Pics of my new Muncie 4 speed in my '68 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jefe · 12-10-2002, 01:22 AM

For those of you that helped me out or wanted to see the M20 in my '68...here ya go! Thanks again!! (getting the hang of quick-shifting that bad-boy...man thats fun!! hehe)

Jefe · 12-10-2002, 01:23 AM

2

Jefe · 12-10-2002, 01:24 AM

3

67cst · 12-10-2002, 03:35 AM

sweet man, tme to go chirp some tires

chevypete396 · 12-10-2002, 07:08 AM

I'm very intrested in this swap. I know very little about the M20

Tell me about it....

What tranny did you swap from?

Whats first gear like?

How does the tranny shift? Sincro in all gears?

Is the 4th gear 1:1?

How do you rate that tranny for your truck?

Any info greatly appreciated. Thanx... Pete

Mike C · 12-10-2002, 09:07 AM

Your installation looks nice. To answer some of Chevypete's Q's, there are two common versions of the aluminum cased Muncie car transmission. The M20 and M21 note that GM called the cast iron truck 4 speed an M20 as well. The car M20 is a "wide" ratio with a 2.52 first gear. Compare this to the stock 3 speeds 3.5 first gear and getting moving will be hard with less than 3.73 gears. The M21 holds the record for the closest ratio production 4 speed ever made with a 2.20 first gear. It was only available with 3.73 or higher gears and IMO is not suitable for a heavy vehicle and at minimum one with 3.73 or higher numerically gears. All Muncies are 1:1 top gear. There were some oddball Saginaw 4 speeds where top gear was an OD. (Actually, they flip-flopped the three-four shift arm and when you shifted into 3rd it was really 1:1 then when you shifted into "4th" it was actually 3rd and the had installed an overdrive gear set instead of the standard underdrive 3rd gear.) For a "street truck" where communting and performance are of topmost importance, the wide ratio Muncie and 3.73 is a reasonable choice. For any heavy towing, the 3 speed is probably the better choice or one of the cast iron truck 4 speeds.

crazy longhorn · 12-10-2002, 09:14 AM

Very clean installation, & they are a very durable gearbox! I ran an M21 in a 71 for about 100,000 miles & loved it......it outlasted the truck

imaindianoutlaw · 12-10-2002, 01:17 PM

crossmember?

crazy longhorn · 12-10-2002, 01:42 PM

The stick trucks had a bell crossmember,& nothing under the trans. You can also use the auto crossmember if you are converting from auto to stick......the complete set up is the same lenght as a 350 hydro/ short tail.....

Cheyenne Super · 12-10-2002, 09:15 PM

is your engine in the I-6 or std. v-8 position?
your pics will be very helpful in my engine positioning and tranny fitment.
thanks

chevypete396 · 12-11-2002, 10:00 AM

Thank you, Mike... Pete.

Jefe · 12-11-2002, 03:37 PM

Engine is in standard v8 position.

GMC JUNKIE TOO · 12-11-2002, 11:19 PM

Call me dumb but what is the diffrence between the 6&8 position?I replaced my 6 with an 8 and had no problems. I learn sompthing new evreyday

GMC JUNKIE TOO · 12-12-2002, 01:51 PM

Is the eingin placed lower when in the 8 position?

Tyler_69C10 · 12-12-2002, 02:54 PM

I think the engine is placed farther back in the 6cyl position, and farther forward in the 8 position. I think a lot of people sometimes put their 8cyl motors in the 6cyl positionf or better weight distribution.

I could be wrong, though.

crazy longhorn · 12-12-2002, 03:35 PM

To run a sb V8 in i 6 position gives right at 3 1/2" of setback, & as far as height, if there is any difference its not much......I havent had any problems with the fan fitting in the shroud

GMC JUNKIE TOO · 12-12-2002, 04:57 PM

To run in the 8 position what do I need to replace, engine mounts, trans crosmember? Mine is kinda close to the firewall, the MSD distributor barely fit in.

crazy longhorn · 12-12-2002, 08:25 PM

To run in the V8 position, you need to replace the eng mount stands, & slide the crossmember ahead(assuming auto trans). If you have a 3spd stick, with the bell crossmember, that will need to be changed, or removed & just run an auto crossmember under the trans(this wont work with the truck 4spd,as there is no provision for a mount at the rear of the trans). You will also find the D shaft to be too short, as will the exhaust! Up front, you could find the later style long water pump set up(mine is done that way)......& could cause clearance/shroud issues when moved foward. .....

chevypete396 · 12-13-2002, 03:44 AM

Tyler_69C10,

I think your right on the money: the farther back your engine is the better the weight distribution. When building a "kit car" the builder trys to get the engine as far back as possible. Ive seen some radical set backs but it makes life tough when you want to do stuff to the engine. I can barely take the valve covers off my 454 and "tall" ones are out of the question because its so close to the firewall... Pete.

