For the better most part I drive my ‘68 L68 427 Tri-power pretty civilized but once in awhile I’ll play. The engine has a little more cam than factory and throttle response is instant.
The other day I launched it a little harder off a light and I smelled clutch burning. Figured I must have of ridden the clutch, didn’t think it did but my nose said I did.
Today I just nailed it while dropping the clutch and cooked the tires for about 150’+ … again there’s that burnt clutch smell. I’m thinking now there’s the possibility that the engine under full throttle is over powering the clutch.
Could this be so ? If I’m not on it hard there’s no issue.
Also I looked up a new clutch assembly in the Zip catalog and it listed an 10.4” and 11” . Does the big block 427 use the 11” or is this something I’ve got to remove to know for sure what I have ?

 

Yes the big block should have the 11". clutch. See if you can read the casting number on the bell housing, that will tell you the size of the flywheel.

 

thank you!

 

No the 68 used a 10.5. I have a 10.5 Mcleod behind my 396 but its rated for 550 hp. When i was building up my 327 i bought the revvommended clutch and found out, just like you it wasnt rated for the torque and hp i had. You need to upgrade your clutch. On mcleod clutches its the disc that is different , the pressure plates are the same.

 

Apparently there are 2 that were used in ‘68 according to the parts sources I’ve checked. How’s the peddle pressure on the McLeod clutch ?
The Dodge 5500 dually I drove for awhile after retiring had a clutch that had my knee crying after 15 minutes in traffic. Some of the new Ford Shelby dragpak cars I’ve driven have horribly hard clutches too.
One thing I was happy about with this car is that the clutch was manageable but if the engine is overpowering it …
Guess to get one that will hold it it’s going to mean more peddle pressure.

 

Ok I reread that, so the peddle pressure would be the same then and all I have to do is swap in a new disc ?

 

I have had problems with my left knee since my High School days when I dislocated my left knee cap. I don't do well with a heavy, hard to push Clutch pedal so when I rebuilt my 427 as an L88 engine I used a Centerforce stage 2 clutch assembly. I have really been happy with that clutch assembly as the pedal pressure is light to moderate and the gripping power is great even with 500+ horsepower and tons of Torque. The Centerforce Clutch has more holding power as the engine speed increases and is able to handle Hp very effectively. It has a much nicer pedal feel over the original clutch parts that were on the Corvette when I bought it. The old idea that you need a "heavy clutch" to hold Hp is not entirely true as the Centerforce clutches are very effective but yet have a great pedal feel. I have been caught in heavy traffic and was still able to walk afterwards so I have been very happy with the Centerforce components.

The only time it ever broke loose was when my throttle stuck wide open on a curvy road and my first reaction was to push the brake pedal as hard as I could while playing with the gas pedal trying to get it to release. As I held the brake pedal the clutch finally started to slip but that was the only time it ever broke loose in the 2 decades of use.

When you replace the clutch you should also replace the pressure plate in addition to the fiber disc. The flywheel should be re-surfaced if the surface is not perfectly smooth. I will be using another Centerforce clutch assembly when I get to the point of needing a new clutch. I also would suggest the Steeroids Clutch linkage as it helps smooth out the pedal movement as well.

 

Yes if you have a McLeod clutch. The pedal pressure was never an issue for me. Ive Gone to a hydraulic clutch from McLeod And its even better