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 Is this normal 
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Joined: Wed Feb 20, 2013 11:38 pm
Posts: 403
Questions on the log attached.
!. Does it look like I have to much squirter on the launch?

2. How can the AFR be so spikey when the throttle is at WOT for almost the entire run?

3. My cruise back to the trailer has readings so lean I would think it would be popping. Are your cruise numbers this lean.

4. Shouldn't lamda numbers be around 8 on a run?

This is a 427 BBC, gas burning 1050
IJ 037
IAB 066
MAB .023
MJ 98
TSJ 058
Squirter 038 with yellow cams
Timing at 37
plugs NGK 9

Attachment:
9-13-14 e1 final.rpk [336.49 KiB]
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Wed Sep 17, 2014 8:30 pm
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Joined: Thu Mar 28, 2013 6:09 am
Posts: 726
98 jet?? Only had a 94 jet in my 540...


Wed Sep 17, 2014 8:40 pm
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Joined: Wed Feb 20, 2013 11:38 pm
Posts: 403
I started with 92's but the O2 screamed lean so I went up and up and up. I haven't ever shut the engine down at the end of a run and read a plug. I haven't ever run a test and tune day to determine what jet makes the most power. I've run almost all index races that last couple years with restrictor plates. The o2 always reads lean, but the engine never pops and I don't see any pepper or aluminum on the plugs. I've put new sensors in and they read the same. Larger jets move the graph a little, but not much.


Wed Sep 17, 2014 10:23 pm
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Joined: Fri Feb 08, 2013 5:50 pm
Posts: 2302
98's are way rich for a non oxygenated fuel in a 1050, and 9's too cold for a NA engine. Idle and cruis AFR are not important on an engine with open exhaust, you get too much dilution from reversion of atmosphere at the end of the collector. And don't jet to AFR, jet to time slips/MPH.


Thu Sep 18, 2014 10:42 am
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Joined: Wed Feb 20, 2013 11:38 pm
Posts: 403
jmarkaudio wrote:
98's are way rich for a non oxygenated fuel in a 1050, and 9's too cold for a NA engine. Idle and cruis AFR are not important on an engine with open exhaust, you get too much dilution from reversion of atmosphere at the end of the collector. And don't jet to AFR, jet to time slips/MPH.

When I first used this carb I had 92's and 7's. The AFR average during the run was 14.53:1, which scared me a little so I tried to fatten it. I'll do a test session and jet for mph like I know I should. What plug would you suggest?


Thu Sep 18, 2014 11:14 am
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Joined: Fri Feb 08, 2013 5:50 pm
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I use 7's up to 14.5 to 1, you just need to be conservative with timing and run the engine cooler until you get a read on the plugs over 14 to 1. Anything over that run 8's.


Thu Sep 18, 2014 8:15 pm
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