Measuring temp - Question

[ratchet1974]

Savage X 4.6.

I have about 6 tanks of fule through it. Followed the break in procedure & have a couple questions.

I use this temp gun to take the temps:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96451

I take the temp by pointing the laser down into the cooling head by the glow plug after I do a quick full throttle run down the street & bring it back. When I take the temps, here's what I get

- about 190-200 degrees as far in front of the glow as I can
- about 220 on the front side of the glow plug, or just on the front edge
- about 230 just off of the back of the plug
- about 260 at the back corner of the head

Keep in mind, these are all inside the cooling head.

Question: Where do you think is the best place to take the temp ?

The thing seems to be running good & has a light trail of smoke when accellerating, but the bottom end still does not sound too clean when you accellerate. It has stupid torque (I love that) and can get all 4 wheels up off the ground (I put on a wheelie bar), with just a tap of the throttle. But under a smooth acceleration, it seems a bit hesitant & sloppy at the low end.

At idle, it does seem a bit rich, as it produces a very light smoke. Maybe I'll go in 1/8 tun in the LSN ?

Like I said, just asking the temp question, as I do not want to burn it down, as I'm ready to start some bashin around !

Thanks in advance

Sorry, By the back side of the head, I mean by where the exhaust comes out.

Thanks,

 

[Lessen]

Although, I've never seen much talk of where precisely around the glow plug is the best place to temp I would go with the "wost case scenario" reading... the highest temp you get.

 

[Rolex]

I just scan around and look for the highest temp INSIDE the head.
Forget about the reading you get at the exhaust manifold.

 

[ratchet1974]

Although, I've never seen much talk of where precisely around the glow plug is the best place to temp I would go with the "wost case scenario" reading... the highest temp you get.

Hey Lessen,

That's originally what I was thinkin, but I wasn't sure, as the back is by the exhaust & it would naturally be hotter, and because of the variation across the head......checkin off of the back of the plug is about 230, so since it's still kinda new, I'll leave it there.

It would be interesting to see where everyone stands on this. Checking on the plug is a bit hard, as there is not a nice flat surface - the more area the better with this type of gun.

I hope I'm not diving too deep into this :\

I just scan around and look for the highest temp INSIDE the head.
Forget about the reading you get at the exhaust manifold.

I'm not at the exhaust manifold, this is all arond the inside of my head. I was just surpirised to see that much variation.

Maybe I'll richen it up a bit just to make sure I'm on the safe side.

Thanks Rolex

 

[Lessen]

Yeah, there will always be quite a bit of variation in that small amount of space. I've always gone with the hightest reading.

 

[JessF]

The product description is a "non contact LASER thermometer" then goes on to say "Instantly measure temperatures in automobile engines or other machinery by simply pointing the laser."

the actual part doing the temp measuring is the "Professional quality, German infrared technology..."

it uses infrared just like the smaller Duratrax models we use. Don't be fooled by the mention of a laser, it's simply meant for pointing and not the part that actually takes the temp.

If you're pointing the laser at the plug, the infrared sensor may be pointing at the cooling head, giving you a false reading. The further back on the plug you measure the more exposure the infrared sensor gets and the truer your reading is. Forget the laser and point with the infrared sensor.

It's the same trick they use on those $50 distance-measuring tools you get at Hardware stores. The laser is for aiming, ultrasonic clicking does the actual measuring.

To get a proper lazer-measuring tool of any kind usually means spending $200 or more, with a few exceptions.

Your highest temp was probably the correct temp.

just my two cents.

 

[Rolex]

Great info, Jess. You nailed it with the laser simply being an aiming device.
I have the Raytek. Same device, minus the laser. I just scan around inside the head and go with the highest reading.

Lately that's been around 70 to 72. Room temperature.

 

[JessF]

It takes having to measure a 250,000 sq.ft. factory before you fully realize the importance of a proper laser measuring tool. I figured it would be the same for these temp guns.

 

[Scrogg]

Nope, point the sensor directly over the glow plug. Forget the laser. Listen to the engine, don't richen it up if it is blowing plenty of smoke and/or sounds rich. worry about the temps last.

 

[ratchet1974]

Point well taken guys.

I bought this tool in the past for a number of things & because it was pretty cheap. At first, I did a few checks, against a contact pyrometer. At 300 degrees, this thing was within 5 degrees. When I was about 12 inches away. but I never thought to look at different geometries / distances away.

Jess, I think you're correct. As I played with it a bit more today and can change my temp by rotating the gun with the laser pointing directly on the glow plug. In an area this small, I'll have to play around with it and see how I can consistently measure the temps by aiming the sensor & not the laser.

I guess it's better then no temp gun at all.

Sorry to get too off topic

By the way, this site is great. I used the flowchart in the general section, and it helped. The only thing that I'm still a bit concerned with is my low speed needle. After running few more tanks today, the mid range seems a bit rich (wet / crackly sound when just crusing at about 1/2 throttle - not quite to 2nd gear). It also takes a second when you punch it before it cleans out and goes. Now my temps seem ok, just under 250. Would changing the low speed needle have any effect on this in the midrange ?

Thanks guys.

 

[Rolex]

Leaning the LSN would give you the punch off the line as well as the RPMs needed to get you to the shift point quickly.
Lean it in VERY small increments, and run it around after each adjustment to give it a chance to clear out.
Keep a close eye on your temps since the LSN can alter them quite a bit if you go too lean. After half throttle, it's all up to the HSN for the best WOT running.

 

[Scrogg]

Actually the LSN controls fuel flow from idle to 1/4 throttle, after 1/4 throttle the HSN takes over.....BUT if the LSN is too rich it will cause the crankcase to load up with fuel causing your condition. So yes, lean the LSN. You may need to richen the HSN a bit if the temps start to rise.
After the engine gets around 3/4 to 1 gallon thru it, the midrange bog will disappear if you can't already tune it out.
BTW it's time for a new glow plug. ALWAYS throw away your breakin glow plug after 6 tanks. The microscopic metal particles that are a result in the break in process attach themselves to the glow plug element. Plus the rich running conditions of break in weaken the glow plug element. If that element breaks off it will ruin the engine. Cheap insurance to go ahead and throw it away.