Lean after few seconds - Ford Mustang Forums : Corral.net Mustang Forum
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post #1 of 10 Old 04-07-2019, 11:25 PM Thread Starter
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Lean after few seconds

I'm having an awful time with a lean issue, I'll try to add all the things I've done cause I need serious help! Setup is 347 with turbonetics 67 mm turbo, blow through carb, boost ref reg, boost reference msd, makes 12 psi, a1000 pump, all an lines w/return, timing is 28 deg total, plug gap is .022, I'm sure it's not all listed but feel free to ask.
So, I can take the car out and drive it and it's decent, was in the middle of tuning. Wideband is 12.5 at cruise and 13.3 under boost, it was hitting good 2-3 gears. Came back and made jet change, that's how I made the 13.3. Then I went down and now I mat it and it holds 13.3 for about 2-3 seconds and then it spikes the wideband and lean pops. Since this I added the a1000 pump, it's making fuel psi so I'm now stuck, I don't even know where to go from here...


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post #2 of 10 Old 04-07-2019, 11:28 PM Thread Starter
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Fuel psi is 4lbs at idle, boost reg is 1:1. Timing box box pulls 2 deg per pound of boost...


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post #3 of 10 Old 04-08-2019, 06:58 AM
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You are going to melt that motor down if you keep going into boost.
Your fuel pressure should be rising 1psi per lb of boost.
Your a/f is way lean under boost. At 10psi I would shoot for low 11s a/f.
You're also not running enough timing. You are going to damage the exhaust valves pulling 2 degrees at 10psi boost.
You have to figure out why you came low fuel pressure.
I wouldn't get into boost till you figure it out.
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post #4 of 10 Old 04-08-2019, 07:05 AM Thread Starter
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Fuel psi is 1:1, it has around 15 ish psi under boost, and I have huge jets in carb 99 sec 84 pri. Is there a trick to fatten it up?

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post #5 of 10 Old 04-08-2019, 04:45 PM
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Is that carb setup for boost? THe float ports need attention or the boost pressure will prevent them from filling.
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post #6 of 10 Old 04-08-2019, 05:53 PM Thread Starter
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Well, carb was "converted" to blow thru, but it did come off a boosted sbc

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post #7 of 10 Old 04-08-2019, 05:58 PM Thread Starter
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What exactly are the float ports?

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post #8 of 10 Old 04-08-2019, 08:35 PM
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post #9 of 10 Old 04-10-2019, 07:00 AM
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Quote:
Originally Posted by dy85merc View Post
Well, carb was "converted" to blow thru, but it did come off a boosted sbc
Did the SBC melt his motor, then sold carb to you? I would never trust a used blow through carb without going through it yourself to make sure all the proper modifications have been done.

And I agree that total timing is too low, since you are pulling a good bit of timing out under boost as well.

93 Notch 347 twin 66s TH400...8.54 @ 162 Radials

91 Notch 410W Novi 2000 5 speed...10.99 @ 136
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post #10 of 10 Old 04-10-2019, 09:49 AM
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You might have pressure before the carb but maybe the fuel isn't getting into the bowls? Don't they make a higher flowing needle and seat?

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