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Old 05-22-2009, 09:24 PM   #1
abi
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Default help with OS Speed VZ-B V spec 2 tune.

Please help with tune, engine runs too cool even at lean stumble.

I can lean out the HSN until hesitation under load but still only 190deg F.

I use 25% nitro, factory head shims as supplied, and factory supplied plug, what do I need to do? Should I remove one of the shims to generate more heat?

Enging pulls hard and runs well but only 170 180 deg F when richened until lean hesitation is gone. Pipe is OS Speed 2060SC as recommended.

Help!
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Old 05-25-2009, 10:42 PM   #2
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Default Bump!

Bump, any advise on this one, why would this engine run so cool compared to my others?
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Old 05-27-2009, 10:40 AM   #3
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Default Final bump!

I'm thinking hotter plug or remove a head shim, what do you think?

Anything else I have missed?

Basicly it lean stumbles before going past about 190F. Richen it up on the HSN until lean stumble just disappears and the temp is 170F or so. Temp measurment technique/equipment is as I measure my other cars.

I have noticed the lean stumble is mainly at low RPM as I punch the throttle to wide open or near wide open, like nailing it out of a hairpin to power down the main straight. After the car stumbles through the mid/low range it picks up and goes quite good.

Could this be fixed by moving the 3rd needle or perhaps just fattening up the LSN so crankcase doesend dry up when throttle punched down low?
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Old 05-27-2009, 12:14 PM   #4
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it's better go to the off road section.
they will help you.
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Old 05-27-2009, 01:00 PM   #5
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Richen the low speed needle 1/4 turn and retest to see if the hesitation goes away. If you still have it, richen another 1/4 turn and retest. You will probably need to adjust the idle to keep the engine running after richening the low speed so much. It sounds like you have the low speed too lean and it's lean bogging under acceleration. Just keep richening the low speed needle until the hesitation goes away. Once it's set you can then adjust the high speed needle setting if it needs it for top speed.

DO NOT adjust the "3rd needle", that's the spray bar and affects the entire throttle range. You need to adjust both the spray bar and low speed needle at the same time when moving it and it only makes very fine adjustments to the engine's performance. It's set at the factory and almost never needs to be moved. Resetting it if it's been adjusted can be a pain if you don't have a great deal of experience tuning engines.

As for the temperature, tune the engine for best performance and then temp it for a reference number. I usually don't temp my engines and just tune for performance. So many factors can affect the temp of an engine while running. A well tuned engine will run at one temp in one set of weather conditions and another temp in different weather conditions.

Good luck!
Socko
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Old 05-28-2009, 01:04 AM   #6
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Thanks socko, will try this on the weekend, makes sense.

Thanks again.
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