BlakeRC

Truck is a RedCat Volcano S30. Rebuilt the SH .18 engine with new Fast Eddy bearings and new piston/sleeve as compression was very weak. Rod seemed good with no play so I left it original. Broke in the engine running very rich the way RedCat instructs. 1st tank - idle, 2nd & 3rd tank - up to 1/2 throttle figure 8, 4th tank - 3/4 throttle figure 8, 5th tank - full throttle (smooth acceleration) sprints back and forth. Always adjusting piston to bottom center at the end of the run and allowing 15 min cooling between tanks.

Brand New Glow plug installed before engine break in - O.S. No.6 Short Body Standard Glow Plug "Hot"

Yesterday I decided to tune the engine both high speed and low speed needles. Carb and idle screw were perfect at about 1/8". Truck idled great and didn't stall during runs. Best its ever ran. I leaned out the low speed needle until fuel line pinch test resulted in the proper rise in throttle for 3 seconds before stalling. Then I started to lean out the high speed needle. Still getting a considerable amount of fuel/smoke from the exhaust. Truck ran for a full tank with zero issues. I let cool for 10 min, refilled and it didn't start. Glow plug is completely dead.

Was this glow plug life premature because of the super rich break in process or am I doing something wrong? Wrong plug, still to rich, too lean? This is plug 3 thats burned out.

Thanks
Blake

1995 Monster T

You didn't break engine properly. You should have broken engine in at idle for 6-8 tanks then slowly drove truck as instructed only adjusting high only first then the low. last if needed. Use a new plug OS #8 and fuel with 14-18 oil lube for long engine life. and try again.

BlakeRC

Okay I haven't come across that set of break in instructions before. Is that from the motor manufacturer SH or just common practice? I followed the recommended instructions directly from Red Cat. Low and high speed needles were first set to factory location (flush to valve stem on low speed / then turned in a 1/2 turn) (flush to valve stem on high speed / then turned in 2 turns). Then before running them I backed them out some to richen. You're saying I should have only richen the high speed needle? Is running too rich what probably caused the plug to die prematurely? I am using 20% VP fuel in Vermont. 14-18% is a better mix for the engine/climate or just better for break in? Is the #8 plug better for this specific engine, just break in, or all around? Better to run rich or lean?

Do you think the motor was damaged as a result of my break in procedure?

Roelof

There are 1001 way to break in and all work. Yes, starting with idle is always good but for sure no must. Please, stop scaring people doing it wrong.

I would take of the heat and look into the combustion chamber and on top of the piston if some brown colour is showing. After that less it should not be much but it must be there. Next question is with the rebuild if you did put back all the headshims.

BlakeRC

I will have to get a temp gun as I do not own one currently. Sounds like this is a very popular way of determining if the engine is running properly. What temp range should I be looking to be in (140-180 degrees F)? I will check for brown on the combustion chamber and top of piston. Are you saying there should be some present or that if its brown that means its a potential problem? I did put the single shim back under the cooling head. It was just 1 however. Should there be more?

Thanks
Blake

Roelof

Depending the kind of oils in the fuel the color will show up on the piston/chamber and can be light brown up to full black. If it has spots or looks like it is sandblasted then there is a too high compression and that will ruin plugs. If there is dirt on top of the piton then you have to check all internal parts, something could be broken.

Regarding a temp meter, there is no default temperature, every engine (even a same model) will have its own correct temperature. It is more about tuning the engine right and then get the temperature and keep that one as an indicator.

BlakeRC

Trying to post some pics of the piston/chamber but it looks like I don't have that ability yet as a new member. Looks very clean though with very little discoloration and no dark spots of any kind.

BlakeRC

When reading other threads it seems plugs can die from running too lean and too rich. Is this correct? My engine certainly has not been run too rich since rebuilding and installing new plug.

token

Break-in is typically hard on a plug. I've always been told to change the plug after break-in. You could have also been to lean on the bottom by starting your tune there. The amount of fuel going through the highspeed needle can change the low speed settings.

Roelof

It does look good, no spots and there is a light brown color that will get darker after some real use. I also do not see any dirt. So ye, can be from the rich setting or maybe a bad balance between HSN and LN causing a lean spot somewhere.

1995 Monster T

You defiantly ran it to lean to fast. Engine temp will vary with different brand fuels. I think VP fuel is crap over priced fuel. Use fuel with 14-18% oil lube. I run Omega.17%oil lube now. Set the carb back to factory settings put a new plug in Assuming you put the engine back together right. and run it at idle 4-5 tanks then lean out the high 1/16 turn and start driving slow. If the low is sluggish 1/8 turn max if it doesn't improve leave it alone. breaking in slow is best.

Roelof

OOOOOHHHHHH NOOOOOOOO!!!!!! Him again with the 18% oil advise as the only good advised fuel.

And tell me, why are you blowing plugs when going too fast to race tune, never had that. Do not tell the tight pinch will give a higher compression. A just broken in engine has made the piston and sleeve a perfectly match, new they aren't. If you go too lean too fast then you will get scratches on the piston with the chance it stalls due the tight pinch at the higher temperature. Also none of that did happen.
Also I do not understand why now go back to some tanks idle while it already had run higher revs at the 5th tank, the idle will not do much.

BlakeRC

I have an OS #8 plug (medium temp). Should I try that and retune? Both the OS #6 and #8 are referred to as 'short body standard plugs'. Would this be correct for my SH .18 engine? I have come across some literature that states the SH motors need a long plug. Has anyone else seen this? Does anyone have a picture or good description of how far the plug should enter the combustion chamber of the motor?

The bad plug does not appear to be discolored but the coil is on the white side..

When you say too lean on the bottom what are you referring to? The low speed needle?

Thanks
Blake

BlakeRC

What is the proper balance between high and low speed needles? For a motor that has been rebuilt and broken in, with both needles set back to factory defaults what should the process be? I'm under the impression that the pinch test determines if your low speed needle is set correctly (revs up for 3-5 seconds before stalling). And to see if the high speed needle is correct you test your mid-full throttle performance. If it accelerates smoothly without cutting out or bogging down then its good. If it bogs down then its too rich. If it cuts out and stalls or there is no smoke then its too lean. Does this sound correct?

Thanks
Blake

1995 Monster T

Start with the factory settings and see how it drives. You shouldn't touch the low. Start with the high needle and adjust 1/16 turn at a time per tank and see what happens Make sure your fuel system has a fuel filter. Max turns 4 on high and you should still be fine. Fuel with more oil lube will give the engine better protection and allow for a cooler engine and give you basic tuning ability. Stay away from Race fuel with less that 14% It's going to tune different, and you will find it harder to tune.