With the 370 gears , the car weighs about 3650 , does the 1/4 in 12:41 @ 107mph and goes through the traps at close to 5700- 5800 RPM . The 455 is a mild build and I have been told that I really should not rev this combo up to 5800 often, and it would be best to keep it around 5500 rpm for the power curve and engine longevity. I want a better cruising RPM , so will I be better off all around on the street and track with a 340 - 350 ratio? I'm running 325 50 15 drag radials (28" tall) now , but can run a 29 x 15.5 too. I want to do a 500 mile tour next spring , so the 370's and TH400 would drive me nuts. Cheers !
Your numbers don't add up. You can figure out RPM with this formula: 336/tire height X rear gear X MPH = RPM (no converter slip) With your numbers 336/28 X 3.70 X 107 = 4751 RPM. With converter slip, you should be close to 5000 RPM. Are you sure your tachometer is accurate?. Are you using an aftermarket torque converter? At 60 MPH, you should be at about 2800-2900 RPM
Its an aftermarket converter , roughly 3000 stall but not sure. It came with a big pile of Buick parts that I ended up installing in my 66 Beaumont SD . As far as I know the sport comp tach is accurate. I 'm pulling the tach signal from the old crane fireball ignition and rev limiter box.
You may be driving through the converter at the top end of the track. Your RPM should not be that high at 107 MPH. Maybe all you need is an efficient converter.
The converter feels a little slippery when I nail it on the freeway. I have the Lunati H230-245 cam, probably better off with a tight converter?
You are better off with the RIGHT converter. With the right converter, you will think you are driving a different car. The torque converter is one of the most important parts of your combination. A good one, is one that is built for your combination, not an off the shelf converter. That does not come cheap. PM Jim Weise and tell him about every aspect of your combination. He will have a converter built for your car at a great price. You will pick up ET and MPH. The car will be fun to drive.
Thanks , I will keep that in mind . I was looking at the 2004r built by extreme automatics, but I might do fine fixing up the th400 I already have. The OD sure would be nice on the 500 mile cruise I want to do.
