366861N Flywheel

[Larry S.]

Re: 366861N Flywheel

Hi,
In the Corvette Forum many recommend the GM 14085720 flywheel at 15 lbs. Most but not all say this flywheel is only to be used on !965 and up. Why would it not be for a 1964 327/365Hp manual transmission, Also have a 65 fuelie I was thinking about going to the lighter flywheel. What are your thoughts on this and if the 5720 is not for the 64 corvette what part number for a 15 lbs flywheel would work. The L88 part number 3991406 is reported to work on any small block but can't find one.

Thanks

longhornlarry

[Duke W.]

Re: 366861N Flywheel

14085720 is nodular iron, 12.75" OD and designed for a 10.4" clutch, 153T ring gear for internally balanced engines, so it should be a "bolt-iin" for any internally balanced SB that originally used the same flywheel dimensions/tooth count: however, given it's light weight I would be hesitant to install it on a 365 HP engine with less than a 3.70 axle and relatively flat terrain driving conditions. I think this part is essentially the replacement for the early 18 pound L-88 flywheel, 3991406, which was discontinued years ago.

[Joe L.]

Re: 366861N Flywheel

14085720 is nodular iron, 12.75" OD and designed for a 10.4" clutch, 153T ring gear for internally balanced engines, so it should be a "bolt-iin" for any internally balanced SB that originally used the same flywheel dimensions/tooth count: however, given it's light weight I would be hesitant to install it on a 365 HP engine with less than a 3.70 axle and relatively flat terrain driving conditions. I think this part is essentially the replacement for the early 18 pound L-88 flywheel, 3991406, which was discontinued years ago.

Duke------


I would not use the GM #14085720 on any small block. In my opinion, the standard weight flywheel is the way to go for small blocks. The only small block that GM ever used the 12-3/4", 15 lb flywheel was 1970-72 ZR-1. This application was never really intended as a street-use application. Plus, the ZR-1 had 23 more cubic inches than 63-68 small blocks.

The GM #14085720 did replace the GM #3991406. As far as I know, both flywheels are 15 lb. In fact, I don't think there's any significant difference between them.

[Mark H.]

Re: 366861N Flywheel

This must be karma of the best kind. I have been away from cars for several years now. I decided tonight I need to get my priorities reordered and get back to work on my '64. I spent a while remembering how to log in to the site, downloading the new app, etc. When I opened the technical discussion, what do I see 9 posts from the top but a thread I started 6 years ago with a new question posted today. Wonderful! Duke, and Joe, it is great to see you are both still sharing your deep knowledge with the masses.

Duke, I am going to get your cam in my engine and get her running if it kills me!!

Mark

[Duke W.]

Re: 366861N Flywheel

Hi Mark... you've been AWOL for too many years, but we'll forgive you.

I'm looking forward to seeing Dynojet RW performance curves on your Special 300 HP engine with the McCagh Special camshaft. The head flow numbers you sent me are right in the sweet spot.

Duke

[Mark H.]

Re: 366861N Flywheel

I am as well! Time to get to work.