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  FMX to C-4 or C-6. Which would you choose?

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Author Topic:   FMX to C-4 or C-6. Which would you choose?
skips69
Gearhead

Posts: 346
From: Catlin, IL USA
Registered: Mar 2001

posted 04-08-2001 12:56 AM     Click Here to See the Profile for skips69   Click Here to Email skips69     Edit/Delete Message   Reply w/Quote
I have a 1969 FB with the original 351W 4V. It has been rebuilt and now has the Edelbrock RPM package rated at 400 HP. My FMX and 3:00 to 1 open diff just aren't letting the engine live up to it's potential. I will tackle a new set of gears soon (3:50 to 1), my dilemma lies with the tranny now. I have a C-4 and a C-6 at my disposal, but don't know which to have rebuilt. The car will see mostly show duty, with the occasional green light to red light romp. Any opinions of which tranny to use? Will my crossmember work? Can I use original driveshaft with either? How bad will my speedometer be off? Any other tips, suggestions, or problems I may be missing by making this swap? Thanks for your time.

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steve'66
Gearhead

Posts: 9555
From: Sonoma,CA,USA
Registered: Mar 2000

posted 04-08-2001 04:24 PM     Click Here to See the Profile for steve'66   Click Here to Email steve'66     Edit/Delete Message   Reply w/Quote
Skip,

Go with a built C-4, I hear they use much less h.p. than any other and are lighter too. Can't help you with fit, but others will.

SteveW

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66351stang
Gearhead

Posts: 711
From: sayville,newyork
Registered: Jul 2000

posted 04-08-2001 11:09 PM     Click Here to See the Profile for 66351stang   Click Here to Email 66351stang     Edit/Delete Message   Reply w/Quote
i have a 66 coupe with a 351svo, and c-4
the trans is worked, i had a c-6, to much modification to do also the c-6 is approx.40lbs heavier. also take about 30hp more to operate. the c-4 with some modifications will hold up fine.

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ponycar66,have you flown in a ford latley???????
66-COUPE W/351SVO
glad i had a v-8 !!!!!!
84.5 gt350-61 falcon 302
have a great day!!!!!!!!

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kid vishus
Gearhead

Posts: 6617
From: middle of NC
Registered: Oct 2000

posted 04-08-2001 11:42 PM     Click Here to See the Profile for kid vishus   Click Here to Email kid vishus     Edit/Delete Message   Reply w/Quote
I run a c4 in my racecar and it holds up fine. Of course it has been modified , but I would not be afraid to put a c4 in any street car. I ran a stock c4 in my 70 behind a warmed 351C and never had any problems with it.
As for parts swappin, I dont know. I know the driveshaft and crossmember for the c4 and c6 are quite different, but I dont know about the fmx.

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JT
Gearhead

Posts: 200
From: Pearland, Texas, USA
Registered: Oct 2000

posted 04-09-2001 06:17 PM     Click Here to See the Profile for JT     Edit/Delete Message   Reply w/Quote
I've got a C4 behind a basically stock 351W in my '68 coupe. I like the combination. I just wish I had an overdrive for cruising.

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JT
'68 Coupe w/351W

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mustangs68
Moderator

Posts: 25375
From: Buckroe Beach Va MCA#39406 M&M #12 Member Mustang Club of Tidewater
Registered: May 99

posted 04-09-2001 08:42 PM     Click Here to See the Profile for mustangs68   Click Here to Email mustangs68     Edit/Delete Message   Reply w/Quote
I have a C-4 that has TCI parts i it..I love it!

now about them gears
sam

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HHuggins
Gearhead

Posts: 259
From: Laguna Niguel, CA
Registered: Feb 2001

posted 04-10-2001 03:05 AM     Click Here to See the Profile for HHuggins   Click Here to Email HHuggins     Edit/Delete Message   Reply w/Quote
Skips,

Tell me more about that Edelbrock RPM package. What was the cost? I'd really like to look into that for my 351W.

Harley

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1970 Mach I
http://www.geocities.com/hh_machi/

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68 S-code GT
Gearhead

Posts: 3289
From: Sayreville, NJ, US
Registered: Mar 2000

posted 04-10-2001 07:15 AM     Click Here to See the Profile for 68 S-code GT   Click Here to Email 68 S-code GT     Edit/Delete Message   Reply w/Quote
Your FMX cross member should work with the C$ with no problems. I had a 67 with a 351W and FMX and it had the C4 cross member. The yoke on the driveshaft is different I think though.

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skips69
Gearhead

Posts: 346
From: Catlin, IL USA
Registered: Mar 2001

posted 04-10-2001 10:01 AM     Click Here to See the Profile for skips69   Click Here to Email skips69     Edit/Delete Message   Reply w/Quote
Thanks to all for responding. It sounds overwhelmingly like all are in favor of the C-4 swap. I will create a new post asking for technical information, as well as past experiences with this swap.

Harley - The Edelbrock Performer RPM package basically consists of their carburetor, cam and lifter's, dual plane intake and assembled aluminum heads. It is also advised to run no more than 9.7:1 compression pistons and run 92+ Octane gas to get the full benefit. The kit cost about $1500 3 years ago through JEG'S, and is advertised as producing 400 HP and 412 FT Pounds of Torque. It has a very strong power band and winds up to 5,500-6,000 RPM's nicely. As mentioned though, the trans and rear are holding it back. I also run a 2 1/2" mandrel bent dual exhaust with an X pipe and two Flow master stage II muffler's bolted to long header's. It sounds sweet!

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Moneymaker
Administrator

Posts: 27660
From: Lyons, IL, USA
Registered: May 99

posted 04-10-2001 11:19 PM     Click Here to See the Profile for Moneymaker   Click Here to Email Moneymaker     Edit/Delete Message   Reply w/Quote
C-4!

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Alex Denysenko Co-Administrator and Moderator NHRA/IHRA/SRA member
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link

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