Temp gun never measures more than 210F at glow plug

Welcome to RCTalk

Come join other RC enthusiasts! You'll be able to discuss, share and private message with other members of our community.

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.

bobthebob

RCTalk Racer
Messages
88
Reaction score
30
Location
Hillsboro OR
RC Driving Style
  1. Bashing
I've got a pretty new HPI Savage X SS k4.6, Almost a gallon through it now. I am wondering if I am still running it way too rich, or if my temp gun isn't working, because I've never measured the temp at more than 210F "at the glow plug", I'm pointing the temp gun either right on the glow plug or right around it point down through the top of the cooling fins. Is this the correct way to measure? I can do wheelies and I think my top speed is around 35-40mph so I feel like my temp should be hotter. What's more likely, temp gun way inaccurate, or my temps are still just really that low? The air temp is 50-65 degree around here so maybe it's just staying really cool?
 
Do you have matches, lighter or the means to make fire? If so, point it at that. Should go higher than 210F. Or if you take the glow plug out, plug it into your heater, the coil will be far above 210F and you can try and point it at/near the coil while it's red hot.

Typically, you want between 210-250 when the ambient temps are 70-85F or so. 210F @ 50-60 ambient probably means your closer to 220-225. How and where your temping is where/how I do it.
 
Temps are also just a safety check. If it's launching well from a dead stop and ripping at WOT, you're still good. Some engines just won't run unless they're above 250, but that doesn't mean they NEED to be there in order to perform.
 
Keep in mind the ambient temp as well... I don't know about where you are, but in the northeast, it's getting cooler, quick! That will drop your over all running temps.
Def can test the temp gun for some accuracy with boiling water and with ice cubes/ice cold drink.
I know as it gets colder here, I need to adjust my settings. I haven't had to switch out to a different glow plug or anything, but that can effect the temps as well.
I totally agree with all above statements. As long as you're getting good performance, it doesn't seem to be ripping thru tanks of fuel at an alarming rate and you're getting reasonable amounts of smoke from your exhaust, it sounds like everything is ok.
 
Thanks for the replies. I'm mainly just curious, I've had nitro planes for a few years and never done a temp check because I don't think the engine manuals suggested it. Also when adjusting the HSN I was having trouble figuring out if I was on the lean end or the rich end so since the manual gives a temp baseline I was hoping I'd be able to tell if I'm still too rich from the temp. In a driving session a few days ago I suddenly wasn't doing wheelies anymore after leaning a bit so I thought it was too much, but then I cranked it back richer and it didn't seem to improve anything. May just have been losing traction. Then a couple days later I leaned it some again, and I'm back to getting wheelies. I still think it's a bit on the rich side though.

It's pretty fast but I'm not sure I'm really hitting top speed, I feel like the RPM's should be getting slightly higher or it should be accelerating a little faster. Not sure if I should try the HSN again or just start adjusting the LSN once I'm up to operating temp again. I think my LSN is basically still at break in setting, although I accidentally turned it a few times then back again when mistaking it for the idle adjustment so I don't know exactly where it is other than roughly flush with the case. Engine has almost a gallon through it now.

Do you guys adjust the HSN while running the truck to see how fast it is, or just floor it while on a bench and listen for peak RPM by ear?
 
My adjustments are made while running... It gets a lot easier to make those adjustments when you're closer to dialed in to start as well as knowing your rig.
I would recommend checking your manuals just to refamiliarize yourself with the baseline settings for your engine. Maybe start from there. If you have accidently moves your idle setting, be sure to start there. That is ALWAYS the beginning point when tuning. From there, basically baby steps, little adjustments at a time, always keeping an eye for a healthy stream of smoke from the exhaust.
Just to check, have you gone thru the propped break in procedures on this motor? I don't know anything about airplane engine break in so I don't know if it's different. Break in is important for these engines for sure tho.
I will be happy to help you out as best I can with whatever I can tho.
Propper setting for an idle gap is aprox 1mm opening when looking thru the carb throat. You can use an Allen wrench to gap it.
 
