Carb tweak
Carb tweak Ok guys need a little help. Mods in sig. I have a quick fuel slayer 750 vacumm secondary. 70 main jets, 82 secondary, 6.5 power valve. My afr at idle is around 14.1. Then while light accelerating from 1500-2500rpm it's rich at 10.9. Then when cruising around 2300 rpm I have it running 14.5 afr. When I kick it it goes a little lean at 15.0, need to play with the pump cam some and the secondary opening rate. WOT is around 12.9. I'm mainly wanting to fix the light acceleration rich problem any idears? Thanks
Folks may not agree but with my 750 slayer I solved all it's pig rich under load issues simply by removing the power valve and installing a block off plug.
It's a $5 part worst case scenario you try it and it tells you your problem is powervalve related or not. If you block the PV and the overly rich condition goes away then you know you need to either go to a delayed power valve or start cutting back on the PV enrichment jet size
It's a $5 part worst case scenario you try it and it tells you your problem is powervalve related or not. If you block the PV and the overly rich condition goes away then you know you need to either go to a delayed power valve or start cutting back on the PV enrichment jet size
post up if you figure it out. my QF 850 does the same exact thing. 80/92 jets with stock power valve. idles 13.0ish and goes pig rich at 5%ish throttle. the same 10.9 crap..once the converter locks at 50mph it cruises right around 14.5. i may give QF a call and see what they say.
Chances are it's not your power valve unless it is coming on way too early.
I assume you checked the float levels and fuel pressure. also all the gaskets good, power valve torqued down nice and tight. Check all the air bleeds for obstruction (blow compressed air through them or chase them out with a piece of wire).
If all good find your idle feed restrictors and make them smaller. IFR are like main jets for the cruise circuits. Look at post #18 in this thread
https://ls1tech.com/forums/carburete...ce-needed.html
I assume you checked the float levels and fuel pressure. also all the gaskets good, power valve torqued down nice and tight. Check all the air bleeds for obstruction (blow compressed air through them or chase them out with a piece of wire).
If all good find your idle feed restrictors and make them smaller. IFR are like main jets for the cruise circuits. Look at post #18 in this thread
https://ls1tech.com/forums/carburete...ce-needed.html
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here is a question. if it cruises at 14.5 with the converter locked at 70mph, wouldnt changing the IFR lean out that higher rpm AFR too? or am i thinking about it wrong. what the OP and i are experiencing is 10.9 AFR at extremely light throttle (cruising around a neighborhood or slow traffic) then it leans up to the desired AFR at cruising speed.
from what i've read on the interwebz... If it goes rich to lean then you need to put in a bigger IAB to delay the circuit flow.
everything on the internet is correct....bonjor
sorry i'm still trying to wrap my mind around everything. is the above statement true? i know the tech at QF told me to reduce the IFR size, but i'm reading conflicting information on the web.
from what i've read on the interwebz... If it goes rich to lean then you need to put in a bigger IAB to delay the circuit flow.
everything on the internet is correct....bonjor
sorry i'm still trying to wrap my mind around everything. is the above statement true? i know the tech at QF told me to reduce the IFR size, but i'm reading conflicting information on the web.
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Verdad Gallardo I'd like to hear more as we'll. I'm satisfied with the way it runs except for the light acceleration (city driving) which is about 70% of the driving it does haha so it's killing mileage
Found this I'm having a similar condition that is listed under enhanced tuning. May give this a try. http://www.innovatemotorsports.com/r...FI_mileage.php
Found this I'm having a similar condition that is listed under enhanced tuning. May give this a try. http://www.innovatemotorsports.com/r...FI_mileage.php
". The IFR is the gatekeeper of fuel for the idle/cruise circuit. Experienced tuners decrease IFR size when they need to reduce idle/cruise below 1/2-3/4 turn from fully closed in order to get 14:1 air/fuel ratios at those speeds. The IFR is flooding the idle circuit with fuel and causing the idle and cruise to saturate. Alternatively, tuners can increase IFR size if the engine is starving for idle/cruise fuel (beyond 2.5 turns out from fully closed/seated idle/cruise screws to keep the engine running). "
Last edited by TXsilverado; Apr 30, 2014 at 06:48 PM.
When I put the wire in the low speed fuel passage, I had to bring my idle mix out allot. But trying to cruise 5th gear at 30 will go retarded lean, so not sure where I'll deal with that.