<VV> one side running hot

[djtcz at comcast.net]

----- Original Message ----- 
Message: 4 
Date: Wed, 22 Sep 2010 15:21:49 -0400 
From: 4carbcorvair < 4carbcorvair at gmail.com > 
Subject: <VV> One side running hot, carb issue?? 
To: virtualvairs at corvair.org 
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< AANLkTi=S_rm-MCJyib7NFCHTMVsOFXj3i7boN=ceit1u at mail.gmail.com > 
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snip ... The issue, one side seems to be 
running hot. I put my laser/digital thermometer gun on the right side 
exhaust (furthest back), where the tube meets the log and get a reading in 
the 220 degree range at idle after about 20 min. Now, the left side. I get a 
reading of about 420 on the most rear exhaust measured at the same spot. The 
guage in my Corsa reads 275ish at idle..... I am having a bit of a 
sputtering problem, which I believe to be a carb issue. I'm thinking I may 
be running a bit lean on that side? I've got number 52 jets in the mains, 
50's in the secondaries. Any thoughts or opinions? 

-- 
Ronnie 

=========================================================== 


An exhaust manifold barely about boiling water? And cooler than the cylinder head? Seems odd. I think I've verify the temp measurement other ways, and probably still use other criteria for making tuning adjustments. 


Main jets don't normally have much effect on idle mixture. 


"Laser" aimed infrared thermometers report temps based on an assumed "emissivity" which is a characteristic of the surface of an object. Some high end instruments allow entering different values of emissivity, in the unlikely chance I actually know the surface emissivity, or, as would be more likely, tweak the "laser" to match a reading made with a contact probe, etc. Predictions of better cooling when surfaces are painted flat black are also rooted in beliefs about "emissivity." 
But paint color alone is not always a good indicator of what its emissivity will be. 
http://snap.fnal.gov/crshield/crs-mech/emissivity-eoi.html 




http://www.raytek.com/Raytek/en-r0/IREducation/EmissivityTableMetals.htm 


Dan T