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Discussion Starter #1 (Edited)
This past weekend I raced the NMCA True Street class at Summit Motorsports Park in Norwalk Ohio. Had a blast but am wondering if I may have a fuel or carb issue. I made some jet and timing changes and the car didnt really react at all.

1st run on Friday

Jets 73-83
32 deg timing
20 psi tire

1.61 60'
4.63 330'
7.18 1/8
95.82 mph
9.42 1000'
11.32 1/4
118.27 mph




2nd run on Friday

Jetted up primary to 75
Everything else the same

1.59 60'
4.61 330'
7.16 1/8
95.90 mph
9.40 1000'
11.31 1/4
116.46 mph

/\ Car seemed to hook better, but gained mph at the 1/8 and lost 2 mph at finish???



3rd run on Friday

Jetted up secondary to 85
Lowered tire pressure to 18 psi
Everything else same

1.59 60'
4.62 330'
7.18 1/8
95.65 mph
9.42 1000'
11.33 1/4
117.36 mph

/\ Car slowed down .02 through run but gained almost 1 mph at finish line???


1st run on Saturday

Jets 75-85
36 deg timing
18 psi tire

1.60 60'
4.63 330'
7.18 1/8
96.04 mph
9.41 1000'
11.31 1/4
118.42 mph

Before my 2nd and final test pass on Saturday, I jetted the secondary up to 87 just to see what would happen to the mph. I was expecting it to fall off a bit because I really cant see this motor needing that much and the DA was around 2500. I figured I would do it as a test since I had the chance.

Guess what? I guess due to the fact that it was so crowded and they were behind schedule with all the other events going on they canceled our 2nd time trial run and we had to report to the drivers meeting, so I was stuck with the 87 jets, and no time to change them. Then to the 30 mile cruise, and then to the staging lanes, and 3 back to back runs down the track. The only thing you can do is raise or lower your tire pressure. Not allowed to add fuel, not allowed to open your hood or trunk.



The 3 passes below all have the same setup:

75-87
36 deg timing
18 psi tire

1.59 60'
4.62 330'
7.18 1/8
95.54 mph
9.42 1000'
11.33 1/4
117.86 mph


1.61 60'
4.65 330'
7.20 1/8
95.87 mph
9.43 1000'
11.33 1/4
117.80 mph


1.62 60'
4.70 330'
7.27 1/8
95.46 mph
9.51 1000'
11.41 1/4
118.33 mph

/\ 60' fell off a bit so it must have spun which
caused the final mph to go up but why did I lose mph at the 1/8th???


The car is consistent, more so when I dont change anything at all. But isnt it odd how consistent it remained even with the the jetting changes? Or am I wrong in expecting to see more differences run to run after changes are made? I'm just wondering if maybe its right at the edge of not getting enough fuel or a carb issue.

I have a Holley Blue with -8 running from it to the engine. I did check the fuel pressure during a full throttle pass earlier in the year and it never dropped below 6psi.
 

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Discussion Starter #3
You ever log the weather? What fuel, comp, timing, .....
I didnt log the weather for each run but I know the DA was roughly 2200-2500 during both days.

Fuel - 93 pump gas
Comp - 10.25
Timing - 32 deg locked and then 36 for the last 4 passes
 
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