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"the tuning bible"

Old 09-04-2009, 06:30 AM
  #106  
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The plug I am using is a O.S. P3 (turbo - ultra hot) And yes I have added 1 shim to the head (the one delivered with the engine).

But if you tell me it is normal I give it try to use instead of 1/4 throttle short full throttle impulses.
Do you think this improves the behavior?

And I will set up the LSN like this:
The idle is for 15 to 20sec in "higher" idle before it falls down to the lower idle after a high speed ride.
This is the way you set up your idle?

Thanks in advance - come back to you when I tested it.
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Old 09-04-2009, 08:36 AM
  #107  
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Originally Posted by racer_hh View Post
The plug I am using is a O.S. P3 (turbo - ultra hot) And yes I have added 1 shim to the head (the one delivered with the engine).

But if you tell me it is normal I give it try to use instead of 1/4 throttle short full throttle impulses.
Do you think this improves the behavior?

And I will set up the LSN like this:
The idle is for 15 to 20sec in "higher" idle before it falls down to the lower idle after a high speed ride.
This is the way you set up your idle?

Thanks in advance - come back to you when I tested it.
The plug is perfect.
How much nitro do you use? If it is 25% you should remove the extra shim and retune (you'll have to set the hsn a little richer). The removed shim will set the timing correct (not ignite too late), and your engine will become easier to tune.

The 15 - 20 sec. depends on the fuel level in the tank. If you checked it with 3/4 full tank (and when the engine was race-warm), it should be perfect.

Back to M7H: He is the champ

Cheers
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Old 09-04-2009, 02:24 PM
  #108  
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But as racer stated he's using an ultra hot plug, I'm leaning to the idea that the plug actually is to hot....
But maybe he already needs this plug to compensate for a worn engine....
It's always difficult to judge over an internet forum...
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Old 09-05-2009, 11:57 AM
  #109  
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You are right it is difficult over the internet forum, not seen the engine and with a lot of ???.
But the engine is not worn. The P3 ultra hot is the standard plug for an OS V-SPEC engine. I have seen that a lot of other OS V-Spec engines have this behavior. But when you race faster the engine is mostly hot and you bump not into my issues.

And as you said it is normal - if I am using 1/4 throttle.
I will try next weekend to lean the LSN a bit as described above and to come in with short blip full throttle so that the engine is not loading up (At the moment I am on a business trip.)

Thanks a lot for you help - and even though it is difficult you have tried it and that's great.

I will post my feedback

racer_hh
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Old 09-06-2009, 11:57 PM
  #110  
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When it comes to load up at low RPM range, I've some knowledge from my plane engines.

Plane engines often come with a simple muffler. These mufflers can made too much backpressure, and make the engines run too rich in the low and mid range. A solution to that is a tuned pipe which have less backpressure, and therefore makes the engines runs perfect (and of course a big power improvement).

If nothing else helps, you could try another pipe.

As M7H suggested try to set the LSN as lean as possible (just before it goes ding-ding-ding) and see what happens.

An engine should not load up.
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Old 09-07-2009, 01:33 AM
  #111  
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In theory, before I put my car on the track, on the starter box, I lean the bottom (LSN) of my engines to the point they start "bogging" and then 1 step back. The top (HSN) needs to sound just a bit rich, but on the track it will be perfect. Ofcourse you first have to maybe run the car for 3 minutes or so, to get it to fully operating temperatures, but then this setting gives very good bottom response and power....
If you use your gas throttle as an on/off switch, the bottom (LSN) should be set a bit richer, but if you have a smooth throttle finger, this setting gives better engine response...
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Old 09-07-2009, 05:38 AM
  #112  
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Originally Posted by M7H View Post
In theory, before I put my car on the track, on the starter box, I lean the bottom (LSN) of my engines to the point they start "bogging" and then 1 step back. The top (HSN) needs to sound just a bit rich, but on the track it will be perfect.
Hi, may I know this method for all type engine? I am running STS cheapo engine

Another question is, may I know if we run LSN on lean side and HSN a little rich side, can cause damage engine ? Thanks.
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Old 09-07-2009, 01:08 PM
  #113  
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If you look at the carb in a schematic way, the HSN actually is the "main valve" of the engine. so the HSN also infects the bottom of the engine.
A Lean bottom with a rich top end, is more save then the other way around, unless you lean the top end again, but probably the engine will start bogging then....
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Old 09-09-2009, 04:49 AM
  #114  
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Originally Posted by M7H View Post
If you look at the carb in a schematic way, the HSN actually is the "main valve" of the engine. so the HSN also infects the bottom of the engine.
A Lean bottom with a rich top end, is more save then the other way around, unless you lean the top end again, but probably the engine will start bogging then....
Thanks. By the way, may I know "In theory, before I put my car on the track, on the starter box, I lean the bottom (LSN) of my engines to the point they start "bogging" and then 1 step back. The top (HSN) needs to sound just a bit rich, but on the track it will be perfect." will work on all type of engine? Thanks again.
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Old 09-09-2009, 08:30 AM
  #115  
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Originally Posted by tkhoo View Post
will work on all type of engine? Thanks again.
In my experience, yes.
But always be sure the engine is warmed up completely, including the chassis of the car.....
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Old 09-12-2009, 03:31 PM
  #116  
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my engine stumbles when i fully engage the throttle from idle what could this be high end rich or low end rich or lean?
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Old 09-12-2009, 04:10 PM
  #117  
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Originally Posted by forrestboy View Post
my engine stumbles when i fully engage the throttle from idle what could this be high end rich or low end rich or lean?
Sounds like your LSN is to rich.
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Old 09-18-2009, 12:00 AM
  #118  
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Originally Posted by forrestboy View Post
my engine stumbles when i fully engage the throttle from idle what could this be high end rich or low end rich or lean?
Let the engine warm up, then rev the engine up a couple of times to clean out any excess fuel in the crankcase. Put the car up on pit wall (if you're at the track) or on a car stand, then pinch the fuel line. If the engine stalls in less than 6 seconds the low-speed needle is too lean. If it takes longer than 8 seconds, it's too rich. If the mixture is too rich, you may also experience a considerable increase in engine rpm (hence the reason for getting the wheels off the ground), which tells you that the idle speed is too high. So, if the engine runs on for a long time after pinching the fuel line, lean the low-speed needle and reduce the idle speed. You want the engine to run 7-8 seconds after pinching the fuel line, and without a major change in engine idlle speed. It will rev up some, but not a lot, if the low-speed needle and the idle speed are set correctly.
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Old 09-20-2009, 04:08 PM
  #119  
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hi i have a ofna force .26 2 needle carb and i have a problem with it stalling from idle when i hit the gas it blows a lot of smoke and then dies and is the needle opposite the slide the low speed or mid range theres no needle on the slide itself so please help
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Old 09-20-2009, 05:04 PM
  #120  
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Be sure the engine is up to running temperature, then pinch the fuel line and count how many seconds it takes for the engine to stall, and also note how much the engine RPM increases. If it takes longer than 8 seconds to stall, and the rpm increases dramatically, then the low-speed mixture is too rich, and the idle speed is too high. If it takes too long to stall, gradually lean the low-speed mixture and adjust the idle speed as needed to maintain a reasonable idle speed. The clutch should not engage or even drag at idle speed. The idea is to have the engine stall in 6 to 8 seconds after pinching the fuel line.

If the engine dies faster than 6 seconds, the low-speed needle it too lean. Richen the mixture a little at a time (1 hour to 1/8 turns max) and recheck. You may need to adjust the idle speed upward a little to compensate for the richer fuel mixture.
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