GMC JUNKIE TOO · 12-14-2002, 08:09 PM

Thanks for the info guys. Im not going to mess with it I can get to evreything allright.

12-10-2002, 01:22 AM	#1
Jefe Registered User Join Date: Jul 2000 Location: Chandler, Arizona, USA Posts: 299	Pics of my new Muncie 4 speed in my '68 For those of you that helped me out or wanted to see the M20 in my '68...here ya go! Thanks again!! (getting the hang of quick-shifting that bad-boy...man thats fun!! hehe) Attached Images

12-10-2002, 01:23 AM	#2
Jefe Registered User Join Date: Jul 2000 Location: Chandler, Arizona, USA Posts: 299	2 Attached Images

12-10-2002, 01:24 AM	#3
Jefe Registered User Join Date: Jul 2000 Location: Chandler, Arizona, USA Posts: 299	3 Attached Images

12-10-2002, 03:35 AM	#4
67cst i love summertime Join Date: Jul 2002 Location: Kelowna BC Posts: 4,302	sweet man, tme to go chirp some tires __________________ 1967 shortbox stepside Chevy, 365 hp 327, th400. GLOVE BOX LIGHTS FORSALE, click link for info http://67-72chevytrucks.com/vboard/s...d.php?t=273724

12-10-2002, 07:08 AM	#5
chevypete396 Registered User Join Date: Mar 2002 Location: Fernley, Nevada, USA Posts: 540	Questions.... I'm very intrested in this swap. I know very little about the M20 Tell me about it.... What tranny did you swap from? Whats first gear like? How does the tranny shift? Sincro in all gears? Is the 4th gear 1:1? How do you rate that tranny for your truck? Any info greatly appreciated. Thanx... Pete __________________ 1968 Chevy - 3/4 Ton - 4X4 - Longbed - 383ci - TH350 - NP205 Building the motor, painting the engine bay, rewireing everything... (775)-527-1199 / ryanspeterson@msn.com

12-10-2002, 09:07 AM	#6
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,727	Your installation looks nice. To answer some of Chevypete's Q's, there are two common versions of the aluminum cased Muncie car transmission. The M20 and M21 note that GM called the cast iron truck 4 speed an M20 as well. The car M20 is a "wide" ratio with a 2.52 first gear. Compare this to the stock 3 speeds 3.5 first gear and getting moving will be hard with less than 3.73 gears. The M21 holds the record for the closest ratio production 4 speed ever made with a 2.20 first gear. It was only available with 3.73 or higher gears and IMO is not suitable for a heavy vehicle and at minimum one with 3.73 or higher numerically gears. All Muncies are 1:1 top gear. There were some oddball Saginaw 4 speeds where top gear was an OD. (Actually, they flip-flopped the three-four shift arm and when you shifted into 3rd it was really 1:1 then when you shifted into "4th" it was actually 3rd and the had installed an overdrive gear set instead of the standard underdrive 3rd gear.) For a "street truck" where communting and performance are of topmost importance, the wide ratio Muncie and 3.73 is a reasonable choice. For any heavy towing, the 3 speed is probably the better choice or one of the cast iron truck 4 speeds. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax Last edited by Mike C; 12-10-2002 at 10:41 AM.

12-10-2002, 09:14 AM	#7
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	Very clean installation, & they are a very durable gearbox! I ran an M21 in a 71 for about 100,000 miles & loved it......it outlasted the truck __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

12-10-2002, 01:17 PM	#8
imaindianoutlaw GMC SHORT FLEET F/S Join Date: Jun 2000 Location: SOUTH WILLIAMSPORT PENNSYLVANNIA Posts: 2,117	crossmember? __________________ CHARLES WADE HEIN HVACR FOREMAN. LEWISBURG U.S.P.

