5800 it wasn't to much, just sounded GREAT. I always thought good headers and intake would have made a hell of a difference. Oh well just not around back then (headers where) It was always lead most of the race and hang on that last 2-3 hundred feet. Lots of suprised GTOs and 396 chevys, fun fun fun.
Yes, they (stock) are good intakes. Comparative flow datas are available. John (OLD).
 

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In the 1966 Ford Hi Performance catalog (pg 18) substituting a C6AZ cast
iron intake and Autolite 4100 4 barrel carb on a 289-2V is claimed to be
a 7 to 10 HP increase over the cast iron 2 barrel intake and Autolite 2
barrel carb. In the later Ford Muscle Parts catalog, Ford presents several
stages of modifications for the SBF with Stage 1 (Impressor Kit) being the
addition of a Holley 600 CFM carb, C90X aluminum dual plane intake and an
open element air cleaner. The claimed increase was 31 HP (page 27). The
C90X intake was developed by Ford for the 1969-1979 351W-4V head conversion
package which also included a higher performance cam, higher compression
pistons, headers and optional larger valves. When Jack Roush built the
1979 Indy Pace Car Mustang, he chose a C90X intake

Alex Denysenko moderates the MustangsandMore.com forum. He holds IHRA
and NHRA national records with his 289 Mustang in the SuperStock L
Automatic class, and has done a lot of dyno testing on the SBF. Based
upon his dyno and drag testing, Alex ranks the high rise SBF dual plane
intakes as:

Best: FoMoCo C90X
Good: Edelbrock Air Gap, Edelbrock Performer RPM, FoMoCo Shelby
lettered, FoMoCo Cobra lettered
Fair: Edelbrock F4B
Poor: Weiand Stealth, Colt 65

He also lumps the single plane Weiand Xcelerator and Torker 289 in
the poor category, along with the Offy Dual Port and Offy 360. He rates
the Victor Jr. as the best horsepower intake and the C90X as the most
flexible. Super Ford magazine did a SBF intake manifold flow comparison
test in the early '80's. Jim Miller of JME did the test and the 5 intakes
tested were all provided by Alex. They included an Offy Port-o-Sonic,
a C90X FoMoCo, a Shelby Ram Box, an Edelbrock Toker 289, and an Offy
Dial-a-Flow. The Torker 289 was the worst performer of the group.
Second best was the FoMoCo C90X. Alex claims the C90X still bests the
latest Edelbrock Air Gap Performer RPM in making power over a wide RPM
range. As far as low profile intakes go, he rates the factory cast iron
289 4V intake as decent to 5500 RPM on a 289/302 with a litle match porting
and puts the Edelbrock Performer in the same category. For mildly modifed
289 and 302 engines, he likes the Weiand Stealth.

Be aware there were several versions of the C90X (including repros).
The real ones had large FORD letters or a blank pad. The repos sometimes
say COBRA or even COUGAR. A while back I did a side-by-side comparison between
a real C90X Ford intake and a Shelby S2MS intake. 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), bottom side corner series of 4 stamped letters

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.

Alex also had this to say about the Ford Tri-Power vs C90X. "Here is what I can
tell you from past personal experiance on MoneyMaker (his 289 Mustang) 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 deuces as they worked well and looked very
cool but they were never as good as a C90X and a good DP single 4."
 

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Discussion Starter #10
Thanks Daniel


Great article. Had lot's of info and not sure if the f4b is right for my combo. Could be a better choice.


Cheers

Greg
 
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