Thread: Muncie Question

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Well I have had my 496 in the slomaro for a few weeks.
Now I have my 9" waiting to be bolted up (being lazy isnt helping this cause)...i know my new rear will be ok with the 503hp....but can my M21 handle some of the abuse?...or do i need to look for something new.
The tranny has just been rebuilt, and i have been told that a Muncie cant really be improved except for better forks and syncros which it already has.
New shaft as well.

Thoughts?

How are you going to use the car? On the street or at the strip? Street tires or slicks? What rear axle ratio?

M20's and M21's were put behind a lot of high HP muscle cars in the 60's. I ran an M20 in a GTO behind a 400, bored .030, 12:1 compression, Crane hydraulic 308/316 .544/.561 (with 1.65 Ram Air V rockers), 850 double-pumper on a Tarantula manifold, mechanical advance Unilite, HD Scheifer clutch & flywheel, 4.10 posi. I ran 10" wrinklewalls on Wednesday bracket night at Cornhusker Raceway in Omaha. Launched at 7,000, shifted at 6,500. Probably 30-40 passes a year for 3 years. Flogged it a bit on the street more than a few times too. I drove the car stock for 10 years before that. Rebuilt the trans once, with all new synchros and bearings. Never broke a thing.

But, that was just me. Your mileage may vary.

Henry thats some good rev's out of a 400 poncho!

I also had a M20 behind the 455 I had in my 72 Gto, had a 850 holley, single plane, 10.5:1, ported heads,.540/230 cam with 373 gears and 10" M&H's. Use to launch at about 5600rpms and the car was a weekday driver&weekend racer and I never had a problem with the trans in the 3 years I owned that car.

plus ya just gotta love the whine of a M20 in first gear

BG

Correction that car had 3:55 gears not 3:73's

Then on the other hand. I had a C/Gas car, that split cases, stripped clusters, bent and broke the teeth on second gear. Twisted an input shaft. Eight Muncies in two years.

Went to a Borg-Super T-10 and never broke another trans..Just about everything else in the drivetrain!

What kinda power where you putting through it Bob? because I'd say I probably wasnt putting more than about 425HP or there about through mine.

Henry thats some good rev's out of a 400 poncho!

Goat,

Was that the smartest way to run it? Probably not, but:

a. With that cam, carb and single-plane manifold, I had to.

b. I didn't know any better.

Never broke anything in the motor either.

That GTO was charmed until I sold it. About two weeks after th guy bought it from me, he was rear-ended at a stoplight by a drunk going about 60. Never saw it coming, never knew what hit him. The rear bumper was somewhere up near the dash.

Super T-10's are good, so are toploaders. When the horsepower gets serious I still get out my old trusty Doug Nash 5 speed. As a concession to old age (or common sense) I will probably get one of the new Richmond 5 speeds for the Ranchero, I would like having a trans with synchros !! The old "comp" version of the Doug Nash 5 speeds are non snychro, but boy do they shift nice going down the quarter!!

I don't think the Muncie's are rated for that much power, but maybe you can get away with it, Goat and Henry did.

Dave,

"Getting away with it" is what hot rodding is all about!

Some days you eat the bear, some days the bear eats you.