Quote:
Originally Posted by casrak7
We have a mustang weighing 3120 at the starting line. 355 chevy. 12.4-1 compression. 263/267@.050, .710/.660 on 106 in at 102 ic. Strip dominator. 1050 quickfuel 4150 carb. Th350 trans w coan brake. Large heads....ported dart iron about 232ccs.
Flow good air, but we know they're very large on this combination. We know the cam is small, but this was a "use what we had" deal. Converter is flashing about 5800, and the fallback rpm is about 6500. After reviewing the gopro footage. It is very obvious that the fall back rpm needs to be closer to 7000, as the shift recovery on the 2-3 change is lacking. The car could use the extra starting line rpm as well. Currently the car runs 10.45@129.89. Runs 6.69@103.8 in the 1/8. 60 foots only 1.45 most times. I believed we've tuned most of the power out of this, but it was suggested that we try even more timing. Right now, best times and mph have been found with 40 degrees. But a very knowledgeable and fast friend has told me that he's found certain small chevy engines that performed the best with a much as 46 degrees, and that we should continue experimenting with it. Converter will get sent out to be loosened up over the winter another 500 rpm. Currently crossing at 8000 or so with a 4.88 and 28x10.5x15 stiff wall tires. Any ideas would be greatly appreciated.
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Good morning to all,
Just off the top of my head, try changing the First and Second gear ratio's to somewhere in this area - 1st gear 2.70 range and 2nd gear 1.70 range.
You should dyno the engine and run your timing changes there, fuel used will have a bearing on your timing as well, coolant temps too. Try to bring and run as much of your combination on the dyno that you run in the car.
You'll need to see where the power is and where it falls off. One day dyno testing will probably give you more positive information then a season's worth of racing.
P.S. with the additional power you should find , you might have to go to a 30" tall rear tire.
Best of luck on your endeavors.
Respectfully,
Henry Kunz 1534 H/SA.