Cylinder Head Temperature Gauge - Should I? & or Air Fuel Ratio

Update is that the cylinder head temperature gauge 'wires' do not fit in my cylinder heads.

The 'sensor' fitted over the thread in the spark plug easily enough, but there was no way the 'fat wire' would pass through the gap.

On my heads there is a ridge just above the spark plug threads, the sensor ring filled that ridge perfectly, but there is no gap left big enough for the sensor wire to pass.

I even bought ngk plugs which are meant to be slightly smaller above the threads than Bosch.

On there image there is plenty of room, but there isn't on my heads.

Hopefully you won't have the same issue i did

 

I know its sacrilege but what somebody rep

I know when I was playing around with thermocouples on my stock VW T1 heads , I found the same problem but as my stuff was a bodge I didnt say anything, and side stepped the whole issue using Mexican castings that have an M10x1mm threaded hole near the exhaust port at one end of each head. So I screwed my sensors in there.

I know its a bit scary, but one person on the Samba reported basically putting an old spark plug in the hole and then basically drilled down beside the spark plug body to make a groove for a wire.

On the other hand, if they are Type K thermocouples, the bead thermocouples by themselves are only a couple of pounds each from China. And you just find a place near the spark plug where a blob of JB Weld will fit between the fins, and glue the bead thermocouple into place.

 

Yeah i missed the opportunity to 'cut' holes out of the heads so the wires fitted.
I think there is a good photo of someone doing that earlier in this thread.
I may try and source some 'thinner' thermocouple wires.

 

I seem to recall that peeps have taken a dremmel to the material around the plug to make room for the tab. Mike's suggestion of bonding the thermocouple to the head seems good. It's just a case of getting a good fix to the head isn't it, not necessarily about getting it under a plug?

 

dremmil is the way i would have thought (is the engine back in Paul?)

 

End of day just go steady ...there not that fast even when pushed .

 

@Deefer66 post is a good example of making the sensor fit.
My dremmel / cutting etc opportunity has been and gone as the engine is now back in.
You can see how 'big' wide the sensor is above the ring, on my thermocouple

 

I'm going to cable tie a small person under the bus, they can point an infra red thermometer at the cylinder heads & can shout out the readings using a walkie talkie

 

@PanZer attaching the sensors to the rocker covers will only tell you the rocker cover temperature, which isn't an indication of anything.

I've seen some people attach them to the exhaust bolts coming out of the heads, but that isn't really giving you the cylinder head temperature

 

Works for me!...

 

FYI - A thread worth watching perhaps - Mofoco head issues - https://www.thesamba.com/vw/forum/viewtopic.php?t=757179

 

thanks Mike I'll take a look at it

 

Without having read it, no way on earth would I ever buy anything "Mofoco" had made. They guy has tunnel vision, he can't accept any criticism. He would argue black is white to defend his products. His market is Americans who buy his stuff because it's American which is enough to convince them that it therefore must be the best. I kind of approve of the patriotism but...

 

I've looked at thread now and it's the same complaints as it was when he started making them - the casting is terrible such that it's unusable, but he builds them up and sells them anyway - maybe he also throws away even worse ones! It'll be worth following the thread just for his reaction - it won't be his fault, anything but.
: popcorn:

 

You didn’t “hope” enough!
Looks like the same issue for me. Sorry you were the guinea pig!

Spark Plug shaft is 20mm. As is the outside of the probe ring.
Deepest recessed surround is 23mm. So that’s fine.
CHT Probe shaft is 5mm thick.
That ain’t gona work.

m5 bolt offered up won’t go in to the deeper recess but clears the 1st step:


So it really is just a few mm that needs cutting away at about 6mm wide for wriggle room.


First step recess is 7mm deep, but chamfers away, making even less metal needed to be cut out.

With the engine already built (Paul & my situation), can this be done (tinware removed) with the cylinder heads as they are? Put a 14mm bolt in the spark plug hole to stop debris entering.

Paul would have remove his engine...all just for a few mm of fettling.

How annoying.


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^this, if you've got Autolinea or (presumably) Mexi replacement heads. There should be a tapped boss on one (or both) where the temp sensor for the EFI goes. Much better than cramming a thermocouple down the spark plug hole.

 

If your engine isn't fitted then I'm sure it can be done.
No chance i'm removing my engine, only just got the bugger back in!

Mainline sensors have been brilliant, i told them it wouldn't fit, they have mailed me a label to return them and have given me a full refund

 

Do you mean this?


Empi heads.

Hard to show but looks like it has a large thread in it.
Same on the other side but towards the front. So one each side near #1 & #4.


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This one. M10 x 1.0, presumably for a thermistor type head temp sensor.