CHT-EGT-Spark Plug Wires...Get along?

TX7A · #1 04-17-2011, 11:25 AM

I'm having trouble finding a definitive answer in a forum search.

Can the EGT & CHT wires be run parallel and bundled together with the spark plug wires without goofing-up the readings?
And if they can't, can they cross each other?

I have a Slick mag & harness w/Dynon probes.

Thanks much!

Scott Hersha · #2 04-17-2011, 11:35 AM

Mine run together with no problems. I also have a Dynon. The spark plug leads are shielded, as are the CHT/EGT wires, so it shouldn't make a difference.

Walt · #3 04-17-2011, 11:37 AM

Not generally considered "standard practice" to bundle anything with the ignition leads. Will it effect the readings, can't say for sure but high tension leads can certainly be a significant source for noise.

RV10inOz · #4 04-17-2011, 04:33 PM

Keep them seperate. If for no other reason than when you come to service mags or do something else you will not want to bust into your probe wire bundles.

TX7A · #5 04-17-2011, 06:15 PM

Quote:

Originally Posted by RV10inOz

Keep them seperate. If for no other reason than when you come to service mags or do something else you will not want to bust into your probe wire bundles.

Between yours & Walt's suggestions, I think that's what I'll do. In my case, it's a choice of bundling it all together and making it look "pretty" or keeping it separate.

Thanks fellas' !

Geico266 · #6 04-17-2011, 06:53 PM

My IO 540 has all wires bundled togeather and I have replaced one may with no issues. Bundle away!

jjconstant · #7 04-18-2011, 09:10 AM

I had them bundled and my tech counselor told me to redo it to keep them separate. My understanding of his explanation was that the high voltage in the ignition wires might/could in some instances induce a voltage in adjacent EGT/CHT wires and that the voltages being measured in those wires was so small, any induced voltage would show up on the EGT/CHT instrument.

I also had people come in who disputed this based on their experience! It became one of those things where people who knew what they were talking about and had experience had differing opinions. In those instances I've tried to choose the path that has the potential for the least downside. Bundled=possible problem, unbundled=decreased possibility for problem. That being said, I have on occasion chosen to do an "informed dissent" where, despite people telling me the downside of a choice I do it anyway. I usually wind up redoing it later in private

Sometimes I just need to be contrary

Jeremy