Close Ratio Muncie

427carl · A Poncho Legend!

Close Ratio Muncie

4SPEED427 · A Poncho Legend!

I know you didn't ask for opinions Carl but I don't think you'd ever want to. I wouldn't even want to try it with 3.31. With 3.55 or lower only.

67rag396 · Poncho Master!

From what I read over the past 2 months you would not be happy with a close ratio and 3.08 gears. There was a reason for GM to put the M 21 or 22 with 3.55 or lower gears. I selected the M 20 again to match with my 3.31 rear end.

Wide ratio (M 20) 1st gear 2.521 X rear 3.08 = 7.765 gearing
Close ratio (M 21 or 22) 1st gear 2.199 X 3.08 = 6.773

Close 2.199 X 3.55 = 7.806

Ultimately you could drive either one, but what do you want. Slip clutch

or slip tires whenever desired

.

Rick

427carl · A Poncho Legend!

I had heard and read those facts before.. biggrin

I had a chance to buy a M21 and my car has "so much bottom end" (seriously will not hook up with 350 turbo first gear, which I think is 2.54) I like the 2.73 gears, and have a 3.08 posi set for it.. (car will run 13.40@101 with 2.73) Guess I will try to find a M20...THANKS

4SPEED427 · A Poncho Legend!

You would hate it in stop and go traffic. It would take a lot of feathering from a dead stop.

My 66 427 M20 4 speed car was 3.31, 14" tires (I forget the height but not very tall) and even that seemed like it needed a lower rearend gear. I think it was because it's such a heavy car. A guy might get away with it in a Chevelle but a 4300 pound car is not anxious to get moving.

Listen to us old guys Carl. Hey, wait, I think you are one of us........

427carl · A Poncho Legend!

Carl Stevenson wrote:

You would hate it in stop and go traffic. It would take a lot of feathering from a dead stop.

My 66 427 M20 4 speed car was 3.31, 14" tires (I forget the height but not very tall) and even that seemed like it needed a lower rearend gear. I think it was because it's such a heavy car. A guy might get away with it in a Chevelle but a 4300 pound car is not anxious to get moving.

Listen to us old guys Carl. Hey, wait, I think you are one of us........

I hear you! and I run 27 inch tires... 3.55 and M20 would be more like it???

4SPEED427 · A Poncho Legend!

I would say so. Seems to me I had about a 225 70 14 with my setup.

67rag396 · Poncho Master!

When I first got my car it had 215/70 14" tires (26" tall)
M 20 3.31 gears and I could "get rubber in all 4 gears". 4th was a tiny chirp but you get the idea.
Then changed to 235/60 15" (26" tall) and could only get a chirp in 3rd nothing in 4th. Tires are wider. The car still moved really well off the line.
Before going to California in 2006 I put 235/70 15" (28" tall) on the car so I could keep up with seventy2plus2. The car then felt sluggish and could barely get a chirp out of 2nd gear.
What I am saying, is that like most of this stuff you need to consider all of the pieces and the targets. Rubber in all 4 gears, quarter mile optimization or highway cruising.

rick

67HEAVEN · Poncho Master!

Carl,

The answer is a 5 or 6-speed.

I chose a 5-speed Richmond (no overdrive) and switched out a 4.56:1 diff for a 3.08:1

The top end in 5th is amazing (believe me you don't want to try keeping up), and that crazy 1st gear (3.28) makes me happy in my knees. wink

Here's a little comparison I worked out before making my decision....

Astro Jet · Poncho Master!

For what it is worth, my 70 El Camino 396 SS has the M-20 3.31 combo from the factory and it runs just fine. I agree though, with an M-21, even with a light car like your Ventura Carl, I would go with at least 3.31 gears.

gparis7 · Canadian Poncho Superstar!

In my 68 Impala about 15 years ago, I ran a mild 454 with Muncie M21 and 3.31 Posi with 27" tire. The combo did not work for acceleration or drivability. The 67 Chevelle SS I had ran 396/350 modified motor with M21 and low rear gear around 4.10s. It had quick acceleration but couldn't be driven on the highway.

427carl · A Poncho Legend!

gparis7 wrote:

In my 68 Impala about 15 years ago, I ran a mild 454 with Muncie M21 and 3.31 Posi with 27" tire. The combo did not work for acceleration or drivability. The 67 Chevelle SS I had ran 396/350 modified motor with M21 and low rear gear around 4.10s. It had quick acceleration but couldn't be driven on the highway.

