|
#1
|
||||
|
||||
Gear and Converter Gee-Whiz
I've been running my '67 Belvedere at the local 1/8th mile strip, have made some changes this year that haven't made much difference but that some of you might be interested in knowing about if your project's anything similar to mine.
I used to run a 360 in this car, weight was 3500lbs on a local scale. 10" TCI streetfighter converter, 3.91 gears, car has power steering and I use a floor mounted shifter. Weight went to 3680lbs when I installed a 440. Best run with the 360 was 8.80, MPH 77. I shifted the 360 at 6000rpm; when I started in with the 440 it was at 5100rpm. The 440's a 1973 from a Winnebago, I installed ported 906 heads and a Comp Xtreme energy cam with .488/4.91 lift. Can't find out the original compression ratio, doesn't seem to have any problem running on 91 octane that we have at the local pumps. Total advance is 37deg. Slicks are 26" tall, 8.5" wide. TTI 1 7/8" headers. 850 TQ, electric fuel pump at the back. There's lots of area for improvement, I run with my tool bag, the spare and the original jack in the trunk, got a few other things rolling around on the back seat floor. All that matters is consistency with safety (have a driveshaft loop), so ultimately I just make changes to see what happens. I'll bring up RPM's at the line for better reaction times, otherwise leave off idle. I started off last year with the original cam in the motor, shifting the 440 at 5100rpm, times started off at 9.1 sec. When I installed the Comp cam, I raised the shift points to 5500rpm/5000rpm and went 8.9's. This year, I started off shifting at 5100rpm, car ran steady at 9.1's. Small tuning changes to the carb, into 8.90. One day at the track my shift light wound up at 5700rpm, car ran 8.70, then an 8.65 in a final (broke out). After that race, I installed a set of 3.23's (both gear sets with Sure-Grip) and that way only had to use second gear since it's only 1/8th mile. Plus, it's easier driving back and forth to the track. Ran 8.78's with that setup, shifting at 5700rpm, but did notice I could not start burnouts in second gear any longer. The converter would load up to 3k behind the 360, to nearly 3500rpm behind the 440 when using 3.91's behind each. I've read that with the torque of a 440 the gears don't matter so much, looks like that's true in my case. I don't have a line loc installed, I sure need one, though. MPH with each gear set came out to 77/78mph. At the end of June, I replaced the TCI streetfighter with a Dynamic Converter 9.5" version. During this process I found that my transmission mount was cracked and got a NAPA replacement which turned out to be 3/4" taller than the original. Looks like my old one was compressed (or something like that) and that's probably why I had to shim the axle mounts in order to get 5deg angle on the pinion (Superstock springs). I've got a poly mount that I need to install, then re-check the pinion angle. First time out, ran 8.77 shifting at 5500rpm. Shifting at 5100rpm this past week, it ran 8.79. I'm not sure what shifting at 5700rpm will do, but even if it drops another couple of hundredths, it isn't that big a difference over the TCI converter for that purpose. I gave the specs of my car with 3.91's when I ordered the Dynamic, so obviously the 3.23's aren't really a prime match...the TCI's an off-the-shelf one size fits all kind of thing, though. 60' times went from 1.95 to 1.91 bests with the Dynamic, so it's obviously helping the launch. For the 330' times, that was cut down by .01 and they wound up pretty close at the finish. The reason for making this change, however, was to get less slip on the road. I can definitely feel a stronger pull on the street, and on a hill nearby where I can hold a certain point on the pedal and watch the RPM's stay the same as the MPH rises, that rise is quicker with the Dynamic. It does what it's supposed to for all that, and if I were to pick out which of these to buy I'd spend the 100 dollar difference for the Dynamic. I've had the TCI for a long time, cost then was well below today's $500 price tag. Next up, I'm putting together a set of 4.30 gears. They're obviously not needed for what I'm doing, but I've been wondering what they'll be like to drive and race. I think I'm in for some traction problems. B-II |
#2
|
||||
|
||||
Great little tale. Keep it up.
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
A518 Torque Converter Lockup in 3rd Gear | 63Fury | Performance Talk | 3 | 09-06-2008 04:09 PM |
Calculate converter slippage and ideal gear ratio... | The Dartman | Performance Talk | 4 | 02-15-2008 11:42 AM |
stahl converter/gear ratio question | 73_RoadRunner | Performance Talk | 5 | 04-27-2005 10:34 AM |
gear and converter | fastback340 | Performance Talk | 6 | 10-20-2002 11:19 AM |
U.S Gear or Geniune Gear | machinehead | Ram Truck Chat | 4 | 03-18-2002 08:38 PM |