Hey all, this post maybe should be how not to tune a car. This spring, Blair was nice enough to send me a custom 1100 cfm carb to test (vs my basic 850 dbl pumper) to see if it would get me closer to my 10.50 target ET. This test was at BIR on a very hot 4th of July. It was so hot they actually shut down racing for the first time ever due to hot track temps. They put water on it to cool it and later in the day got it dry and resumed racing. Due to the heat, Blair suggested I dial in a little more timing. Previous runs had my trap speeds from 122-123mph. With the 1100cfm and more timing I was now running 124-125mph trap speeds. Unfortunately my 60ft times were now in the low 1.50s instead of the 1.45-1.47 I had been running. I chalked it up to the extreme heat at the time. I made 10 passes with the 1100 carb. during those passes I tried both jetting and suspension changes to try and improve my times, but they made no difference. I wanted to verify if it was the carb or the timing that improved my trap speed so after the 10 passes with the 1100, without making any other changes, I put my old 850 on and the car ran the exact same times and trap speeds as it had with the 1100 carb. Based on that I decided to send the carb back to Blair and have since been focused on slowing the car to run the 11.0 index. I even have run a 780 vacuum secondary carb. With the secondary's locked out the car runs 11.60's on 2 barrels. I drilled some holes in my vacuum diaphragm rod and can control how far the secondary's open by moving a hair pin to higher or lower holes. This seemed to work pretty well, although this winter I think I may install a changeable restrictor plate setup to control my ET's. I like the thought of that better as the carb will be wide open and running fully on the mains and not stuck running off the transition circuits on the rear 2 barrels. Then I can just run my 850 dbl pumper again and change restrictor plates as needed to dial the car in. One thing for sure is the motor likes more timing than we initially thought. Blair had us run 32 degrees (locked out dist) for my dyno test at Jay's where the motor made 600hp. I think with the switch from the Harland Sharp rockers to the T&D's and running more timing the motor may be making more power as I am now consistently running trap speeds of 125-127mph. My new problem now is, even with new slicks, I cannot get my 60ft times back under 1.50. Sorry for the long rambling post. I love my BP motor. It is running stronger all the time. Jim
