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Dialing in the LSN

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pnstalum

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Still trying to get my tune down. I am running a Dynomite Mach. 26 and cannot get a decent tune. I set the LSN & HSN back to factory refulgent and now I can't seem to get the truck running well. Right now it is idling okay, but when I accelerate it dies... almost immediately. Is this a LSN adjustment? I am assuming I need to lean out the LSN until I get a good launch, is that correct?

Thanks

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When it's idling, is it spitting a lot of raw fuel and oil?
If so, it needs to be leaned. If not, it needs to be richened.
What's the temp after it idles for several minutes? That's the sure way of telling if it's too lean or too rich.
DON'T make any adjustments till it's totally warmed up.
 
Yes... when it is idling it is spitting a lot of oil so I should start by leaning out the LSN. Can it be warmed up idling with some short revs or do I need to drive it and get it to full temp. Asking because right now it is not running good enough to drive for a long period of time... I think both the LSN and HSN are way to rich.

Thanks

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You drive it very slowly. That's actually better than letting it sit and idle. Short blips on the trigger from time to time to blow the snot out of the pipe.
Lean it a little more with each tank. When it starts to run a little better, pick up the speed a little. As it starts to get better, start leaning the HSN for faster runs.
 
Thanks for the guidance... Hope to do some tuning tonight, will report back on progress. I am comfortable wrenching, but still learning the art of tuning.

What are your thoughts on the Mach .26 as an engine... Seems to be in good shape.

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So i spent some time tuning tonight and things are getting a little better.

One question i have is when does the HSN take over. Is the low speed only for idle and initial throttle? I seem to have it idling fine now, but it is still spitting fuel, is that due to the HSN being too rich amd will lessen as i get the HSN dialed in? I will continue to tune... Trying to get to about 250 oF

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The HSN does a couple things. It's intent is to allow you to adjust fuel flow from about 1/4 throttle to wide open throttle (WOT). However, adjustments on it have an affect of overal fuel delivery to your engine. If you screwed it all the way in, no fuel would get to your engine, so any LSN adjustments would be pointless.

Most guys start by getting the HSN adjusted so it will run WOT pretty cleanly. This tells you that the overall fuel flow is in the ballpark. Then you adjust the LSN so it will idle for about 5-10 seconds, then take off cleanly.

A little adjustment here/there will be necessary as you get better with tuning and with weather changes.

Here's a couple tuning guides that may help you:

http://home.comcast.net/~98gmarquee/pics/misc/ParisRacingEngineTuningTechTips.pdf
http://www.rchobbies.org/cars_eng-tuning.htm

The mach engines aren't bad for what they are. Decent RPM's, ok fuel economy, hold a tune usually, decent power. They don't have a real long life though. At least not the 5 or 6 I've been involved with. 5-6 gallons and the compression drops greatly and flameouts ensue. But they do take to a repinch pretty well.
 
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The light bulb finally went off :D ... a great explanation and the pdf you attached provides good info! knowing the relationship between the HSN and LSN will help a lot. I am good tinkering mechanically, now I want to really become good a tuning.

As far as the Mach goes... it seems to be running well right now, but I bought this used and have no idea how many gallons have been through it yet. I've put a about 2/3rds of a gallon through so far. What is the best way to tell when an engine is on its way out? Flameouts, hard to start, doesn't hold a tune, all of the above? Would it make sence to rebuild this engine when needed or should I buy new when the time comes. Don't race... mostly bash around the yard & parks.
 

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