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Author
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Topic: How difficult to rebuild a C-4?
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Amherst
Gearhead Posts: 246
From: Amherst, WI, USA
Registered: Aug 2000
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posted 08-26-2001 02:12 PM
   
The reason I am asking about the C-4 is because I am seriously thinking about making the 66 just a strip car with very little, if any time on the street. Then she doesn't have to be pretty, and I can just focus on safety items, engine stuff, and the like as opposed to paint and pony interiors! I already have the C-4, which I understand can be made into a great drag tranny. I understand that it probably makes more sense to just buy a B&M from summit, but if that is the case, how come everyone doesn't do it that way? There must be some advantage to doing it yourself. Any feelings on this matter?
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steve'66
Gearhead Posts: 3596
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 08-26-2001 07:06 PM
C-4s aren't hard to rebuild once you know what you're doing.  Just use good parts and it'll work great. Now I'll step aside for the c-4 experts to tell you what the "good parts" are. Don't forget the right torque converter to go with it. My older bro could rebuld a 727 (mopar) in under an hour in the pits, the c-4 is similar. SteveW
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Amherst
Gearhead Posts: 246
From: Amherst, WI, USA
Registered: Aug 2000
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posted 08-26-2001 07:34 PM
That's good to hear. Are there any good videos or books that I can buy that will walk me through the process?
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stang106
Gearhead Posts: 301
From: God's Country!... Port Alberni B.C. Canada
Registered: Jul 2001
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posted 08-27-2001 09:17 AM
While we are on the topic of C4's and racing why are C4's used over C6's? I am changing my motor from a 302 to a 351 and since my C4 is worn out I was going to use a built C6?
Dave------------------
'70 ragtop Stang,
very worn 302, ET 16.090
Keep your stick on the ice!
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steve'66
Gearhead Posts: 3596
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 08-27-2001 09:56 AM
The c-4 uses less h.p. to operate than a c-6, resulting in more net h.p. to the rear wheels. Plenty of guys are using c-4s in 10 second cars like Alex and Rob.SteveW
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Amherst
Gearhead Posts: 246
From: Amherst, WI, USA
Registered: Aug 2000
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posted 08-27-2001 10:14 AM
Not to mention C-6 tranny's are much bigger and weigh more. Hot Rod mag last year did an article on parasitic loss or something like that, and as Steve said, it does take more hp just to turn it.
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Fastback68
Gearhead Posts: 605
From: Sucat, Paranaque, Philippines
Registered: Jul 99
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posted 08-27-2001 10:36 AM
So what are the advantages of a C6? I think I know what they are in theory, but can a properly built C4 handle anything a standard C6 can?
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stang106
Gearhead Posts: 301
From: God's Country!... Port Alberni B.C. Canada
Registered: Jul 2001
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posted 08-27-2001 11:24 AM
Thanks, steve.
Do you run a C4 behind your 351? any problems? I was reading old posts from June, 2000 and am interested in your engine combination, if you don't mind. My goal is to have a 13 second street/strip car...I have a budget to build a new motor and am not sure on a few things, such as how much overlap and lift for about 9:1 compression, Windsor Sr heads, cast exhausts. I will be building a spool for the track with taller slicks so I can launch hard as well as swapping in some loose springs and 90:10 front shocks for the track. Your comments appreciated as I don't have too much technical support here in the mountains of Vancouver Island.
Dave ------------------
'70 ragtop Stang,
very worn 302, ET 16.090
Keep your stick on the ice!
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steve'66
Gearhead Posts: 3596
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 08-27-2001 12:31 PM
Dave,My daughter's '66 is a 351w which had a 3speed + od manual tranny. The 351w has Edelbrock Performer rpm 2.02/1.60 valves, 280S Comp cam, Roller rockers, Perf RPM Intake, 750 Holley (Vac), 4.11 trac-lock 9" rear, Lakewood traction bars, Et Street tires, steel wheels all around. It's best in this configuration was a 12.52 @ 109 mph.
I'm currently swapping in a 5 speed and deep sump oil pan. Hopefully the extra gear, and reduced parasitic loss of the t-5 will get the car into the low 12s. Good luck with your combo, there are many ways to do it. SteveW
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steve'66
Gearhead Posts: 3596
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 08-27-2001 12:38 PM
Oh, and 10-1 compression with the lightweight forged flat-top pistons.  SteveW
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stang106
Gearhead Posts: 301
From: God's Country!... Port Alberni B.C. Canada
Registered: Jul 2001
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posted 08-27-2001 03:04 PM
Steve,
Is 10:1 streetable or will I be retarded too much (the ignition-I knew what you were thinking) How tall a tire for the strip with those 4:11? I'll be swapping in a set of strip-dedicated pumpkin. Is the 280 grind streetable or race only? I prefer a bumpy idle, I have had good results with a solid cam in the past and will be going solid with roller rockers.
