Author Topic: Running Temperature  (Read 1432 times)

jbru34

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Running Temperature
« on: July 16, 2007, 09:59:49 AM »
I have a 350 with a bored out jug (can't remember the size). The melting point on the piston is said to be 1400 degrees.  My EGT gauge is saying i'm hitting 1250 and rising.  I let off the throttle right at that point.  I'm hitting 1250 only after opening her up for a few seconds.  Is that running temperature correct?  Could my EGT gauge not be correct?  Any feedback is appreciated.

-Jesse
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BigMike

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Running Temperature
« Reply #1 on: July 16, 2007, 11:36:36 AM »
I was told that 1300 degrees was the point at which I should think about letting off the throttle and letting her cool down.  I have an 81mm Wiseco.  Your estimate of around 1400 degrees sounds reasonable.

Mike

jbru34

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Running Temperature
« Reply #2 on: July 16, 2007, 07:56:21 PM »
so are u saying my temperature is right and that i just can't open up the throttle for a long period of time??  (by the way i do have a radiator on the engine)
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turbotexas

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Running Temperature
« Reply #3 on: July 24, 2007, 09:19:51 PM »
You should ignore the egt until you take some plug chops... Every egt will read different and is only a reference point AFTER you have your carb properly jetted... Mine never gets above 1175... on steep hill climbs...

jbru34

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Running Temperature
« Reply #4 on: August 14, 2007, 09:12:09 PM »
i'm still learning...whats a plug chop?
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nuke em

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Running Temperature
« Reply #5 on: August 17, 2007, 07:20:21 PM »
The plug chop(Nuke Em style).... you basically run the engine for a fairly long straight away at a steady throttle position (1/4, 1/2, 3/4, WOT), then hit the kill switch and coast to a stop. Next, hop out and pull the spark plug and "read" the burn color/pattern. Light grey or white = way too lean and you will sieze a piston very soon(1400+ deg),  dark tan to milk chocolate is usually considered about right (+ or - 1200 deg),  black and wet with fuel means too rich(usually 1050 degrees or less).

This is my personal finding at my high riding altitudes. There are several much MUCH better jetting/plug chop explainations on other websites(Yellowdog racing for one).

The distance of you EGT probe from your piston edge will also give different readings. I run my probes about 5" from the piston edge. I also run my engines fairly rich(1200-1250 deg max) at 32:1. I would rather be a little down on power than get every scrap of power and have to rebuild the topend fairly often, but thats just me. :wink:

Any more questions, just ask...I love this stuff!

Gary