EGT location question, Jake? Options

[SpecialK]

My '73 (carbed/Web 86 cammed 2.0L) will be sporting 4 EGT probes and 4 CHTs (one for each cyl., got one hell of a deal on them plus I read the "dropped valve seat" post (IMG:style_emoticons/default/icon8.gif) ). I've got one Westberg combo EGT/CHT gauge and a 4-way switch. The mfg. says to mount the EGT probes 6" from the exhaust port, but I'm running heat exchangers. If I mount them at the end of the heat exchangers just before the muffler flanges will I render them pretty much useless for tuning purposes, or is the temp drop at that end of the exchangers insignificant (again, for tuning/monitoring purposes). I'm afraid if I install them up by the heads, they'll be vulnerable to road debris, i.e. - semi retread rubber (A.K.A - road gators), critter's, assorted crap that flies out of Redneck's trucks w/o tailgates, etc...

Also have an A/F gauge I was going to install, but that would probably just be overkill (IMG:style_emoticons/default/rolleyes.gif)


As always, any input is greatly appreciated (IMG:style_emoticons/default/beer.gif)

Kevin

[ChrisFoley]

They will be much more accurate if you place them before the heat exchangers. You won't need the leads to be so long either.

[ablose58]

(IMG:style_emoticons/default/agree.gif) With racer chris,will definitely be more accurate (IMG:style_emoticons/default/smilie_pokal.gif)

[cha914]

If you had headers with the stub pipe design, could you sandwich the EGT probe between the flanges, or would that cause too big of an exhaust leak? I have never seen one of the probes in person, but they seem pretty small in pics.

Tony

[Slowpoke]

What's important with EGT probes placement, is their location. If it's too close the the exhaust valve, you get good measurements but short probe life. Too far from the exhaust valve you get good probe life and low readings. I've never heard of probe placement closer than 2-4 inches. If the instructions say to place them 6 inches away, I think that is kind of far away, so, either they are lower quailty probes, or/and, the gauge is calibrated for their placement that far away. Do you have fast acting probes? Can you use a better quaility probe closer to the exhaust valve? All good questions to ask the company that made it. ALso, check with them to see if you can cut the wires going to the probes. Lower quaility instruments don't allow you to JUST SHORTEN any leads to the probes. This makes for a sloppier appearing installation. (IMG:style_emoticons/default/smile.gif)

[SpecialK]

Well, the gauge and probes are FAA TSO'd, which I guess is the civil aviation version of "milspec" (hopefully fairly accurate). So I guess I should stick with the mfg. recommended placement (IMG:style_emoticons/default/sad.gif) . The leads are 48" and can be cut with out having to recal. the gauge. They sell lead extenders that can be added to the probe leads, but after 10' (?) it'll start affecting the gauges accuracy. Maybe I should do some testing with my digital pyrometer placed at both locations to see how much the difference really is (IMG:style_emoticons/default/idea.gif)