CHT probes

[flybynightkarmarepair]

How deep is the hole a "bayonet" type CHT probe fits into?

I don't like the spark plug senders, and want to drill the cast-in
boss for a CHT sender to suit the probes commonly available, but
without a probe in hand, I can't tell whether this is possible.

Anybody who can answer this question already knows what they look
like, but this forum serves an educational purpose for people other
than me, hopefully, so here is what I've talking about:
http://buyjpi.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=5050T&Category_Code=

[Kyle Boatright]

On Lycoming cylinders, I believe the CHT boss is already drilled and tapped.
I know they were on mine.

KB

"flybynightkarmarepair" > wrote in message
ups.com...
> How deep is the hole a "bayonet" type CHT probe fits into?
>
> I don't like the spark plug senders, and want to drill the cast-in
> boss for a CHT sender to suit the probes commonly available, but
> without a probe in hand, I can't tell whether this is possible.
>
> Anybody who can answer this question already knows what they look
> like, but this forum serves an educational purpose for people other
> than me, hopefully, so here is what I've talking about:
> http://buyjpi.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=5050T&Category_Code=
>

[CW Crane]

"Kyle Boatright" > wrote:

>On Lycoming cylinders, I believe the CHT boss is already drilled and tapped.
>I know they were on mine.
>
>KB

There is a pipe like fitting that is screwed into those holes. The CHT probe is
then inserted into the fitting and a BNC like cap compresses a spring that holds
the tip against the head (at least it was that way with the Grand Rapids EIS
that I used). The hole in the cylinder head is not very deep at all. Maybe 3/8
inch. It is really like one of those digital thermometers that you push against
your head inside your ear.

In another application I couldn't use the 14mm spark plug probe since I had 10mm
spark plugs and instead just put it under one of the head nuts on my VW.

CW
>
>"flybynightkarmarepair" > wrote in message
ups.com...
>> How deep is the hole a "bayonet" type CHT probe fits into?
>>
>> I don't like the spark plug senders, and want to drill the cast-in
>> boss for a CHT sender to suit the probes commonly available, but
>> without a probe in hand, I can't tell whether this is possible.
>>
>> Anybody who can answer this question already knows what they look
>> like, but this forum serves an educational purpose for people other
>> than me, hopefully, so here is what I've talking about:
>> http://buyjpi.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=5050T&Category_Code=
>>
>

[Michelle P]

flybynightkarmarepair wrote:
> How deep is the hole a "bayonet" type CHT probe fits into?
>
> I don't like the spark plug senders, and want to drill the cast-in
> boss for a CHT sender to suit the probes commonly available, but
> without a probe in hand, I can't tell whether this is possible.
>
> Anybody who can answer this question already knows what they look
> like, but this forum serves an educational purpose for people other
> than me, hopefully, so here is what I've talking about:
> http://buyjpi.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=5050T&Category_Code=
>
On Lycoming and Continental the holes are already there. You need to
purchase for that manufacturer.
More info on what engine you are trying to install these on would be
helpful.

Michelle P (A&P)

[flybynightkarmarepair]

Thanks to CW for a useful answer.

Yes, LyCon jugs have these holes, but I'm working on a VW conversion.

After due deliberation, I think I'm going to go the way you went -
spark plug gasket sender under one of the head stud washers, hopefully
the closest to the exhaust port. The CHT sensor boss on the late model
heads is actually measuring the temperature at the rocker box rim,
which is hardly the hottest place on the head. Fine if you're using
it for mixture control, but I'm using it as a warning, so that
location, while it is less prone to mechanical damage than the usual
sensor-under-the plug deal, iis not so great for accurate indication
prior to head melt-down.

On May 12, 6:23 pm, CW Crane > wrote:
> "Kyle Boatright" > wrote:
> >On Lycoming cylinders, I believe the CHT boss is already drilled and tapped.
> >I know they were on mine.
>
> >KB
>
> There is a pipe like fitting that is screwed into those holes. The CHT probe is
> then inserted into the fitting and a BNC like cap compresses a spring that holds
> the tip against the head (at least it was that way with the Grand Rapids EIS
> that I used). The hole in the cylinder head is not very deep at all. Maybe 3/8
> inch. It is really like one of those digital thermometers that you push against
> your head inside your ear.
>
> In another application I couldn't use the 14mm spark plug probe since I had 10mm
> spark plugs and instead just put it under one of the head nuts on my VW.
>
> CW
>
>
>
> >"flybynightkarmarepair" > wrote in message
> ups.com...
> >> How deep is the hole a "bayonet" type CHT probe fits into?
>
> >> I don't like the spark plug senders, and want to drill the cast-in
> >> boss for a CHT sender to suit the probes commonly available, but
> >> without a probe in hand, I can't tell whether this is possible.
>
> >> Anybody who can answer this question already knows what they look
> >> like, but this forum serves an educational purpose for people other
> >> than me, hopefully, so here is what I've talking about:
>