I am looking,to put the Muncie,in the big car. I guess the M20 is the way to go..

67BBSD · Canadian Poncho Superstar!

yes M20 is the way to go not to mention they are more plentiful and cheaper-I have one !

2drpost · Uber Guru

my bel air...M20 1st 2.52 x rear 3.73=9.400 aww

427carl · A Poncho Legend!

69 belair wrote:

my bel air...M20 1st 2.52 x rear 3.73=9.400

and you said you would go 3.55 next time?

427carl · A Poncho Legend!

67BBSD wrote:

yes M20 is the way to go not to mention they are more plentiful and cheaper-I have one !

I was asking a while ago I am interested

67BBSD · Canadian Poncho Superstar!

427carl wrote:

67BBSD wrote:

yes M20 is the way to go not to mention they are more plentiful and cheaper-I have one !

I was asking a while ago I am interested

I know-just given ya a rough time, trade for a house in the Clinton area !

67HEAVEN · Poncho Master!

Carl,

I forgot to point out the obvious advantage of that extra gear. First gear in the Richmond provides 10.10 overall with my 3.08:1 diff. That is considerably better than the 7.76 from the M-20 (with 3.08) or even the 9.32 (with 3.70 diff.)!!!

It's freaky to think of what first gear would be like if I swapped in a 3.70 diff with the Richmond.

Note: Some diff ratios are slightly different with Corvettes - 3.70 rather than 3.73, etc.

65sssd · Poncho Master!

I had a m-21 with 4.11's in my hard top and it was a bugger. I went to a M-20 with 4.11's and it's crazy to 4th gear. I don't have to ride clutch and I still get 15 miles to the gallon. I run a small block but with a m-20 you don't have to modify linkages or tunnel humps. I figure you should have at least two cars, one scarey, and one for good gas milage. My rag is the cruiser, 21 on the highway at 70MPH. Powerglide slip and slide!!

rebelrouser · Poncho Master!

I put a ST-10 w/3:42 first gear cast case along with 3:08's in my "Chief.The ST-10's have a larger gear ratio range.I once had 11 ST-10"s and all of them had a different gear ratio.They were available in either cast or aluminum.0 floor modification's.The Muncie is identical to the T-10 other than the side cover.The Muncie has 7 bolts and the Borg Warner has 9.If anyone wants more info on how to identify what gear ratio a T-10 may have feel free to ask.I have LOTS of information on 4spd stuff.Remember"Real Cars Have Three Pedals".The 'Chief will soon be on the road around here in Cowtown.Can't wait!!!!!

-- Edited by rebelrouser at 20:21, 2009-03-07

427carl · A Poncho Legend!

gparis7 · Canadian Poncho Superstar!

I have two M21s with the early spline count and one M20 with the later spline. Looks like I'll be converting the yoke for the M20 if I ever decide to 4 speed one of my early cars because I won't want to use the M21/deeper low rear gears combo.

87 player bird · Poncho Master!

iHAVE 3:42 IN MY Z AND IT PURRS LIKE A KITTEN.

427carl · A Poncho Legend!

87 player bird wrote:

iHAVE 3:42 IN MY Z AND IT PURRS LIKE A KITTEN.

I have a Rat not a kitten lol lol

davelacourse · Poncho Master!

427carl wrote:

Is anyone running a close ratio Muncie with highway gears?? (3.08)

That's what I had in my 1967 Corvette, 390 HP 427 w/ factory A/C and leather interior, and it was sloooooow off the line (not important to me in a cruising car like that one was) but the big block torque was fat down low (hydraulic lifters and oval port heads, definietley not a hot rod) so it was smooooooooth. Cruising at 80 mph that 427 was just loafing, down to 3rd for rocket-ship passing, and it did 140 mph on the open road without strain.

Also could easily keep the rpm's down low so those great factory side pipes didn't draw too much attention from the cops (but that big block purr sure sounded nice).

I'd do it again for a cruiser, but not for a higher-strung hot rod.

Here's the plates I had on my 67 roadster:

Minnesota Loaded.JPG

Dave

-- Edited by davelacourse on Sunday 22nd of March 2009 02:56:25 PM