Corby

Nearing completion of a '66 coupe, 427 4 speed. Engine dyno'ed at 543 HP and 500 ft pounds of torque. My question is; what kind of clutch/pressure plate will live behind this kind of power without going to an exotic setup? Will not do any racing, just some spirited street driving. Thanks for any help.

65tripleblack

RAM Powergrip is max I would use for the street. Better off using the 401 pressure plate with a 300M disc. Less chatter and more drivable. The Powergrip might chatter depending on your gearing.

http://www.ramclutches.com/Products/street%20strip.htm

I have about 475 HP and I use the 401/300M combination and they do a great job.

As long as you don't put slicks on your car, you have nothing to worry about.

DansYellow66

What are you running for tires? If running a relatively stock size tire then in my opinion the clutch is probably not as critical - use a good quality, 11 inch single disc clutch - RAM, McLeod, Centerforce, LUX, etc.

If running wide, sticky tires and beefed up U-joints and half shafts then that could be a different story.

63Corvette

I would recommend a dual disc clutch, but hopefully "427HotRod" will weigh in here

novadude

How is the pedal feel on that 401 pressure plate? I want something close to stock, and I've been eying the Ram HDX set-up. I believe the GM 10.5" clutch uses the 401 pressure plate for this application.

Avispa

I had originally installed a LUK factory replacement clutch when my restoration was finished in 1999. 5 years and only 3000 miles later it blew all the friction facing off the clutch disk just running it out to 6000 RPM, fully engaged, in 1st gear. I'm not buying any more LUK clutches. FWIW,currently running a Centerforce dual-friction with no troubles since 2004 (about 11,000 miles on the clutch).

65tripleblack

RAM HDX uses the 401 pressure plate.
I'm almost sure that the HDX is the combo that I have. It is the heavy duty pressure plate with an 8 spring Marcel disc. It uses the same black, organic material on both faces and drives very nicely. Hard to quantify pedal feel. I'll tell you that I have the clutch in "quick release" position and it's comfortable for my 62 year old knees. I'll guess that it's about 10% stiffer than the stock diaphragm spring pressure plate, and much lighter than the old Borg and Beck pressure plate.

Avispa

Sorry to hijack the thread, but, Corby, what's in/on your 427 to make those power/torque numbers?

I'm running correct casting number rectangle port heads with 1.88 exhaust valves, correct dual plane intake, 10.25 compression, a Crane solid lifter cam (236/248 degrees at .050 lift) and a Holley 3310 vacuum secondary carb. I was barely able to squeeze 454 HP/440 torque out of mine.

Another 100 HP would be "da bomb"!

novadude

Thanks. I can live with 10-20% increase in pedal effort from stock. I just don't want 30-50% increase in effort.

Corby

Really no magic here. '66 427 board 40 over, oval port/open chamber heads that have been ported and polished. (these flow really well) I'd have to look at the cam card for the exact specs but it is a flat tappet full roller cam. Aftermarket duel plane aluminum intake with a Holley 950 cfm double pumper. Runs on pump gas. Just old school drag racing stuff. My engine builder is Andy Jensen of Jensen engine technology, in Nescopeck Pa.

Avispa

Thanks, Corby!

Yes indeed, ported open chamber heads and a roller cam will definitely get the job done. Figured I was leaving about 100 HP on the table with unported old school closed chamber heads.

DansYellow66

Headers versus manifolds might be responsible for part of the differences between your engines. I assume you both are talking about engine dyno figures.

Corby

Yes, definitely engine dyno.

Avispa

Engine dyno here as well.

427Hotrod

I've had great luck with the Centerforce Dual Friction,,,especially for the money. I ran one behind my 427 for years...even with slicks and 7000+ rpm shifts,,,then I reinstalled it behind the first version of my 540 (732 hp). It held up just fine. It wasn't until I went past 800 HP that it started having trouble holding the power. At that time I gave it my buddy who is still running it behind his 525+ HP 383. The pedal effort is very mild on it with no chatter issues.

You have to follow the instructions to ensure the geometry is set right, but it's easy.

I think a single plate clutch is easily capable of handling your power level.

JIM

ajrothm

We just installed a Ram HDX behind our 65' 396/425hp and it drives great. Literally no break in and it's smooth as can be. Pedal effort feels like stock. Even when trying to slip the clutch for a quick start its smooth and chatter free.

We used this same clutch on our '66 L79 a few years ago and had great luck with it so we ordered another one for the 65'.

If you're not gonna be launching hard at the strip, I think it's a great street clutch for 500hp or less.

Corby

Thanks for everyone's help. Feel like I can make an informed decision now. Summer is coming soon!