Flywheel info needed - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Rdrdave · 02-21-2005, 01:31 PM

What is the tooth count 153/168, flywheel size 12"/14", and clutch size 10.5/11/12 or a '68 lwb? It currently has a 3 speed in it witha 307.
I'm trying to setup an engine and tranny for my 68. I bought a M21 and bellhousing setup. The PO said it was on a 350 w/a 10.5 clutch. I ran the numbers on the bellhousing and it comes up as a malibu, nova, chevelle with the small blocks but it also came up with a 427 corvette with 11".
I am trying to figure if there is a difference if the 11" clutch will fit under the bellhousing. If so, does the 68 flywheel come with an 11" clutch?

Any info is greatly appreciated.

72402 · 02-21-2005, 10:27 PM

What's the number on your bellhousing? I'll check it against one I have for an 11" clutch. 307/3 speed setup could have either 10 or 11", I think only heavy duty 4-speeds had 12". I beleive 11 and 12" fit same flywheel. but bolt circle for 10" pressure plate is smaller. This could be wrong, just the way I remember from past experience. Frank

Rdrdave · 02-21-2005, 10:38 PM

The casting # 3840383. I believe my stock flywheel is an 11" as when ordering parts online they show 11" clutch setups. I'm just hoping I can keep the 11" or did I buy the wrong bellhousing?

What I really want is to run an 11" but am not sure if it will fit under that bellhousing.

69 longhorn · 02-21-2005, 10:44 PM

If you are running the stock cast bell(starter bolts on the bell with 3 bolts)....you have a 14" diam wheel (measured at the OD of the starter ring gear). you can have a 10 1/2 " clutch, if fitted originally with a 6. the sb wheel fitted an 11 or12" clutch, & the boltholes for the press plate were to the very outside of the wheel........69L

Rdrdave · 02-21-2005, 10:55 PM

It's a stock 307 in it w/3spd. I guess I have the 11" or 12". DO you think the car M21 bell will fit over or will it hit the pressure plate?

I do appreciate all of your assistance.

72402 · 02-22-2005, 12:25 AM

Well, the number on mine is 3899621, but that doesn't mean yours isn't also for 11". I don't know what mine came out of, I got it with a saginaw 4-speed and 11" clutch setup. Why not just use your stock cast iron bellhousing? They'll fit even the 12". Unless you just want to get away from the motor mounts on the bellhousing and use the rear crossmember setup.

**passthebuck** · 02-22-2005, 12:43 AM

My 67 came with an 11" clutch & the clutch dude I went to told me that if I had an 11" I could stay with an 11 or upgrade to a 12" for 15 bucks more. it is a 168t flywheel. I also have a flywheel lying around for a 10" & my clutch dude said that you cant upgrade that flywheel due to a smaller bolt pattern for the pressure plate, it is however, the same tooth count as the 11" one I have. I hope this helps....

Rdrdave · 02-22-2005, 02:12 AM

Quote:

Originally Posted by passthebuck

My 67 came with an 11" clutch & the clutch dude I went to told me that if I had an 11" I could stay with an 11 or upgrade to a 12" for 15 bucks more. it is a 168t flywheel. I also have a flywheel lying around for a 10" & my clutch dude said that you cant upgrade that flywheel due to a smaller bolt pattern for the pressure plate, it is however, the same tooth count as the 11" one I have. I hope this helps....

Apparently, word has it, the center hole is a 5" hole while the M21 is a 4.5 hole. Won't work correctly.

72402 · 02-22-2005, 11:00 AM

I have an M21 in my street rod with a 10" clutch. The difference is in the position of the mounting holes for the pressure plate.

69 longhorn · 02-22-2005, 01:54 PM

Quote:

Originally Posted by Rdrdave

Apparently, word has it, the center hole is a 5" hole while the M21 is a 4.5 hole. Won't work correctly.

if you use a 67 or older bell, it will have the propper centerhole for the M 21(4.683). the 68 up trucks went to a 5.126 hole.......69L

Rdrdave · 03-20-2005, 09:05 PM

Well, I solved my problem. We had a swap meet in Pleasanton, CA and I was selling some wheels and stuff. Well the guy two stalls over was asleep, 4:00 AM, he had a 3899621 bellhousing for sale. I jumped on it the moment he woke up. Problem solved! Now to get the auto crossmember, poly mount, and the 268 cam!

