Installing CHT sensor in non-FI head???

[John Fader]

Please consider this a semi-hypothetical, but possibly real, question :-)

Assume for a minute that you want to install an engine from a bus or a T3 VW into a D-Jetronics 914. The head does not have the tapped drilling for a cylinder head temperature sensor. How big of a job is it, or is it even possible, to drill and tap the head for the CHT sensor? I have a milling machine available to do the job and am an experienced machinist.

Any ideas?

Cheers/The Fader

[Ron Meier]

In order to get the contact the factory wants, I would think you would need the engineering drawing from the factory on the heads you want to modify to determine if it were feasible (thickness in the location you want to place the sensor).

You could take a chance and dimension everything off a normal head. You might junk one trying to find out.

1.7/1.8L heads that have the sensor tapped are generally inexpensive (and there are plently of them). It's the 2.0L heads that seem to command much dinero.

[JP Noonan]

I'd look first, I've found that the driver side head and non-FI heads have the CHT "boss" cast into them. All you need to do is drill a hole and tap it.

[Dave at Pelican Parts]

John managed to ask this question on every 914 e-mail list and BBS that I've seen so far...

Anyway, if you're going to use it for a stock-type FI signal, drill the hole, spot-face it, and tap it. No problems for someone who is an experienced machinist, as you have indicated you are (on one of the other lists).

If you're trying to install a head temp gauge, then the FI sender won't work. It is incompatible with the head temp gauge as it works on a different principle. In that case, just use the ring thermocouple that VDO sells with their gauge. You may very well need to notch the recess where the plug goes so that the edge does not cut into the area of the thermocouple that the wires crimp onto.

--DD