Hey guys,
I did a search and got nada on this, so I figure I'll post it here:

I was finalizing my order for gauges, and I think I'm set on the Autometer Sport Comp electrics for Exhaust Gas Temp (EGT), Oil Pressure, and for now Cylinder Head Temp (CHT). The plan was to move that one to the glove box when a boost gauge goes in.

But a guy I know at work who is really good with cars only recommended the EGT and Oil Pressure. He said that the CHT won't give you a good "Oh Crap!" warning like the EGT will. So I'm reconsidering . . .

Also, I was confused about the installation: it looks like the probe goes in as a washer to the spark plug, but they also mention drilling and tapping the head. Any ideas on this?

thanks,
ac

 

The CHT isn't necessarily an "oh crap-o-meter" but instead a different way of seeing problems. If you have too far advanced timing and are detonating, but not hearing it because of engine noise, then you can get very cool 1100-1200 degree EGT readings (fairly cool) while your cylinder head approaches thermonuclear meltdown.

Bad bad bad...

To mount the CHT, I removed the engine hoist bracket right near the steering pump. It's the big "loop" with a bolt stuck in the head. I removed the loop and the bolt and the autometer temp probe that I had was just EVER so slightly larger than the hole. Perfect! I tapped it for the proper threading and it fit the first time.

It does heat-soak a little bit from being on the exhaust side of the head, so a typical/normal reading seems to be around 225 when fully warmed up and running good.

I've seen it hit 250 before on a hard 0-110 run -- EGT's at the time were sitting at 1450 so it may have still been heat soak.

-Red-

 

What about their recommendation of using the probe as a spark-plug washer? I downloaded their instructions (Autometer's website is pretty cool) and that's exactly what they recommend doing.

Seems to me that would upset spark plug "gap" (I know not the actual gap, but how far it sits into the cylinder crown).

If I'm wrong, please let me know. But yeah, that hanger bolt location definitely seems like a good non-intrusive location.

thanks,
ac

 

You got the exact same autometer gauge that Joel did then, which can only be decribed with about fouteen of the choicest explicatives known to any good drunken sailor

So rather than go through all the explicatives wink.gif I'll just tell you what is actually wrong. We found that if that little loop is in anyway grounded, the meter would go totally insane. We first thought it was a problem with the little black sender box, so we sent it back.

The second one arrived and it did the exact same thing. We played with supplying it different voltages, different grounding points, isolated grounds, etc. We called the place he ordered it from to ask WTF and they couldn't help us.

We eventually thought of the possibility of perhaps the ring being grounded is messing it up, but that's totally against common sense. Really, if grounding the ring screws up the meter, why would they make it of bare conductive metal? rolleyes.gif

So the somewhat-long answer is, you have to find a way to make it non-conductive, make that non-conductive layer stand up to the load of being "tightened" down and also somehow make it thermally conductive. We ended up using pieces of my T-shirt tongue.gif

We also never found a way for that loop to fit around the spark plug and NOT get stuck in the "spark plug hole" on his Civic. Let me tell you, the depth of a Civic Si plug in the head is WAY more shallow than the depth of the plugs in our BETA heads.

Send it back while you can, buy the one that comes with the little screw-in connector that looks kinda like a cable (75-ohm) female recepticle (the one in the wall). Those others are a ROYAL F'ING PAIN IN MY POSTERIOR!

Hope that helps a bit smile.gif

-Red-

 

Come on Red...tell us how you REALLY feel about those thing! *lol*

 

well, I didn't buy it yet, so bullet dodged!

Thanks for the advice. I'll be on the lookout for a better one (or a different thermocouple version)

I am going to wait for confirmation of the gauge pillars before ordering the gauges anyway.

thanks again,
ac