02-21-2005, 01:31 PM	#1
Rdrdave Broke and still trying Join Date: Apr 2003 Location: Alameda, CA Posts: 562	Flywheel info needed What is the tooth count 153/168, flywheel size 12"/14", and clutch size 10.5/11/12 or a '68 lwb? It currently has a 3 speed in it witha 307. I'm trying to setup an engine and tranny for my 68. I bought a M21 and bellhousing setup. The PO said it was on a 350 w/a 10.5 clutch. I ran the numbers on the bellhousing and it comes up as a malibu, nova, chevelle with the small blocks but it also came up with a 427 corvette with 11". I am trying to figure if there is a difference if the 11" clutch will fit under the bellhousing. If so, does the 68 flywheel come with an 11" clutch? Any info is greatly appreciated.

02-21-2005, 10:44 PM	#4
69 longhorn Registered User Join Date: Aug 2001 Location: rock island,il,usa Posts: 5,382	If you are running the stock cast bell(starter bolts on the bell with 3 bolts)....you have a 14" diam wheel (measured at the OD of the starter ring gear). you can have a 10 1/2 " clutch, if fitted originally with a 6. the sb wheel fitted an 11 or12" clutch, & the boltholes for the press plate were to the very outside of the wheel........69L __________________ http://community.webshots.com/user/hotrodhorn

02-22-2005, 12:25 AM	#6
72402 Registered User Join Date: Nov 2004 Location: Cameron, Oklahoma Posts: 199	Bellhousing Well, the number on mine is 3899621, but that doesn't mean yours isn't also for 11". I don't know what mine came out of, I got it with a saginaw 4-speed and 11" clutch setup. Why not just use your stock cast iron bellhousing? They'll fit even the 12". Unless you just want to get away from the motor mounts on the bellhousing and use the rear crossmember setup.

02-22-2005, 12:43 AM	#7
passthebuck Sisyphus was my mentor! Join Date: Sep 2002 Location: Carleton Place, Ontario CANADA Posts: 984	My 67 came with an 11" clutch & the clutch dude I went to told me that if I had an 11" I could stay with an 11 or upgrade to a 12" for 15 bucks more. it is a 168t flywheel. I also have a flywheel lying around for a 10" & my clutch dude said that you cant upgrade that flywheel due to a smaller bolt pattern for the pressure plate, it is however, the same tooth count as the 11" one I have. I hope this helps.... __________________ passthebuck #5642 -TWO 1967 GMC 910's. One with L6/3-on-the tree and the other with 355 w/435hp & a 700r4. -a 2013 Honda Civic as my "sensible" car

02-21-2005, 10:27 PM	#2
72402 Registered User Join Date: Nov 2004 Location: Cameron, Oklahoma Posts: 199	What's the number on your bellhousing? I'll check it against one I have for an 11" clutch. 307/3 speed setup could have either 10 or 11", I think only heavy duty 4-speeds had 12". I beleive 11 and 12" fit same flywheel. but bolt circle for 10" pressure plate is smaller. This could be wrong, just the way I remember from past experience. Frank

02-21-2005, 10:38 PM	#3
Rdrdave Broke and still trying Join Date: Apr 2003 Location: Alameda, CA Posts: 562	The casting # 3840383. I believe my stock flywheel is an 11" as when ordering parts online they show 11" clutch setups. I'm just hoping I can keep the 11" or did I buy the wrong bellhousing? What I really want is to run an 11" but am not sure if it will fit under that bellhousing.

02-21-2005, 10:55 PM	#5
Rdrdave Broke and still trying Join Date: Apr 2003 Location: Alameda, CA Posts: 562	It's a stock 307 in it w/3spd. I guess I have the 11" or 12". DO you think the car M21 bell will fit over or will it hit the pressure plate? I do appreciate all of your assistance.

02-22-2005, 11:00 AM	#9
72402 Registered User Join Date: Nov 2004 Location: Cameron, Oklahoma Posts: 199	I have an M21 in my street rod with a 10" clutch. The difference is in the position of the mounting holes for the pressure plate.

03-20-2005, 09:05 PM	#11
Rdrdave Broke and still trying Join Date: Apr 2003 Location: Alameda, CA Posts: 562	Well, I solved my problem. We had a swap meet in Pleasanton, CA and I was selling some wheels and stuff. Well the guy two stalls over was asleep, 4:00 AM, he had a 3899621 bellhousing for sale. I jumped on it the moment he woke up. Problem solved! Now to get the auto crossmember, poly mount, and the 268 cam!



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