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2.3L Stroker Dyno Results and Power Discussion


revolve40

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7 hours ago, wagoner said:

Well, 0.045 would make it 1.15mm. That is excessive and will cause a stumble. Either way aim for 0.03/0.75mm. 

Yeah WOT mixtures in the 12’s sounds good ?

 

Not if you are running an MSD ignition. They recommend at least .050 in. for lower compression motors.

Chris B.

'73 ex-Malaga

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22 minutes ago, Chris_B said:

14.7 is way too lean for WOT operation, and good luck maintaining 14.7 AFR under any driving conditions. Ideal for higher RPM operations at WOT (say, >5K RPMs) is 12.5.

 

Agreed.  I was just using that as a landmark directionally.  Going 11 => 12.5 will cause the charge to burn faster, ergo less advance.

74 2002tii (Sputter) - Not entirely stock - Over 18K miles since full restoration in 2014

15 BMW X5 diesel (the bombed out roads of Houston finally won)

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Lot's of experimentation today.

 

Settled with 38mm chokes, 165 mains, and 200 airs. WOT AFR's are greatly improved (~12.5:1) and I can definitely tell it's wanting to climb above 6k vs. running out of steam as before. I did develop a pretty gnarly lean hole when getting on the throttle, though.

 

I might try F2 tubes (based on the below chart and 2300cc/4 = 575) and/or a "000" spill valve.  I may end up having to go back to the 36 chokes if I can't overcome the stumble.

 

Might even try 170 mains to get cruise AFRs into the low/mid 13's vs. high 13's low 14s where they are now.

 

Cylinder capacity (cc) Suggested emulsion tube
250 – 325 F11
275 – 400 F15
350 – 475 F9, F16
450 – 575 F2

 

Still not where I want it, but I think I'm making progress - once I've attempted to fix the lean spot, I'll get it back on the dyno to see if I'm actually improving anything. So many moving parts, but as a millennial, I'm happy to be learning how these carbs work.

Edited by revolve40
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Just now, Chris_B said:

Presumably this didn't happen until you changed your chokes and main jets...? Have you considered your pump jet setup?

 

Yeah - definitely the larger chokes have caused it.

 

My thought is to use closed spill valves before upping the pump jet size, but I’m just throwing ideas at the wall to see why sticks. It’s amazing how much you can spend on tuning these suckers.

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Is the lean hole on part throttle acceleration or WOT (or both)? I am running the closed drain valves and I did not notice much of a difference after installation. But, I haven't tried different pump jet sizes because my lean hole is not huge. I can feel it at medium throttle acceleration, and see it an my AFM at even light throttle acceleration.

Chris B.

'73 ex-Malaga

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Interesting on the spill valve not making much difference - thanks for sharing.

 

It really is very noticeable when stabbing the throttle for WOT (seemingly anywhere in the power band), and even part throttle acceleration. If I roll into it, it’s still lean, but can get through it and it’ll settle in to 12-13 AFR. I'm still thinking (hoping) it's the e tube. Everything I've read says to use an F2 for this engine. 

Edited by revolve40
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I realize that changing all of these things at once is like shooting myself in the foot, but I think I've settled on this timing curve. The only variable will be my all-in number, which I'll confirm on my next trip to the dyno.

 

IMG_5722.thumb.jpg.c5b4fe5d7fec9e8002f4da11be37f9a3.jpg

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Well, I couldn't help myself and swapped the 36 chokes back in tonight and rejetted with 155 mains and 190 airs. It runs like a bat out of hell and I can stomp on it just about anywhere in the range. The AFRs are dead on, with my transition leaning to 14:1 before richening back up. Still going to swap for the "no-hole" spill jet to see if I can make the transition damn near perfect. 

 

I know I can get the 38s to work, but going to drive it like this while I acquire various bits and pieces. The good news is I can swap chokes and rejet in under an hour now!

 

 

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3 minutes ago, revolve40 said:

Well, I couldn't help myself and swapped the 36 chokes back in tonight and rejetted with 155 mains and 190 airs. It runs like a bat out of hell and I can stomp on it just about anywhere in the range. The AFRs are dead on, with my transition leaning to 14:1 before richening back up. Still going to swap for the "no-hole" spill jet to see if I can make the transition damn near perfect. 

 

I know I can get the 38s to work, but going to drive it like this while I acquire various bits and pieces. The good news is I can swap chokes and rejet in under an hour now!

 

 

Nice work! I think the lingo around webers varies from hemisphere to hemisphere.

if your transition is a bit lean maybe look at your idle jet sizing - what are you running currently? 

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4 minutes ago, wagoner said:

Nice work! I think the lingo around webers varies from hemisphere to hemisphere.

if your transition is a bit lean maybe look at your idle jet sizing - what are you running currently? 

 

You're absolutely correct, I'm sill learning the lingo - I'm not referring to the off-idle progression/transition. I'm trying to describe throttle tip-in that occurs anywhere in the rpm band. My assumption that just a touch more fuel from the pump jet will help.

 

I'm running 65F9's now, so already pretty fat on the idle circuit.

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