12-10-2002, 01:42 PM	#9
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	The stick trucks had a bell crossmember,& nothing under the trans. You can also use the auto crossmember if you are converting from auto to stick......the complete set up is the same lenght as a 350 hydro/ short tail..... __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

12-10-2002, 09:15 PM	#10
Cheyenne Super Registered User Join Date: Mar 2002 Location: Efland, NC Posts: 303	engine location is your engine in the I-6 or std. v-8 position? your pics will be very helpful in my engine positioning and tranny fitment. thanks __________________ 1971 Cheyenne Super Soon to be converted to '68 front clip. Efland, NC

12-11-2002, 10:00 AM	#11
chevypete396 Registered User Join Date: Mar 2002 Location: Fernley, Nevada, USA Posts: 540	Thank you, Mike... Pete. __________________ 1968 Chevy - 3/4 Ton - 4X4 - Longbed - 383ci - TH350 - NP205 Building the motor, painting the engine bay, rewireing everything... (775)-527-1199 / ryanspeterson@msn.com

12-11-2002, 03:37 PM	#12
Jefe Registered User Join Date: Jul 2000 Location: Chandler, Arizona, USA Posts: 299	Engine is in standard v8 position. Attached Images

12-11-2002, 11:19 PM	#13
GMC JUNKIE TOO THE QUICKER FIXERUPER Join Date: Jul 2002 Location: Ok Posts: 615	Call me dumb but what is the diffrence between the 6&8 position?I replaced my 6 with an 8 and had no problems. I learn sompthing new evreyday

12-12-2002, 01:51 PM	#14
GMC JUNKIE TOO THE QUICKER FIXERUPER Join Date: Jul 2002 Location: Ok Posts: 615	Is the eingin placed lower when in the 8 position?

12-12-2002, 02:54 PM	#15
Tyler_69C10 Registered User Join Date: May 2002 Location: Sidney, BC, Canada Posts: 63	I think the engine is placed farther back in the 6cyl position, and farther forward in the 8 position. I think a lot of people sometimes put their 8cyl motors in the 6cyl positionf or better weight distribution. I could be wrong, though. __________________ 1969 Chevy C/10 LWB A great work truck!



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12-12-2002, 03:35 PM	#16
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	To run a sb V8 in i 6 position gives right at 3 1/2" of setback, & as far as height, if there is any difference its not much......I havent had any problems with the fan fitting in the shroud __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

12-12-2002, 04:57 PM	#17
GMC JUNKIE TOO THE QUICKER FIXERUPER Join Date: Jul 2002 Location: Ok Posts: 615	To run in the 8 position what do I need to replace, engine mounts, trans crosmember? Mine is kinda close to the firewall, the MSD distributor barely fit in.

12-12-2002, 08:25 PM	#18
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	To run in the V8 position, you need to replace the eng mount stands, & slide the crossmember ahead(assuming auto trans). If you have a 3spd stick, with the bell crossmember, that will need to be changed, or removed & just run an auto crossmember under the trans(this wont work with the truck 4spd,as there is no provision for a mount at the rear of the trans). You will also find the D shaft to be too short, as will the exhaust! Up front, you could find the later style long water pump set up(mine is done that way)......& could cause clearance/shroud issues when moved foward. ..... __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

12-13-2002, 03:44 AM	#19
chevypete396 Registered User Join Date: Mar 2002 Location: Fernley, Nevada, USA Posts: 540	Tyler_69C10, I think your right on the money: the farther back your engine is the better the weight distribution. When building a "kit car" the builder trys to get the engine as far back as possible. Ive seen some radical set backs but it makes life tough when you want to do stuff to the engine. I can barely take the valve covers off my 454 and "tall" ones are out of the question because its so close to the firewall... Pete. __________________ 1968 Chevy - 3/4 Ton - 4X4 - Longbed - 383ci - TH350 - NP205 Building the motor, painting the engine bay, rewireing everything... (775)-527-1199 / ryanspeterson@msn.com

12-14-2002, 08:09 PM	#20
GMC JUNKIE TOO THE QUICKER FIXERUPER Join Date: Jul 2002 Location: Ok Posts: 615	Thanks for the info guys. Im not going to mess with it I can get to evreything allright.

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