Rear end 3.08 swap to 3.70

[Jim C.]

After my national top flight a couple of years ago I decided to have some 1960s style fun. Just finished putting the 3.70 in with the existing wide ratio tranny, radials, hurst shifter with the 63 handle, k and n air filter, Bilsteins, etc.
BTW it's a 63 SHP. WOW! 6000 RPM and all

[Mike M.]

Re: Rear end 3.08 swap to 3.70

nothin like 4.56 gears for chuckles. mike

[Duke W.]

Re: Rear end 3.08 swap to 3.70

k and n air filter,

Geez, ditch the K&N filter unless you want to dirt hone the bores.

Look at the last Corvette Restorer for the tests of the Special 300 HP engine with and without the air cleaner. K&N doesn't flow better or make more power than a quality cellulose element of the same size - just more bore wear. This has been discussed extensively in the archives including a link to filter flow and power tests.

I think the NAPA 2070 is a decent fit for the '63 air cleaner housing.

Duke

[Jim T.]

Re: Rear end 3.08 swap to 3.70

I have never used a K&N filter on my Corvettes and never will.

[Peter M.]

Re: Rear end 3.08 swap to 3.70

Duke - do you know if Napa has something for 71 LT-1? Thanks Pete

[Duke W.]

Re: Rear end 3.08 swap to 3.70

No, but I'm sure if you got to www.napaonline.com and search the catalog you will find a functionally correct OE replacement filter.

Duke

[Steven B.]

Re: Rear end 3.08 swap to 3.70

Jim, since your tires are probably not as tall as the original 6.70's your effective ratio will change. As I recall the formula is (new tire diameter/original tire diameter) X diff. ratio (3.7 for you) = your new effective ratio. My '77 came with 3.55's, I changed to 3.90's and installed 45 series tires and ended up with an effective ratio of about 4.10.

To illustrate what Mike said: lower aspect ratio and gearing = .

Steve

[Stephen B.]

Re: Rear end 3.08 swap to 3.70

Good Afternoon
Now you can enjoy your Corvette rather than having another Garage orniment museum piece.Contrary to some opinions on this site I love K&N airfilters and have had NO negative problems with them. I have installed them on my 1966 L79 one owner roadster and my 96 Silverodo. The 66 is the love of my life, and the pickup has 165,000 miles on it and runs like the day I bought it new.
When I calculate actual gear ratios after installing other than stock size tires.I compare the two circumferences and convert that to a percentage. If the replacement tire is smaller in circumference the gear ration will be higher and visa versa.
Two more things you might want to add to your modifications are a monoleaf composite spring and an aluminum flywheel. Bilsteins and compsite springs work great together,and the flywheel will give your car more zing. I've run aluminum flywheels in several of my Corvettes and loved them with NO side effects NONE.
Stephen Barrett (21558)