Building a C4 for 351C
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From: AL
Building a C4 for 351C
I am in the planning stages of a 351C and C4 combo. The engine won't be too wild, but I'm gonna estimate it at upper end of 400 - 425hp. Flat tops, solid flat cam, 62cc aluminum heads, Weiand Xcelerator single plane. I am wanting to put a C4 behind it, as it's what I have. I am pretty sure the trans is a 67 out of a mustang, and being an early one means it's the small input spline trans. Am I wasting my time trying to put this trans behind this motor? What would be key areas to focus on the trans to beef it up?
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From: East Central Ia
Broader performance seems to have a good background. Nothing wrong with the C4, I have had and have great ones but for HD weight and higher power I also would recommend the C6. There was a reason Ford used them in heavy load vehicles. JMO
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From: AL
It currently has an 8” with open 2.93s. I can’t see me spending the money to regear the 8”. Plan is a 9” with 3.50-3.73s and a truetrac. Car will be mainly street, maybe a footbrake bracket race here and there.
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Probably not worth doing an OD trans--
C4 parts and transmissions, from which you can see the parts list etc if this is a DIY
https://www.tciauto.com/streetfighte...er-450900.html
AOD
https://www.tciauto.com/streetfighte...351c-351w.html
They go on and on--you can step up to a six speed....
C4 parts and transmissions, from which you can see the parts list etc if this is a DIY
https://www.tciauto.com/streetfighte...er-450900.html
AOD
https://www.tciauto.com/streetfighte...351c-351w.html
They go on and on--you can step up to a six speed....
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From: AL
Well that was an option as well, adding a third pedal and a 5/6 speed. I like driving manuals, but trying to keep this as budget friendly as possible. Going to have 1.5x in the motor as I bought the car for.
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From: AL
Yeah. I paid $4k for the car a year ago. Kid blew the 302 up in it and lost interest in it. I work on his dads 70 Convertible so he gave me the 351C out of it when he put a crate 351W in its place. I think I’m gonna just go through this C4, do a rebuilt with good parts, and see what happens. If it grenades I’ll do something different. Just want the car running and driving as soon as I can. Dad ain’t getting any younger.
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From: Pa.
As the C4 evolved, other design changes were introduced. There were C4 transmissions with pan-fill dipstick tubes (blended case and bellhousing with 164-tooth flexplates). Most C4s were case-fill (notched case and bellhousing with 157-, or 148-tooth flexplates). Pan-fill C4 transmissions with 164-tooth flexplates and blended bellhousings were designed for full-size car and truck applications and are not recommended for compacts and intermediates because they just don’t fit.
The 148-tooth bell and flexplate were designed specifically for Mustang II and Pinto/Bobcat/Capri with small transmission tunnels and are very hard to locate these days. There was also a version of the C4 produced with the 385-series (429/460) big-block bellhousing bolt pattern factory installed behind the 351M and 400M raised-deck Cleveland small-blocks in the 1970s. The 351/400M C4 is extremely rare because so few were produced.
The pan-fill C4 really is more about strength for heavy-duty applications like full-size cars and trucks than anything else because the bellhousing bolts to the case outside the pump housing. Case-fill C4 transmissions are light-duty; the bellhousing bolts to the front pump instead of the main case.
The 1964–1969 C4 input shaft and clutch hub size was .788 inch with a 24-spline on both ends. In 1970, Ford gave the C4 a larger input shaft and clutch hub measuring .839 inch with 26 splines on both ends for improved durability. From 1971 to 1982, the C4 had a split-spline count. It had a .839-inch input shaft with a 26/24-spline configuration, meaning a 26-spline at the torque converter and a 24-spline at the clutch hub.
C4 valve body variations are important to note because they’re significant to your transmission-building project. At this time, I’m aware of at least four different types of C4 valve bodies and I suspect there are more out there. For 1964–1966, there’s the Dual-Range/Green Dot valve body. At a glance, the Dual-Range valve body looks identical to 1967–1969. Internally, it has different valving and shift programming.
The 148-tooth bell and flexplate were designed specifically for Mustang II and Pinto/Bobcat/Capri with small transmission tunnels and are very hard to locate these days. There was also a version of the C4 produced with the 385-series (429/460) big-block bellhousing bolt pattern factory installed behind the 351M and 400M raised-deck Cleveland small-blocks in the 1970s. The 351/400M C4 is extremely rare because so few were produced.
The pan-fill C4 really is more about strength for heavy-duty applications like full-size cars and trucks than anything else because the bellhousing bolts to the case outside the pump housing. Case-fill C4 transmissions are light-duty; the bellhousing bolts to the front pump instead of the main case.
The 1964–1969 C4 input shaft and clutch hub size was .788 inch with a 24-spline on both ends. In 1970, Ford gave the C4 a larger input shaft and clutch hub measuring .839 inch with 26 splines on both ends for improved durability. From 1971 to 1982, the C4 had a split-spline count. It had a .839-inch input shaft with a 26/24-spline configuration, meaning a 26-spline at the torque converter and a 24-spline at the clutch hub.
C4 valve body variations are important to note because they’re significant to your transmission-building project. At this time, I’m aware of at least four different types of C4 valve bodies and I suspect there are more out there. For 1964–1966, there’s the Dual-Range/Green Dot valve body. At a glance, the Dual-Range valve body looks identical to 1967–1969. Internally, it has different valving and shift programming.
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