cylinder head temp gauge, spark plug washer type Options

[Elliot_Cannon]

I have a 1973 with a 2.2 4 cylinder. I'm a bit paranoid about temps and would like to install a cylinder head temp gauge. If I use the spark plug washer type sender, which would be the best cylinder to install in on? Which would be the hottest?
Cheers, Elliot

[ChrisReale]

Typically it goes on #3

[SirAndy]

in a type4 they should all get equally hot (in theory at least),
#3 was hotter on type1 motors because of the different oil-cooler placement.

anyways, i'd say it's pretty useless unless you install one for each cylinder.
there are switches you can install in front of your gauge that let's you switch
between the 4 senders, or, you can get 4 gauges ...

the spark-plug senders work fine, but remember that that also means your spark plug will not be all the way inside the head and most likley not in the same rotational angle as without the sender, which might cause some loss of spark ...

EDIT:
loss of spark not as in electrical, but rather blown out by the moving gases etc.
or the spark ends up in a location not ideal for igniting the fuel blah blah ...

Andy

[john rogers]

We have one in my race car and found the following interesting things with it: Temps came up fast when starting the engine but stayed pretty constant when racing. Temps were about 325 degrees at full power and then we figured total advance was a little too low and we were not getting good combustion. Added 4 degrees more advance, head temps went to 375 degrees, power went up slightly (dyno) and exhaust temps went down 250 degrees which was good for the exhaust valves. The engine runs 100 octane Union 76 race gas so we were not getting good combustion it seems. I also have a a/f meter and noted that if I coast a little such as the entry to turn 9 at Willow Springs that a/f mixture drops off quickly and temps go up 25 degrees or so then come bach by the middle of the front straight.

[makinson1]

Wasn't there some sort of sending unit already in one of the heads that went to the computer for the fuel injection? If so, can't it be hooked up to an Autometer Cyl head temp gauge?

[tat2dphreak]

the stock location was for the FI and not as accurate for overheating... read this:

ShopTalk Forum type 4um posting

jake has found that the stock location reads as much as 100 degrees cooler than under the plug.

this thread has tons of good info about CHT

[makinson1]

100d cooler? I'm only looking for relative indication, after all, it's not the Space Shuttle.

[tat2dphreak]

the stat that really caught me is how it took so much longer to get warmed up.

but it IS just a baseline.

[mr914]

Dose anybody know if the VDO head temp guage sender is a type J or type K thermocouple?

I broke mine last year...

Now if you want to monitor all temps. They do make a rotary switch for thermocouples.

[tat2dphreak]

I was talking to a wise vw guy the other day and he let me in on his tips for the CHT gauges... he would in stll one on a cylinder and run it for a wekk or so pretty hard use... get a feel for how that cylinder acts... move to the next cylinder... repeat... etc... once he got a feel for how each cylinder reacted, and what a good base line was, he would spot weld the senderin beween the cylinders on the hotter head...(typically the 3,4 side for all of his bus' and 411s he'd had) the baseline number would drop some in between the cylinders, but he said keeping it underneath a plug was just too much hassle since he would pull the plugs in his engine often. even though the temps ran cooler than under the cylinder... he could look at the gauge and be able to ballpark where any given cylinder should be... and a spike in temps would still indicate: watch out!

he did say it was essential to check the temps on all cylinders... he had seen a VW or 2 that ran hot on the opposite side of the engine for some reason... (possibly the re-builder used poorly matched parts or that side was running a weaker fuel/air mixture)

it was an interesting conversation, I thought I'd share...