4 speed manual vs th350

[mebe007]

Ok do the muncie I listed is a close ratio? It's a 2 hour drive. And the t10 I listed said he will take $500. So I'm s bit lost.


I'll be running 3.42 gears in.the 8.5 I have

 

[Randy_W]

M-20 is wide ratio so 3.42 would be great gears for it, M-21 and M-22 (rock crusher) are the close ratio units. The M-22 was also available in wide ratio versions for high horsepower higher geared or heavier applications.

Model

Gear ratio 1st-4th
M20 Wide 63-65
2.56-1.91-1.48-1.00

M20 Wide 66-74
2.52-1.88-1.46-1.00

M21 Close 63-74
2.20-1.64-1.28-1.00

M22 Close
2.20-1.64-1.28-1.00

M22 Wide
2.52-1.88-1.46-1.00

 

[mebe007]

How's the price on it?

 

[Bonnewagon]

Randy W is right, M-20 is wide ratio, my mistake. 😳 I was thinking T-10's. But 2:52 X 3:42 gives you an 8.61 overall first gear ratio, not very good for the street, with 10 to 1 being about perfect, but probably OK for racing. Even 2:52 X 3:73 only gives you 9.33 overall. 2:52 X 4:11 gets you 10.3. (Think 1960's) That is why the factories went to the really low first gear ST-10's with up to 3:42 first gears. I have one of those in my 77' TA with a 3:08 rear and that works out to 10.5 overall ratio. Taking off from a dead stop is a breeze, just slip your foot off the clutch and you are rolling, no riding the clutch at all. Plus the 3:08 rear gears give me a sweet highway cruise rpm too. This is why I love my Saginaws, they come with 3:11 and 3:50 first gears which work great with granny gears out back. Use the calculators at http://www.wallaceracing.com and throw some combinations in to see what you really want to do.

 

[mebe007]

I'm confused about the ideal #. Also isn't the stock th350 a 2.52? It's a street car but a hot street car. Maybe the track a few times a year

 

[Bonnewagon]

Well, you can't compare an automatic to a manual on takeoff from a dead stop. The automatic is always engaged. At a dead stop, there is a fluid connection that slips so the motor does not stall. You just hit the gas and go. The manual is a hard connection that needs to be finessed so as not to stall the motor. You must coordinate throttle/clutch with a wee bit of clutch slippage so the car moves easily without burning up the clutch disc. A high overall ratio makes it infinitely easier to get rolling from a dead stop. A low overall ratio makes it harder to get the car rolling without slipping the clutch a LOT. A really bad ratio is like trying to start off in second or third gear. Torture! This is hard on the clutch disc as well as the rest of the drive-train. Of course a tough street car or racing car isn't worried about this, you just rev the motor, dump the clutch, and let the horsepower do the talking as you lay rubber. But this gets very tedious on the street especially in traffic. Ever hear a big truck with bad gearing laboring to get going at a light? Now how about a little 4 banger stick shift econo-box that gets going seemingly without any effort at all? Gearing, it's all in the gearing. Most guys who drive a stick every day will agree on the 10 to 1 overall ratio as the ideal set up. You must make a decision what you are willing to put up with driving this car. As for me, when I get stuck in stop-and-go traffic, I love being able to just keep it in first and work the clutch in and out to creep along.

 

[mebe007]

well essentially its what i like to call a weekend warrior. itl just be pulled out on the weekends to shows and stuff like that. by no means a commuter. i may take it to the track but it probably wouldnt see more than 10 passes a year. i just want to make sure i have the so to speak perfect combo.

 

[Randy_W]

When you figure these overall ratios don't forget tire height a 3.08 with 25" tire like a 275/40/17, is similar to a 3.42 with a 28" tire. I've run a lot of combos on 8:1 range first gear and with a little torque from the engine seems fine. My '68 Firebird 400 Ram Air II had 3.36 gears and a 4 speed wide ratio Muncie, with ignition work, rejetting and some other minor tweaks ran 13.30's and you could just about let the clutch out with almost no throttle and it would pull away like a freight train. Now if it was a 327 Camaro it would have like a better first gear effective ratio.

 

[mebe007]

well the motor i am building is using this cam and is a .060" over small block w/ flat top 2 valve reliefs, 64cc 195cc aluminum heads, 10.5:1 compression, ported and 1206 matched performer rpm. going to ditch the demon 650 for a 750 or fuel injection. ignition is an msd digital ecurve w/ msd 6a and msd blaster ss coil w/ msd super conductor wires.

Howards, Hydraulic Roller Cam, Chev SB 262-400, Retro-Fit
Chev SB 262-400 1955-1998
Advertised Duration: 294/302
Duration @ .050": 234/242
Valve Lift w/1.50 Rockers: .533/.548
Lobe Separation Angle: 112
Intake Centerline: 108
Valve Lash: Hyd./Hyd.
2400-6000. Lopey idle, hot street & bracket racing. 10.0:1-up CR advised. 2800+ stall


she should make some decent power

as far as tires she is currently sitting on 215/65/r15 (26") and i was really wanting a 275/60r15 but that doesnt seem ideal to run a 28" tire with 3.42 so i was thinking 275/50r15 or 255/60r15

 

[Bonnewagon]

Yeah, with that cam you'll be riding the clutch anyway so you should be fine. Don't forget too that those 60's 70's cars usually had little E or F-78 14" tires, so that effectively raised the gear ratios too. My 68' Firebird 400 had 3:55's and it was a stump puller no matter what trans I put in, but it spun too high for my liking at highway speeds. A high revving Chevy may have been at home there, but a long stroke Pontiac was pushing it. But if it's a weekend fun car, it really isn't an issue. I'd say go for it, and adjust your rear as needed, if at all. Another thing, the Muncie series was the replacement for the weak early T-10's, but then the much stronger Super T-10's replaced the Muncie. I had a friend who regularly twisted Muncie mainshafts as well as driveshafts because his suspension was so solid (67' Firebird factory double traction bars added to 79' TA disc rear) with an "S" cammed 400.