Thanks, Dave
-Don't drink too much of that excellent wine in Sonoma or Napa, I have family east of you in Auburn who I visit regularly.------------------
'70 ragtop Stang,
very worn 302, ET 16.090
Keep your stick on the ice!
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steve'66
Gearhead Posts: 3596
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 08-27-2001 04:10 PM
Dave,10-1 is fine with aluminum heads and 92 octane fuel. We run 38 degrees total timing too. Have a glass of wine on me. BTW the 280S cam is a little bumpy, but streetable. Idles about 750-800 rpm. Didn't want to go too big a cam on a street 351w and put the power curve above the rpm limits of the bottom end. SteveW [This message has been edited by steve'66 (edited 08-27-2001).]
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stang106
Gearhead Posts: 301
From: God's Country!... Port Alberni B.C. Canada
Registered: Jul 2001
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posted 08-27-2001 05:15 PM
Steve,
I concur with your thinking, I don't want the power up in the stratusphere either,
Dave
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steve'66
Gearhead Posts: 3596
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 08-27-2001 05:37 PM
Dave,4.11 gears are just about perfect with a 26" tall tire. It's about 6,000 rpm at 112mph in high gear (1-1 ratio). LOL about you're reading my old posts from June 2000. That was right after the 351w build, I think. We started with this engine and bfg drag radials, running high 13s until we got the car to hook up better. The h.p. has stayed the same, but we've worked the et down a bit. Still a ways to go too, as 110mph could run high 11's if everything else is optimal.
Good luck, SteveW
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66351stang
Gearhead Posts: 623
From: sayville,newyork
Registered: Jul 2000
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posted 08-27-2001 08:36 PM
i have a 351w bored 30 over=357, i have a worked c-4 behind it. no problems at all....
last figure i read was the c-6 use's around 22-25 hp power more than the c-4------------------
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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JAAZZY
Gearhead Posts: 649
From: Bay Area, CA
Registered: Apr 2001
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posted 08-27-2001 08:56 PM
I'm using 10.5:1 with my 347" with 91 Octane and it seems fine. My cam is probably a little too large to be streetable but the compression seems fine. Actually I could probably live with the cam as well. 
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Dave_C
Gearhead Posts: 403
From: Gadsden, Al
Registered: Aug 99
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posted 08-27-2001 09:49 PM
The weight diff from C-4 to C-6 is 42 lbs. A while back I weighed a couple on my bathroom scales. Dry w/o converter the C4 was 105, the C-6 was 147. I saved a list from a racing mag a few years ago (SS and Drag Illustrated??) To turn the stock internal rotating assembly 6000 rpm:
Powerglide: 18 hp
Turbo 350 27 hp
C-4 29 hp
Turbo 400 39 hp
C-6 41 hp
Don't remember the #'s for the Torqueflites. About 12 hp diff between the C-4 and C-6. The C-4 can be built plenty strong, but my personal opinion for the C-4 is about a 500 hp crank hp limit unless you want more maint. Yes, they will last for a while behind more, but that seems to be where they start having problems. I've been there, several of my friends have also. Above 500 hp at the crank and they start wearing out the frictions much faster. Usually don't break the hard parts if they are aftermarket, but the clutch plates only have so much friction material area. They need more maint at this level. The C-6 can handle that level with nothing more than a hi-po rebuild kit. No hardened input, no billet parts etc. A few years back I got tired of going into the C-4 and swapped to a C-6 behind my 383W. The C-4 used go to ~150 passes before needing high gear clutches. The C-6 would go close to 500 passes. That's with approx 580 hp at the crank. The car slowed down .11-.12 (1/8 mile) and 1 mph. Figure almost half of that .05-.06 was from the weight, the rest from parasitic losses. Not too much to give up to get the increased reliability in a bracket car. A buddy of mine went from a stock C-6 in his 69 Mach 1 w 460 to a full rollerized/lightened rotating assembly C-6 and picked up almost .20 in the 1/8. Same converter, no other changes. BTW, I have since went to a Powerglide and picked up what I lost on the C-4 to C-6 swap and then some. Later, David Cole
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