Saginaws came with 2.54 (no or one groove), 3.11 (2 grooves) and 3.49 (3 grooves). There's no such thing as a close ratio Saginaw (2.20). As mentioned above a 3 groove (3.49 1st gear) would work with a 3.78, 2.73 or even a 2.56 rear, 4th gear would be almost like overdrive. To me, the best combination would 3.23 or 3.42 rear with a 2.54 1st gear. You can move the speedometer gear from the 3 speed to the 4 speed and check it with a GPS to see if it's right.
Ok it’s a very short 1 st and around town 3rd gear is at 3k doing (as Speedo shows 40). I’m thinking it has 3.23 gears. I can leave in 2nd gear like first gear all day. 1st it will rev to 5k very quick and pull well..chirp 2nd and so on. I’m going to wait to do rear end after I do intake, carb, headers, Cam and some worked and milled iron heads. Either leaving this ratio or going 3.08. So Saginaw didn’t make a close ratio? Could this be borg or munci? My mechanic who drives a 66 Big block Vette said his was close ratio four speed and told me felt very similar. I do believe my Speedo gears are off. I’ll gps it to be sure.
