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head is smoking....

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is the engine going to actually "explode" or is that just a saying? I don't see how heat effects the metal piston.
How much are pistons and sleeves? what will happen when it breaks?
I ran it again tonight and highest it got was 276. It bogs like a sunofabitch, bad accel but when it gets going man it rules.
I'm just mad that my friend can't get his to shift to second and it has awesome excel though.

Isn't $30 kind of rediculous for something that checks the temperature...
 
When they start going bad they wont hold a tune worth a poop, and eventually just wont start anymore. No they dont "Explode" the worst I've seen was a rod though the block but that was only once.

Checking the temps in something that needs to be done in this hobby, and also is AWESOME to help get the correct tune. So $25-$30 is a great investment considering it protects a $100 (easy) investment (the mill).
 
6_dman_6 said:
is the engine going to actually "explode" or is that just a saying? I don't see how heat effects the metal piston.
How much are pistons and sleeves? what will happen when it breaks?
I ran it again tonight and highest it got was 276. It bogs like a sunofabitch, bad accel but when it gets going man it rules.
I'm just mad that my friend can't get his to shift to second and it has awesome excel though.

Isn't $30 kind of rediculous for something that checks the temperature...
Click to expand...

1: No they don't literally explode, they just sort of die slowly..unless you hold it WOT till it pops....
2: the metal in the sleeve is brass the piston is chromolly or some soft steel....the brass sleeve will expand and contract w/ heat...you want that to happen to some degree or your piston will be slammed into a tappered hole w/ every stroke, wearing out the edges of the piston head....if the temperature rises too much the metal will expand beyond what you want it too...when it cools it's memory will return most of it to original shape but 2 things happen...it will still be more expanded now that it should be due to excess heat...and 2 it is more brittle now....metal has been thinned and super heated and super cooled...it just happens
3: Piston and sleeve and conrod for 2.5 runs about 70-85 bucks....just save more and buy a better engine.....
4: when it breaks........you'll know.....anything from blown seal to mangled conrods......or like andy said through thte case....seen that too......
5: I run 2.5s around 250-260....they don't last long at that temp though but you get some evil power from a cheapo engine......276 if it's only been spiking at th at you're OK for a while but if it's been peaking like that alot...start saving......
when you say bogs...it is a fat gurgly sound or a too lean , not getting enough fuel kind?
if it's the fat sounding one then I'd say you have 2 issues possible.....your too lean on top and too rich on the bottom......real far off if your bogging down low and still running high temps......second is you might have an air leak.....does it idle solid or rev up and down?
 
Plaidfish said:
1: No they don't literally explode, they just sort of die slowly..unless you hold it WOT till it pops....
2: the metal in the sleeve is brass the piston is chromolly or some soft steel....the brass sleeve will expand and contract w/ heat...you want that to happen to some degree or your piston will be slammed into a tappered hole w/ every stroke, wearing out the edges of the piston head....if the temperature rises too much the metal will expand beyond what you want it too...when it cools it's memory will return most of it to original shape but 2 things happen...it will still be more expanded now that it should be due to excess heat...and 2 it is more brittle now....metal has been thinned and super heated and super cooled...it just happens
3: Piston and sleeve and conrod for 2.5 runs about 70-85 bucks....just save more and buy a better engine.....
4: when it breaks........you'll know.....anything from blown seal to mangled conrods......or like andy said through thte case....seen that too......
5: I run 2.5s around 250-260....they don't last long at that temp though but you get some evil power from a cheapo engine......276 if it's only been spiking at th at you're OK for a while but if it's been peaking like that alot...start saving......
when you say bogs...it is a fat gurgly sound or a too lean , not getting enough fuel kind?
if it's the fat sounding one then I'd say you have 2 issues possible.....your too lean on top and too rich on the bottom......real far off if your bogging down low and still running high temps......second is you might have an air leak.....does it idle solid or rev up and down?
Click to expand...
I couldn't seem to figure it out. What it does it when I hit the gas it SLOWLY excels then it just takes off.
 