My adjustments are made while running... It gets a lot easier to make those adjustments when you're closer to dialed in to start as well as knowing your rig.
I would recommend checking your manuals just to refamiliarize yourself with the baseline settings for your engine. Maybe start from there. If you have accidently moves your idle setting, be sure to start there. That is ALWAYS the beginning point when tuning. From there, basically baby steps, little adjustments at a time, always keeping an eye for a healthy stream of smoke from the exhaust.
Just to check, have you gone thru the propped break in procedures on this motor? I don't know anything about airplane engine break in so I don't know if it's different. Break in is important for these engines for sure tho.
I will be happy to help you out as best I can with whatever I can tho.
Propper setting for an idle gap is aprox 1mm opening when looking thru the carb throat. You can use an Allen wrench to gap it.

I did start at factory settings, and broke in the engine more or less according to the manual. The high speed needle is much much leaner that it was at break in, but probably still less than 1/2-3/4 of a turn clockwise total. I cranked it leaner very conservatively over 5-8 tanks and now I'm at the point of fine tuning basically. The factory setting for the low speed needle was a bit confusing to me though, it said it should be flush with the case, but to my eye it was about .5mm past the case (on the rich side), and its still in about the same place, but I can't be totally sure because again I accidentally moved it both ways and since the truck is running pretty well and reliably now I hesitate to touch it again until I know the HSN is where it should be for a broken in engine. I wasn't sure if that needle was adjusted wrong from the factory, or they meant "nearly flush" instead of flush.

I also have adjusted the idle screw down a little bit from factory idle because it was too high, especially after leaning the HSN to where it is now. I do have a pretty good idle but it will normally stall if I let it idle for more than 30-60 sec without gunning it a bit. I do have a lot of smoke at full throttle but am not sure how much less it could or should be to be optimal. Using Traxxas 20% fuel if it matters.
 
Before I get too far into all of this and because you already have experience with nitro, let me point you in this direction. This should answer most of not all of your questions and guide you thru what is and is not expected. This guide should help you get on your feet. I am not trying to pass you off by any means. Just think rather than rewriting this...
https://www.rcnitrotalk.com/forum/t...ips-and-tuning-flow-chart.60832/#post-1039985
Don't be afraid to make adjustments... They are ALL 'undo-able' . It's a good idea to keep track of what you are changing so you can bring it back but if you get totally off, setting back to factory will always get you close.
The way you are describing your low speed being so far over flush( flush being a common stock setting) sounds like you're rich, above and beyond. The way you're describing the dying problem reinforces the thought. Check out this chart and the rest of the post. Let me know what you think and how I can help you out further.

https://www.rcnitrotalk.com/forum/t...ips-and-tuning-flow-chart.60832/#post-1039985

Not sure why that link came out funny... Sorry bout that. Fat thumbs, small buttons I'll bet! :hehe:
 
Btw, as far as the optimal smoke for hsn setting... You want a steady stream, not profuse by any means. It should be light, but steady. You will get a feel for what is 'right' by getting your peak speed while maintaining that stream of smoke as well as by checking your temps. You should take it for quick lengths of of time, short runs, bringing it to top speed. Note the smoke is steady and with each adjustment, see that the top speed is increasing. Keep the temps within those already specified. You will reach a peak where the temps are getting too high and/or the smoke isn't steady. (this will likely go hand in hand so to speak) From that point, dial it back down to where the temps are steady and that the smoke has returned to a light but always present stream. From that point, start to increase your run time, still checking for all above. Again, maintaining your temps. Keep in mind that these runs shouldn't be wide open for the entire run. These engines (the off road nitros) are not designed for full throttle constantly. Also keep in mind that As you're dialing it back, if you intend to run in grass for instance, this will put more strain on the engine and will make it run hotter than running on road. You are better to dial it back down a little more and be in the safe side. The more you run, adjust and 'learn your car' the easier it will be to recognize where you are set and where your motor is happy.
 
Cool I'd read some of that but not all of it before, will reference. Thanks for the tips.
 
If unsure ,you can also do a water drop test!

Just drop a couple of droplets of water on the head ,if it boils away as soon as it hits the head ,
then its too hot!...:cool:
 
How are you making out? Did that get you straightened out or do you think you'll need a few more pointers? Let us know, we all work together to help out!

The water test does work but where you have the heat gun, you can actually 'take notes' just recording what you did with your settings, the temps and how it affected your performance. This will Def help you narrow down what you need to do next and to help eliminate settings that you've already tried.
 
Last edited:
Doing well! Still haven't figured out if my temp gun is accurate or not but I had to put a new glow plug in recently and the engine is the best it's ever run.
 
Back
Top