Small carb. adjustments make a big difference

1969mach1351 · Nov 12, 2005

In the 1/4 mile with a dual plane manifold I was running a 13.08. I switched to a single plane and 1/2 inch spacer and ran a 13.2. Got a wideband and richened the secondaries by 4 sizes and ran a 12.89. I'm amazed at how 4 jet sizes makes three tenths difference and two MPH in the 1/4 mile.

ddonaca351 · Nov 13, 2005

LOL... yeah, and with traction (2.xx 60') you'd gain another 2-3 tenths.
Try a set of drag-radials or some gooood sticky street tires.

DD

thehueypilot · Nov 13, 2005

Wideband takes all the guess work out of air/fuel readings.......I wish I had bought my Innovate meter a lot sooner.

10secgoal · Nov 13, 2005

KEEP GOING UP !!!
Make sure the jets are equal from front to back. There should be about a 10 point spread or so from front to back. Widebands are great, but only tell you what the gases are showing. If you go to rich in the back, the meter could should a good AFR, but may be lean up front. Like if you have 75's up front and 90's out back.

iskwezm · Nov 13, 2005

thehueypilot said:
Wideband takes all the guess work out of air/fuel readings.......I wish I had bought my Innovate meter a lot sooner.

can you give a little more info on the LM-1,i have read a little about it,but what can/cant it do and would i really need it on a blown application

Thanks

thehueypilot · Nov 14, 2005

The meter is a wideband meter so you can set the idle A/F in real time. I use it for drag racing to record each run to evaluate the A/F vs. RPM. It will record up to approx 80 minutes so just before I stage, I hit the record button. The graph will show you your RPM's (shift points) and A/F for the entire run. I start out adjusting the front jets in the garage by reving the engine to about 3.5k to get the A/F reading for the front only. I want a reading of about 12:1 on the front only then adjust the back to be eight numbers greater. (Vac Sec Carb) The actual run will show your total A/F.(Front and Back combined) Check out there website: www.innovatemotorsports.com

10secgoal · Nov 14, 2005

Huey what happened ? I thought you went to a DP an loved it ? Go to the vac secondaries because of traction ?

thehueypilot · Nov 14, 2005

I switch carbs like I change underwear.....daily. (not really....the carb part) I had too many random bogs at launch with the DP with put me out of the race a couple of times (maybe due to change in temp?), but the Vac sec seems to be just right. My best run to date was with the 850 Vac Sec. I am building a 750 Vac Sec to experiment with as well to get the incoming air at it's highest velocity.

Edbert · Nov 14, 2005

Stupid question, not that that ever stopped me before, but how can it gauge A/F without a computer/EFI? Is there an O2 sensor and a metering block of some sort?

10secgoal · Nov 14, 2005

Nope, o2 sensor in the exhuast. Hooked up to a guage that gives you the reading. Unlike a o2 with a computer, you have to make the adjustments.

thehueypilot · Nov 14, 2005

Edbert said:
Stupid question, not that that ever stopped me before, but how can it gauge A/F without a computer/EFI? Is there an O2 sensor and a metering block of some sort?

It has it's own hand held computer with an LED readout with a cable that plugs into a standard Bosch oxygen sensor and a inductive clamp to read RPMs. It's info can be download into a PC to replay the run in real time and/or study the graphs.

10secgoal · Nov 14, 2005

thehueypilot said:
I switch carbs like I change underwear.....daily. (not really....the carb part) I had too many random bogs at launch with the DP with put me out of the race a couple of times (maybe due to change in temp?), but the Vac sec seems to be just right. My best run to date was with the 850 Vac Sec. I am building a 750 Vac Sec to experiment with as well to get the incoming air at it's highest velocity.

yeah, it's very hard to tune the pumpshot if you are having traction problems. Spinning causes a lighter load. So you don't notice that's it lean. The next time around, when it hooks better, you have a bigger load, then she goes lean. I had a helluva time. I'd finally get it to hook, then it would bog. Then I'd up the pump shot, and it'd spin because of more power. went round and round with the for about 3-4 months.

thehueypilot · Nov 14, 2005

I could not hit my dial in because of the random bog or the drastic outside temp. It keeps changing from mid 70's during time trails to mid 50's during eliminations. I hope to have the traction problem solved this Sunday with 3.55 gears.

iskwezm · Nov 14, 2005

thehueypilot said:
The meter is a wideband meter so you can set the idle A/F in real time. I use it for drag racing to record each run to evaluate the A/F vs. RPM. It will record up to approx 80 minutes so just before I stage, I hit the record button. The graph will show you your RPM's (shift points) and A/F for the entire run. I start out adjusting the front jets in the garage by reving the engine to about 3.5k to get the A/F reading for the front only. I want a reading of about 12:1 on the front only then adjust the back to be eight numbers greater. (Vac Sec Carb) The actual run will show your total A/F.(Front and Back combined) Check out there website: www.innovatemotorsports.com

SOLD,thats what the g/f's getting me for Christmas

Edbert · Nov 15, 2005

iskwezm said:
SOLD,thats what the g/f's getting me for Christmas

Does she know that yet or do you just show her your receipts and say thank you? It works the latter way at my house.

LOL.

Small carb. adjustments make a big difference

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