that's too rich....it's got loaded fuel and it's going to flood if you leave it alone right?
if so then you have 2 screws to check
1: set your idle screw....leave approx. 1mm opening.....this will limit how far your carb closes when you sit at neutral or apply brakes.....(note: applying brakes should not allow the carb to close anymore than at idle, if this is the case you need to reset your linkage before making any adjustments)
2: after idle screw is set, lean out your LSN.....let it run for a few mins doing some short bursts of 3/4 throttle...then let it sit for a second....pinch the fuel tube right before it enters the carb closed...if it leans out and starts to die in about 5 seconds you're good to go......if not then run it around a little bit more and repeat until you're starting to lean out at 5-8 seconds.....then go back and tune the top end for temp.....you will have to adjust the LSN again after the top end is done......I do it this way whenI don't know the factory settings......I never remember them anyway so to me it was just easier to do it like this.....takes longer but you'll never be stuck w/ a crappy tune.....and as far as the temp guage goes....you NEED it until you can tune by ear/performance..... it will save you many many dollars in this hobby.....and if you can get the raytek one....it's twice the price but it makes learning oh so F'ing nice
 
Sounds like the LSN is set too rich. Once you have the truck running at a good temp (250-260) after a couple of full throttle passes, turn the LSN (low speed needle) in an 1/8th of a turn at a time and you should see the acceleration pick up. You can tell if ithe LSN is too rich or not by pinching the fuel line. If it revs up and shuts off after 2-3 seconds you're good. If it keeps running, it's too rich.

If you like running it on the lean side, andthe temps are constantly around 325 (or over 280) invest in a good aftermarket head like ACNCM. It will keep your temps down and you'll have a happy 2.5 that will live for quite a while.
 
careful w/ teh ACnC head...temp your case instead of the block.....that thing cools so fast you can over heat it and still get low head temps......I see it happen every weekend I go to the track now....it's a great head but be aware you need to read a more stable temp spot.....
 
Plaidfish said:
careful w/ teh ACnC head...temp your case instead of the block.....that thing cools so fast you can over heat it and still get low head temps......I see it happen every weekend I go to the track now....it's a great head but be aware you need to read a more stable temp spot.....
Click to expand...
Man, my friend runs his car WAY rich...because it accels awesome...but something is wrong with the transmission or something because it doesn't hit second gear.
He bought a new head and it cuts out after a few highspeed runs and the head is always 170 I'm sure the engine is MUCH hotter then. I have to tell him to check the block....
But he broke his gas tank and some plastic pieces so it'll be 2 weeks before he drives again.

Plaidfish said:
that's too rich....it's got loaded fuel and it's going to flood if you leave it alone right?
if so then you have 2 screws to check
1: set your idle screw....leave approx. 1mm opening.....this will limit how far your carb closes when you sit at neutral or apply brakes.....(note: applying brakes should not allow the carb to close anymore than at idle, if this is the case you need to reset your linkage before making any adjustments)
2: after idle screw is set, lean out your LSN.....let it run for a few mins doing some short bursts of 3/4 throttle...then let it sit for a second....pinch the fuel tube right before it enters the carb closed...if it leans out and starts to die in about 5 seconds you're good to go......if not then run it around a little bit more and repeat until you're starting to lean out at 5-8 seconds.....then go back and tune the top end for temp.....you will have to adjust the LSN again after the top end is done......I do it this way whenI don't know the factory settings......I never remember them anyway so to me it was just easier to do it like this.....takes longer but you'll never be stuck w/ a crappy tune.....and as far as the temp guage goes....you NEED it until you can tune by ear/performance..... it will save you many many dollars in this hobby.....and if you can get the raytek one....it's twice the price but it makes learning oh so F'ing nice
Click to expand...
I'll try both of those suggestions out thank you. I will go for sound tonight then tomorrow I will use my friend's temp gun for perfect tuning.
 
raytek is like the standard...I wouldn't use the duratraxx one uless it was all I had in an emergency.....even the raytek mini isn't all that exact......check it against one of those exergen sensors......the higher the temp the more the drift in temp is......
 

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