1970 Corvette LS-5 Question
Thread Starter
6th Gear
Joined: Feb 2007
Posts: 6
Likes: 0
1970 Corvette LS-5 Question
Hi,
I'm a new member and currently own a 70 LS-5 coupe and a 72 L48 convertible. I have a question about my LS-5. I recently pulled out my M20 to install a new clutch kit and inspected the flywheel and it has a casting number of 3963538 with a date code of K5 9. I have no idea what vehicle this flywheel came out of. Can anyone cross this number to another chevy vehicle? I believe the correct flywheel for my setup should have a casting number of 3973457. Any help would be greatly appreciated.
I'm a new member and currently own a 70 LS-5 coupe and a 72 L48 convertible. I have a question about my LS-5. I recently pulled out my M20 to install a new clutch kit and inspected the flywheel and it has a casting number of 3963538 with a date code of K5 9. I have no idea what vehicle this flywheel came out of. Can anyone cross this number to another chevy vehicle? I believe the correct flywheel for my setup should have a casting number of 3973457. Any help would be greatly appreciated.
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
This is a "NCRS" type question... there are a few NCRS types on here, but not the majority. Hopefully somebody will chime in, but don't feel slighted if they don't.... try the NCRS forum if that happpens.
I just thumbed through my NCRS 1953-1972 Pocket Spec Guide but found nothing on flywheels.
I just thumbed through my NCRS 1953-1972 Pocket Spec Guide but found nothing on flywheels.
Instructor
Joined: Sep 2005
Posts: 180
Likes: 1
no ncrs cannot look at the flyweel as it is not exposed, if it was from a 69 it would be a 427 internally balanced one and would shake like crazy in a 454 externally balanced engine, could have been cast in 79,89, or 99. Ask joe lucia at the ncrs website, he is the man and will be 100% correct everytime!!
Thread Starter
6th Gear
Joined: Feb 2007
Posts: 6
Likes: 0
Good info....That's a good point about the timeframe on when it was cast. I didn't think about it being cast 79 thru 99. I believe the flywheel I currently have is too thick as I do not have any free play in the clutch fork/bearing. It is hard up against the pressure plate. I did find another flywheel listing on Ebay with a casting number that crosses to the correct part # for a 70 LS5. I was trying to avoid spend another $300 bucks if I could research and determine that the one I have will still work. I did research the number on the bellhousing and it seems to be correct for my year. Thanks again for all the feedback.
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Le Mans Master
Joined: Oct 2006
Posts: 7,123
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Good info....That's a good point about the timeframe on when it was cast. I didn't think about it being cast 79 thru 99. I believe the flywheel I currently have is too thick as I do not have any free play in the clutch fork/bearing. It is hard up against the pressure plate. I did find another flywheel listing on Ebay with a casting number that crosses to the correct part # for a 70 LS5. I was trying to avoid spend another $300 bucks if I could research and determine that the one I have will still work. I did research the number on the bellhousing and it seems to be correct for my year. Thanks again for all the feedback.
If you can't adjust the clutch I would suspect that someone has changed the pivot ball or the fork is bent. Most BB flywheels are something like 3/4 thick. How old is that clutch? As a clutch wears, the fingers on the pressure plate move toward the t/o bearing (rear of the car).
Racer
Joined: Dec 2006
Posts: 417
Likes: 40
From: Swansea IL
Clutch Pivot Ball
Tim AT is correct in that there were three pivot ***** that installed in the bellhousing. The height of all theree is different. Some aftermarket parts suppliers even made one adjustable for height.
Can' imagine a flywheel that is way too think, but what the heck to I know. I would research the pivot ball, that would be my number one focus.
RGDS
Bob
Can' imagine a flywheel that is way too think, but what the heck to I know. I would research the pivot ball, that would be my number one focus.
RGDS
Bob
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
What kind of clutch are you installing? Centerforce?
This might help...
http://members3.clubphoto.com/glenn2...99/guest.phtml
also includes this pic:
This might help...
http://members3.clubphoto.com/glenn2...99/guest.phtml
also includes this pic:
Le Mans Master
Joined: May 2003
Posts: 8,876
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
If you do a Google search on the part numbers-One persons states it might be off a 400 small block-yet another claims it's correct on a 2 owner 70 LS6 Chevelle for sale....http://cgi.ebay.com/ebaymotors/ws/eB...m=130043460578 If he's correct- your Flywheel might have been cast in 1969...
Anyway- I have a 3973457 Flywheel from a December 70 LS-5 Corvette engine and it's dated H10 -or August 1st 1970. If you need pics or dimensions -let me know. And if interested I'll sell it a lot less then $300...
Richard
Anyway- I have a 3973457 Flywheel from a December 70 LS-5 Corvette engine and it's dated H10 -or August 1st 1970. If you need pics or dimensions -let me know. And if interested I'll sell it a lot less then $300...
Richard
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
I may be able to look up the old part number, but not the casting number. I have a set of GM Parts Catalogs given to me by a Chevy Dealer.
When I was active in my business, they were so sick of me pestering them for Corvette parts (wholesale) that they gave me a set of catalogs and told me to look it up myself.
The catch was, anything I ordered, I had to keep. So it was up to me not to make any mistakes.... I learned to use the catalogs pretty accurately.
When I was active in my business, they were so sick of me pestering them for Corvette parts (wholesale) that they gave me a set of catalogs and told me to look it up myself.
The catch was, anything I ordered, I had to keep. So it was up to me not to make any mistakes.... I learned to use the catalogs pretty accurately.
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Section 0.666 (uh oh) of the GM Parts Catalog lists only one flywheel for the automatic (343738 $75.75) and only one for the manual (3993827 $111.00) for 70-74 with 454.
Those 2 numbers are unique to the 454 and are not listed for any other Corvette big blocks.
Nice prices... too bad they're from 1982.
Those 2 numbers are unique to the 454 and are not listed for any other Corvette big blocks.
Nice prices... too bad they're from 1982.
