justintimeracing
Registered: 12/19/11
Posts: 7
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| | 02/09/12 at 12:48 AM | Reply with quote | #1 |
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| I switched from gas to methanol a year ago with this carb it had a real bad hesitation off the starting line. Patrick told me to change the idle bleeds from .070 to .055 and it helped some then he told me to drill the idle feed restrictor .006 bigger and that helped enough that I raced it most of the summer. l tried jetting the main jets up and down with no gain or loss of mph. Then one night at the track I plugged the front power valve and jetted it 160 in all 4 corners and it picked up et and mph. I started going down in jet size from there and ended up at 150 in all 4 to net the best mph. My question is now that I'm so far from the way it came that I'm not sure what's going on the plugs still look rich and it takes forever to warm up but it runs good down the track. Any help would be appreciated |
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PRO-SYSTEMS
Moderator
Registered: 12/16/11
Posts: 302
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| | 02/09/12 at 12:56 AM | Reply with quote | #2 |
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The hesitation on the whack is probably more squirter related than anything.
Or its too cold, get a thermostat in it (160 degree) to help it heat up faster.
If you are jetting down quite a ways from my baseline ..it typically means that your intake to exhaust flow percentages are less biased towards exhaust flow side (mufflers or restrictive headers..needs more exhaust lift or duration on camshaft). SO be aware that we can probably address the engine program in those areas and pick up some more power. Or it could just be a weak ignition...but thats doubtful.
Keep us posted.
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justintimeracing
Registered: 12/19/11
Posts: 7
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| | 02/09/12 at 01:10 AM | Reply with quote | #3 |
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| I warm it up to 160 before each pass but it takes a long time even with the electric water pump off. I run 3" pipe and borla xr1 mufflers I've never tried it with no mufflers the headers are 1 3/4" x 30 with a 3" collector. Your right about the flow the exh flows 65% of the int. Most good heads are in the 75% range from what I see advertised. What about the front power valve being plugged is that good or bad? |
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PRO-SYSTEMS
Moderator
Registered: 12/16/11
Posts: 302
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| | 02/10/12 at 03:06 AM | Reply with quote | #4 |
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The tip in signal would be increased if we got the percentages inline. But the PV plug is helping as it supplies more initial fuel out the booster quicker. Now that we know the reason (flow percetanges are off), we can go off the chart and just jet for best mph and race it.
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justintimeracing
Registered: 12/19/11
Posts: 7
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| | 02/10/12 at 09:49 AM | Reply with quote | #5 |
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| So I should put the power valve back in an then jet for mph or do I need to send the carb in to be recalibrated? |
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PRO-SYSTEMS
Moderator
Registered: 12/16/11
Posts: 302
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| | 02/10/12 at 09:56 AM | Reply with quote | #6 |
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Leave it plugged and square jetted and jet for best mph. You are just required to go away from the norm on the base calibration due to your flow percentages. Its still ok. I am as tight with your money as I am my own... don't spend any money with us on a recalibration. It sounds like you are very close now.
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justintimeracing
Registered: 12/19/11
Posts: 7
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