O.K. long of the short... My dad built a Model A drag car (very low budget). 460 bored out to a 550something. He had a C6 that was good for a while, but started to go down-hill after a while, aka wouldn't shift. Some one owed him money and traded a bbf c4 to him. No b.s. went straight from 10.46 to 9.78. I've always heard a c4 is worth about 30 horse more than the mighty c6. Now I know its true. By the way, look for him at MOKAN. Blue 31 sedan, with zoomies. If you happen to tape it, send it to me. Would be there...had a death in the family.
I think it would take a lot more than 30 HP to make a half-second improvement in your e.t. Having said that, yes, the C6 sucks about 30 HP more than a similarly prepped C4, but it is very strong. I've been running one in my street/strip '33 Willys since the 1980s with nop problems. Maybe yours was not in tip-top shape when it was installed.
never knew C4's were ever made to fit BBF..........until C6 was intro'd I thought the FMX was the big block tranny....hmmm..... learn something everyday Ray
Defineatly not stock. Also not sure if the c4 came stock with a big block. Pretty sure it did, but anyways, built c4w/460/429 bellhousing equals big results
...the convertor is the same. The fact it shifts good and hard made a huge difference. Don't get me wrong, the c6 is just about bullet-proof, but if you're struggling for a better time, there is no other way to go...
The C4 never came behind a big block from the factory, but it did come behind a 351M in mid size cars, so that bell can be used to bolt up to a 460. They are used in big block drag cars, up to 700hp, but with some beefing needed. Rebuilding the front planetary with parts from the rear, welding up holes in the front drum, etc.
There was something VERY wrong with that C-6. Seven hundreths maybe a tenth, yea. 7 tenths, no way Jose.
Jim Paquet is pretty well known for big HP C-4's, also sells an SFI C-4/FE bell, I have been contemplating it myself when I put my Falcon back together, but its a fair whack of coin just to gain a tenth, and I already have a needle bearing C-6 with an 8" converter and a cheetah valve body that would be useless to me. Before the Stock class rules went all weird, alot of stock elim guys used to fill the C-6 case with 904 TF internals, but it wasnt "legal" I was at Boise one time for the WDRS, and they tore down and bounced a certain well-known 428cj Torino for just that. http://www.business.com/company-2VKVwD/jims-performance-transmission-eaton-rapids-mi/ By the way, my Falcon went 10.70s with the C-6. So I guess with a C-4, my low $$ streetable, flat tappet cam, iron head FE would have went nines, eh? Yea, in my wildest fantasies...
C-4s can be built to handle a lot of power,but it does cost money.I've crewed on a couple of 9 second cars with C-4s behind big horsepower engines.The C-4 has a removable bell housing and there are bells to adapt it to almost any engine! To throw another trans in the mix,a friend with a mid 9 second Comet switched from a C-6 to a TH400,car went almost 3 tenths quicker! ROY.
If the C6 would have been freshened up and working properly you would have had nearly the same time improvement....
The FMX evolved from the Cruise-o-matic, great transmissions in the own right. I know the FMX was cast iron with an aluminum bellhousing, had one in a '69 Fairlane. Cruise-o-matics were a 352 & 390 mainstay from the late '50s to probably '68 or so. Bob
Exactly! In the late 70s Ford was desperate to meet CAFE standards & put C-4s behind 351W & M, where in '70 they would have had an FMX or C-6 depending on if it was a 2 or 4 bl.
Converting a C-6 over to needle bearing thrust washers is supposedly worth anywhere from a tenth to .15, depending on who you ask. I didnt do any back to back testing when i did mine, I did the bearings from day 1. A GOOD valve body, like the Turbo Action is worth around a tenth on most trans, I did that from day 1 as well. So right there, you are looking at around a 1/4 second between a decent trans and a junkyard stocker. Add another tenth to .15 for the difference in parasitic drag between the C-4 and the C-6, and you are looking at MAYBE .35-.40 between a decent C-6 and a built C-4. The original trans was seriously hurting. If I were to guess, I would say the thrust washers were chewed all to ratshit and the clutches were shot.
My buddy is a hard core Ford guy and races a glass 27 T with a BBF in super comp. After talking to his tranny guy he went with a Powerglide. The tranny shop told him "the Powerglide has years of development and is proven, why do you want to try and reinvent the wheel". It about killed him to do it but he went with the Powerglide.
I called my buddy and got some more info. He said it is somewhat common knowledge that you can run a 2-speed Power-Glide in anything that weighs 2800 lbs or less. Anything over 2800 lbs you will need a 3-speed. The Power-Glide takes around 17 hp to run where a C6 takes closer to 60 hp. The C4 takes somewhere in between 17 and 60 hp. You can use an Ultra Bell to adapt the PG to the BBF but he found the UB to be a little crude. He spent more money and went with a Reed Bell. I was wrong about his tranny guy telling him to use the PG. He researched it himself and builds his own trannys and his own engines. His car weighs 2025 with fuel and driver and has around 750 hp. He was Super Pro track champ at Tri State Raceway in Earlville Iowa (NHRA Division 5) in 2008 and 2009. He ran a limited schedule in 2010, 2011 and 2012 due to some family health issues. He is a local guru for Clevors, small and big block Fords and he knows a lot about 426 Hemis as he ran one for years before going back to Ford engines. He is retired but runs his own small speed shop. If you have questions about Fords, using the Power-Glide or drag racing in general you can contact him direct. He is a wealth of information and has great prices on speed parts. Virg Dietz Automotive Enterprises 319-393-2108
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