cylinder head temp

[Dale L Jensen]

got my project on the road last night (I will post pictures soon)
so i will be asking questions to get it tuned and going perfect
first lets start with cylinder head temp what is the range I have a gage and just tooling around the block and geting things going it would get up to 220 befor i would shut it down oil temp gage not yet working yet one of the things I have to work out oil temp is still a question
any help thanks Dale

[bob174]

I put in one of the new VDO oil temp gauges recently and although the new gauge has the same spade terminal arrangement as the old gauge, two of the wires in the connector harness had to be switched around in order to make the old connector work on the new gauge. After looking at the wire designations on the old gauge and comparing to the new, you'll see the difference and can make the change in the connector from the car. If I recollect correcly, I think it was the "+" and the "S" wires that needed to be swapped. As a side note, it takes a while for the oil temp to come up in my car (I don't think the thermostat is working correctly). It was 40 degrees this morning, and it took about 10 minutes for the oil temp to come up to 120, about 20 minutes to hit 180. The car's normal operating oil temperature is between 180 and 200. I've read on this board that the cylinder head temp gauge reacts very quickly to temperature changes, and it's obviously going to run quite a bit higher than oil temperature--I believe that I've read on this board that they hover around the 325 range (correct me if I'm wrong, guys).

[pbanders]

I don't know if you're running carbs or FI, but if it's FI, the ECU uses head temperature to signal when to turn off the warm-up enrichment. If you look at the graph in this section on my ECU web page:

http://members.rennlist.com/pbanders/ecu.htm#CTC

...you'll see that from the ECU's perspective, the engine is fully warmed-up once head temp exceeds 210 deg. F. I've noted that on fully-warmed up engines that the CHT reads about 50 ohms, which would be somewhere in the 300 deg. F range.

Note also that head temp is highly dependent on the location of the sensor. The VDO head temp gauges usually have a sensor that goes under the spark plug, whereas the CHT used with D-Jet is located away from this area - I'd expect a significant offset.

[jamcleod]

i've seen numbers like 325-375 degrees for head temp. i put a head temp gauge in an 81 Vanagon (mostly for kicks), and i remember reading the desired range is 325ish. seem to relate this info to a site for "boston bob" a type IV/vw van guy. 375 was supposed to be on the hot side.

[Dale L Jensen]

Ok I left out some inprotiant info webbers, autometer gages,cylinder head temp sending unit screwed into the spot in the head BY (not in) the #3 plug and 9.1to1 compression