AT Racing 16% nitro racing fuel
 

Hi

Just wondered if anyone has tips for tuning engines for this fuel. I have previously been using a cheap fuel from my LHS with success.

I now have this AT fuel and my engines won't run for me, none of thm seem to want to idle on it... appreciate assistance.

Thanks
Andrew

have you checked for airleaks in the engine? if it hasn't been running for a while, it could have worn out o rings. if you have been using it regularly, it's probably an issue with tune...although in saying this, back when i was racing a few years ago i saw a few engines run (when hot) unstable on AT or sound very "pingy" when coming into the pits during race conditions. Maybe things have changed with AT, but that's something i remember about it...it could also be a lot of people were just not tuning the engines right though.

richen up the top end if it is bogging down out of corners after being ont he throttle, and richen the bottom end up a little as well.

if none of this works, go back to factory settings and tune it from here.

TomB:

The engine is a new STS and is still rich on HSN, i did try it in my Picco which i have been running for a while and it played up as well.

I might try some of fuel i was using to rule out an airleak.

Thanks
Andrew

good idea, keep in mind your old engines will be tuned to your old fuel so they may run fine. Engine's are not that tricky to tune, unless you are really out of the ball park.

make sure your fuel line isn't too short from pipe to tank. make line 1.5 times longer than pipe tip to header edge.

TomB:

Think I can rule out being a fuel issue, tried old blend and had same issues after some retuneing. I also was able to get one of the club members to try his hand and tuning it and it will only run for a few minutes and then flame out.

Starting to think compression is too tight still and it is just oiling up as I can't clear its throat enough.

Time to find where I put that old Picco and forget about this STS rubbish :)

Thanks again Andrew

new engines can be a little funy sometimes ay...maybe give it a litre or so it might stop being a pain in the arse;)

I've never experienced inconsistent idle with a new engine though, usually they idle fine

Bundy...

Under power... Air leaks

Wiggle the crank shaft, if it moves, your bearings are gone.
Check your fuel tank, if it's not providing pressure it will lean out
Check your Carby, if it's seated well, and the boot has no cracks or holes
Check your head and ensure it's clean and seated without pressure loss
(Put your ear up to it and turn t over by hand)
Check fuel lines for holes.
Check exhaust system for leaks.

If at idle..
Check your glow plug is seated and in good working order
Check your clutch after warmup and ensure it's not binding etc
Thrust bearing and clutch bearing could be stalling engine
Use a rubber band to retract the carby to ZERO and check your servo settings.


If all the above ok..
Warm the engine with a hair dryer etc.
Set a max 1mm Idle gap and then richen the top needle a whole turn
Try to start engine and lean the bottom needle until it does.
You may have to remove the plug and clear the flood if it's too rich
You should get to the point of an idle that lasts around 4 second before richening.
Gently throttle 1/8th the way and work the top needle without revving too high
Get a manageable top richness and set it on track.
Don't run it too rich nor too lean until it warms up then set the top needle slightly rich to ensure good fuel pressure.

Warmed up and circulating...

If the car over runs as you come off power after a long straight, you need to reduce the idle and lean the bottom a little more.
If the car comes off power well and drops to an idle nicely, then tune top to lean with trail of fine smoke, not too much as you cant compress liquids.

h

PS: AT Platinum is awesome fuel!

Add castor oil :nod:

according to sts engine setting,after completed the break in you need to take out 1 pc of head shim.
i facing before what you'r facing now,after i taken out the shim problem solved.

Update
 

I have taken the engine out to have a look for any signs of leaks etc. Everything seems okay, although the HSN was a little loose from me rotating the fuel nipple around.

Should i have changed the shims to suit 16% nitro as yet or wait till it is completely run in?

Thanks
Andrew

If a shim needed to be taken out , i would have done that before even starting the run-in

Ok i will look into what i should be running, guessed it would be easier to run in with less compression because of the extra shims.

Andrew

It will be easier to start in the beginning, thats about all.

That was the goal, too much strain on the poor starter box even after a few tanks on the run in bench.

Andrew

Its not so much to lessen the strain on the starter-box, even though it will.
It's so that the engine can 'pop' over a little easier because the compression is less. As normal, the p/s is really tight which makes getting it to run the first time is usually a real PITA! So adding a shim and taking out the plug a few turns makes it a little easier to start until its up and running, then you can tighten the plug and after a few tanks (once the pinch becomes less tight) you can then remove that extra shim and run where it should be running.