akirahz

I'm having a tuning dilemma here, after a few runs some times my car will just shut off at or around idle speed, i noticed the engine was very hot.. so i decided to quit running it for now till i can maybe figure it out.

Also some times when i run full throttle and get my speed quite high, the engine will just shut off.

I made a short video of me running my car around.

Maybe one of you can tell if my engine sounds like its running too lean or too rich on the high or low side? Im actually having trouble figuring out which needle is which.. well im pretty sure the HSN is the brass needle at the top.. but i cant quite figure out which one is the LSN. I've never messed with this type of carb before, only 3 needle rotary ones

here is a link to my carbs specificaitons which points out various needles but doesnt label them HSN/LSN.. infact it has 4 needles in all? I'm guessing either the Idle screw is the LSN or the spay bar is the lsn? i know the idle/air screw is for the carb gap and the big brass needle is the HSN. But cant figure out which one is the LSN for certain.

http://www.rbproducts.com/mainEn.php...0.12%20engines

Heres the video of my car running for a few minutes, it ran for a total of about 3-4 minutes before it shut off by itself.

+ YouTube Video

Thanks for any and all help

blis

It's always hard to tune a car off "circuit".. And tell us how the run in proces went!

To get a good handle on the tuning you need to warm it up under load on a circuit with long straights and corners to get a good idea how the low and high mixtures are set when the metals have warmed up.

If you are a newcomer.. http://www.beachmumsracing.org.au/fyi/santalovesnitro

Cheers..

h

PS: A performance engine wont sit idling happily forever, you need to give it a squirt every 5 seconds or so to clear the crank case. Also keep a close eye on your clutch, a sticky clutch will stall an engine... Couldnt quite tell if you cut out windows... oh there you go.. open the back window completely.

PMSorber

Dear Akirahz,

Let me give it a try. From the R&B website:

A = HSN
B = LSN
C = Stationary
D = counter LSN.

Set D alway's flush with the housing and dont touch it anymore, it shifts the LSN / HSN setting.

What I see in your video is that the engine seems to be running lean, normally we would like to see a gush of smoke every time you hit the throttle from low rpm. In general you could do the following:

Set the LSN fat (1 full turn out, stationary will go down and you will see a lot of smoke and poor torque at low rpm) and tune the engine first on HSN, after that tune the LSN and Stationary.

JJBinks

Make sure you are see smoke through first and second gear. The only time you shouldnt see smoke is for exampe on a back stretch while racing, you wont see smoke after being wide open and winding out for a second or two. other than that you should see smoke always. In this case the advice given above is pretty good. Richen it up a bit on the low and high.

Do you have a temp gun? if so what temps are you seeing? and if not Get one!!

RogerDaShrubber

iTrader: (6)

Looks a bit lean on the low end and high end to me, mid range seemed fine, nice fine film of smoke, cut a hole in the front window for ventilation and either take out the side windows (if racing and thats what your rules require)or the rear (if bashing).

As someone said before me, you need to see a thin but constant film of smoke out of the exhaust right through the rev range, does not have to be a lot, but it should be there. Also, hit it with a temp gun after a good 5 min run on a track, to see how hot it actually is.

akirahz

Ok thanks guys for the assessment and especially thank you for the needle identification for the carb.

The front window does have a large round hole in it, and there is a hole in the back of the car under the spoiler but its not that large. What would be the best tool to use to cut this plastic with? Just a box cutter or a power tool of some sort?

I had one guy tell me the LSN sounded like it was running rich because it sounds more like a gas engine at idle.. but you guys are telling me the lsn is too lean. More often then not i dont see much smoke at lower rpm so im guessing you guys are probably right and i'll richen the lsn up a bit and then test the hsn again and see if it needs a 1/8th turn or more to richen it up. I do not have a temp gun though so i can't check the engine temp.. what is a good gun to purchase does anyone have a recommendation ?

Again I appreciate all the input from you nitro guru's out there and will put this knowledge to use as soon as it stops raining

RogerDaShrubber

iTrader: (6)

Here is an ok walk through on how to tune an engine, http://www.youtube.com/watch?v=9M4j_-HGRlQ it is a reasonable guide on what to do and what not to do.

akirahz

AH! ive watched a ton of ali's videos, hes a real informative guy

I think i found out one of my main problems.. my glow plug went bad on me, at full throttle it was just shutting off, but today it wont start up at all and i hear no spark going on..

