Big block clutch

bhill

Member
Gonna run 420 cc
Crank is 1 inch any pointers on clutch set up I’ve heard problems of these big blocks burning up clutches. Should I run 1 inch or turn crank down for 3/4 clutch
 
Don't turn the crank down. We've done it and had no real issues on smaller builds, but also broken cranks on bigger builds.
You can use a 1" clutch, but you WILL kill friction discs quickly.
I'd strongly suggest a jackshaft, as you'll burn through 1/4 as many friction discs.
= So much better solution.

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alvin l nunley

Premium User
What clutch? If it's a disk clutch, how many discs? I've never seen a dyno curve on that engine, do you have one?

I'm not aware of The difference in clutch performance between the 3/4 and 1 inch clutches.

I'm thinking a 3 or 4 disk clutch would hold it. I'm sure that engine produces a lot of low end torque.
 

flattop1

Dawg 89
Hillard has a 1" drum clutch , might be worth a try .
Might burn it up as noted and go too jackshaft anyway .
 

nobozos

Member
What about a Birky and jackshaft? Pretty much bullet proof on my 270. I would think Kevin could set ya up. Later Chuck.
 
What about a Birky and jackshaft? Pretty much bullet proof on my 270. I would think Kevin could set ya up. Later Chuck.
Years ago Bobby Baldwin had Kevin make one for a JR Billet 486cc and I believed he loved it. Kevin make it for your setup just tell him what you have and what RPM to engage. He can tell you what engine driver you need and it will be bullet proof.
 
Years ago Bobby Baldwin had Kevin make one for a JR Billet 486cc and I believed he loved it. Kevin make it for your setup just tell him what you have and what RPM to engage. He can tell you what engine driver you need and it will be bullet proof.

is Bobby still around? I remember that setup pretty well. Used to talk every now and then but that had to have been at least 10 years ago.
 
4 disc Bully clutch on a jackshaft. Practically bullet proof. Easier on the crankshaft and much easier on the discs. I run three big blocks and after setting them up never had a clutch, crank or jackshaft related failure. It's a little more expensive upfront but it will pay for itself in one season.
 

spincycle

Premium User
I've got a Tim Eilts 4 disc clutch set up on a Buller jackshaft with a 57 tooth 30mm pulley on it if you're interested....
 
What clutch? If it's a disk clutch, how many discs? I've never seen a dyno curve on that engine, do you have one?

I'm not aware of The difference in clutch performance between the 3/4 and 1 inch clutches.

I'm thinking a 3 or 4 disk clutch would hold it. I'm sure that engine produces a lot of low end torque.
Hi Al,
The 3/4-inch and one inch "clutch" refers to the size of the crankshaft the clutch is mounted on. Typically small block clones, Briggs engine and flathead engines have 3/4 inch crankshafts and big block engines have 1-inch crankshafts.
 

alvin l nunley

Premium User
Hi Al,
The 3/4-inch and one inch "clutch" refers to the size of the crankshaft the clutch is mounted on. Typically small block clones, Briggs engine and flathead engines have 3/4 inch crankshafts and big block engines have 1-inch crankshafts.
Maybe you're confused, I never asked any questions about crankshaft size.
 

95 shaw

Premium User
^^^^^^^
My money is on the one not laying on the track with the end of the crank still bolted to it as being the better performing clutch.

To finish first, first you must funish.
 
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