T-10 ratio investigation?

clanofwolves wrote: Rogue: On the drivers side of the case just to the rear of the side cover there is a flat area with numbers and letters stamped . What is stamped there ??????????????? Clanofwolves: 8 2B 62A is the only number/letter sequence I found on the drivers side of the gearbox. Does this help? Rogue: The stamped 8 2B 62A that trans was made in FEB. of 72 . Thanks for the information, it's amazing what you/guys know on this site. I'm assuming then, a 1972 T-10 would have a 2.23:1. Is this a close ratio transmission? Which ratio transmission best works with a mild-build 304?

No assuming about it. a 1972 T-10 will have 2.23. 1st gear will be high, Id run 3.54s with the T-10.   yes its a close ratio.

clanofwolves wrote: Rogue: On the drivers side of the case just to the rear of the side cover there is a flat area with numbers and letters stamped . What is stamped there ??????????????? Clanofwolves: 8 2B 62A is the only number/letter sequence I found on the drivers side of the gearbox. Does this help? Rogue: The stamped 8 2B 62A that trans was made in FEB. of 72 . Clanofwolves: Thanks for the information, it's amazing what you/guys know on this site. I'm assuming then, a 1972 T-10 would have a 2.23:1. Is this a close ratio transmission? Which ratio transmission best works with a mild-build 304? purple72Gremlin: No assuming about it. a 1972 T-10 will have 2.23. 1st gear will be high, Id run 3.54s with the T-10.   yes its a close ratio. Thanks so much guys! It is great to get a clarification on my assumption of the 2.23:1 first gear. Facts are so much nicer than guessing! With the "run 3.54s with the T-10" recommendation in mind, I went out to the garage to check the rear gear ratio -Please let me know if I did the check correctly. OK, after jacking up and supporting the rear axle with stands, I marked the tire and the body along with the end of the proppeler shaft and the nose of the casing. I then turned the wheel one complete turn and counted how many revolutions the driveshaft made and it was just over 3 turns. Does this mean the ratio at the rear end is a 308? If it is, what would you guys recommend?

Probably 3.15 gear. If you have a low compression 304 engine, a 2.23 first gear and 3.15 rear, I would suggest a short duration cam, small 4 barrel, and a dual plane intake.

clanofwolves wrote: Sonic Silver wrote: Probably 3.15 gear. If you have a low compression 304 engine, a 2.23 first gear and 3.15 rear, I would suggest a short duration cam, small 4 barrel, and a dual plane intake. Thanks for the advice; and yes, I'm planning to make the stock 9.1 compression for the rebuild. Can you tell me your thoughts on the advantage of the short duration cam and dual plane intake? Thanks again! Dave

With a 2.23 first gear and 3.15 rear, you don't have much gear multiplication (2.23 x 3.15 = 7.02). Most standard 350 cu. inch Corvettes back in the late 60's-early 70's had a wide ratio trans with about a 2.52 first gear, and maybe a 3.36 rear (2.52 x 3.36 = 8.47). What you will be doing is similar to starting off in gear one and a half in the Corvette( not quite like starting in 2nd , but close. The Corvette 2nd gear was 1.91 ( 1.91 x 3.36 = 6.32).

   Now you couple not much gear multiplication and a smallish engine, and driving off idle may necessitate revving up the engine some to get rolling, unless you have really good low end torque off idle. A long duration cam, and a single plane intake add power at high rpm, and lose power and torque off idle. Thus the need for a short duration cam and dual plane intake.

Also, with lower compression you need to close your intake valve somewhat early to build low end torque, so the need to have a short duration cam, and maybe on tight lobe centers ( 108 to 110).

clanofwolves wrote: With a 2.23 first gear and 3.15 rear, you don't have much gear multiplication (2.23 x 3.15 = 7.02). Most standard 350 cu. inch Corvettes back in the late 60's-early 70's had a wide ratio trans with about a 2.52 first gear, and maybe a 3.36 rear (2.52 x 3.36 = 8.47). What you will be doing is similar to starting off in gear one and a half in the Corvette( not quite like starting in 2nd , but close. The Corvette 2nd gear was 1.91 ( 1.91 x 3.36 = 6.32).    Now you couple not much gear multiplication and a smallish engine, and driving off idle may necessitate revving up the engine some to get rolling, unless you have really good low end torque off idle. A long duration cam, and a single plane intake add power at high rpm, and lose power and torque off idle. Thus the need for a short duration cam and dual plane intake. Also, with lower compression you need to close your intake valve somewhat early to build low end torque, so the need to have a short duration cam, and maybe on tight lobe centers ( 108 to 110). Thanks for the background and lesson in ratio's, I get what your saying. Sounds like I need to find a way to change the ratio. Would a rear end change make a better difference? I guess the Dana 20 only had the 3.15 and 3.54; would finding a 3.54 make a marked difference or is the real issue the small bore/ long stroke engine? I'm on a very limited budget and I don't have many access points for parts beyond this site, eBay (I'm very wary) and local Craigslist posts; so I need to maximize my efforts with small monetary moves. Again, thanks so very much! Dave

If I was staying on a budget, I would keep the gearing and use a stock, or near stock cam. You should change the rear if you want to gain mid range and upper rpm power by changing cam, intake, etc., or find a wide ratio T10 with a 2.64 first gear, which AMC offered through early 68 model year.