Little did i know it requires a rounder turbo style glow plug.. i was out and about near my local hobby shop so went in and looked around a bit.. I ended up wasting 8.99 at the hobby shop for a regular McCoy glow plug only to find it doesnt fit my cars engine.. sheesh im an uber noob.

I checkd the old glow plug and its barely glowing at all and it was quite wet as well with fuel. I guess i should of checked the old plug first before buying a new one but i was in the neighborhood of my shop at the time i thought of getting some new ones, guess its a good thing I decided to only buy 1 for a test haha

Geezatec

Igniter fully Charge?? Temp of engine in operating temp?? Condition of GP? Is it sooty with blk carbon?? Or is it wet with fuel, Or dry?? Try turning the HSN a 1/2 turn CCW. You a lttle more fuel to start, and retune, it'll probably You had it leaned out too much running it the day before. It's difficult to say , cuz, everybody will be different on barometric pressure. Try richen the HSN, then retune.

Recharge your igniter 8 to 10 hours.

akirahz

Pretty sure the igniter is fully charged, i dont know what the engine temp is i dont have a gauge yet. The GP is dry and not very sooty or anything, its pretty clean actually but it doesnt glow as bright as my new glow plug i tried, no where near as bright and they are both medium #5 plugs.. only one plug wont fit this engine is all.

I put my igniter on the charger for the night and will wake up early and give it a try again and see if i can get the engine started.. if not, ill prob run down too the hobby shop and pickup a turbo plug and see if that gets it running again.

The day before when i could start the engine, it would just die right away when i hit the throttle, it wouldn't hesitate, it would just cut out and die instantly. But now it doesn't even act like its sparking at all so im hoping the glowplug itself is the culprit for an easy fix.

Theres a distinct sound i can hear when i know the engine's glow plug is actually working, it just sounds different, but now when i try to start it, its like theres no glow plug in it at all, just bumping the fly wheel with no glow/spark at all yet the glow plug itself does give off a faint glow when i test it to the igniter, the meter on the igniter is also in the middle of the green area so i dont know for sure.

Geezatec

GP not sooty or dry, after trying to start. No fuel is being supplied. Turn HSN CCW to let fuel in. What's your airgap on your throttle opening?? Break your engine in GP should be sooty, With lots of exhaust smoke. Every day the car sits, weather changes, retune each day. When you're done you got it so lean, that it doesnt start. Half turn CCW is a good default at start up.

akirahz

Well i cant get the engine to run good at all now, i can get it started, but every time i give it the gas it flames out, no matter what tuning i do to it, and some times if i mess with the engine or tip it around during idle, itll rev high and erradically like it has a vaccume or air leak some where. I dont know if this engine was ever sealed or not but i dont have the tools to take it apart i dont think.. id have to buy some and not sure where i'd begin checking for leaks as theres about 5 or 6 places it can have air leaks i guess according to this nitro engine book i picked up. Seems like when i mess with the low needle carb slide boot it revs oddly..

Is it possible for the low end needle or slide boot to have an air leak there? I'll shoot a video of the problem tomarrow for more insight.. i dont want to give up just yet.

RogerDaShrubber

iTrader: (6)

When in doubt, reset the engine to factory default settings and start over, also check to see if you are getting pressure in the fuel tank, you might just need to change the fuel lines as you might not be getting enough pressure to push the fuel up into the carb.

Geezatec

Few more questions. What airgap you have on throttle? And How many turns on HSN to close?? You say you dont have a temp gauge. Use saliva on your finger, saliva will evaporate slowly, If it boils off you are running too high and too lean. Answer question first.

akirahz

How do i check pressure in the fuel tank?

I set the engine back to factory but its still a no go

then again, im not sure what they mean by turns, if they means turn the needle 180 degrees or a full 360 degrees. As ive seen guys do 180 degree turns and count that is a 1, 2, 3 on their needles but ive also seen em do 360 degree ones or dont know if thats what the factory wants.