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914World.com _ 914World Garage _ Mainley Dipstick Thermometer Installed

Posted by: NJ914Guy Jun 15 2011, 10:40 PM

At the advice of many on the board I installed a Mainley dipstick thermometer, in order to get an accurare read on my oil temps and align them against my factory VDO 1973 (large red zone) temp gauge.

The car is a 1973 2.0 with dual Weber 40 IDF carbs, aircooled.net 034 SVDA distributor w/Pertronix, recently tuned and oil changed (20w-50), and valves adjusted to proper specs. All tins and gromets are in place. The cooling flaps are installed and seem to be stuck in the open position 100% of the time. I assume this as the car usually warms up slow, and the flap arm is rotated up, toward the driver's compartment. The thermo wire is always very tight (hot/cold), with no real play, I don't think it's working.

So, took the car out tonight (after dark) for a good long run. The air temp was 78 degrees here in New Jersey and we drove for a constant 30 minutes on the highway @ 70-80mph, with a couple of short blasts to 90mph. Car was in 5th gear most of the time and the RPM's were constantly over 3,250 at highway speeds. I drove the first 15 minutes and then pulled over to check the dipstick temp. It was reading 211 degrees. Made a turn around, ran another 15-20 minutes (same style of driving) and max temp reading was 218 degrees. After exiting the highway and slowing down on some back country roads, the next dipstick reading was down to 205 degrees within 5 minutes of 30-50mph driving. A few minutes later, we settled in right below 200 degrees on the way home on some roads very close to my home.

Comparing to my VDO gauge, when I had the reading of 218 degrees, my temp gauge was reading about 50%, maybe 2-3 needle widths away from the start of the red zone. When the car cooled down to 200 degrees, the gauge was reading about 2/5 of the way, a couple of ticks further back to the left. My guess is that the start of my red zone is about 230 degrees, and if/when the needle gets into the red, I need to slow down and take it easy for a while. FYI - I have yet to see the needle enter the red zone but have been close a couple of times during hot mid-day runs on the highway. Backroad driving always seems to run nice and cool. Maybe I'm crazy but the car seems to run a bit hotter with the roof off. Perhaps it's the added air-drag (or) could there be a lack of cooling with the roof panel stowed behind the engine?

My question is this - do you think a 30 minute high-speed highway run with an outside air temp of 78 degrees is long enough for the 914's aircooled flat-4 to reach normal operating temp?

Thanks guys, feedback and comments appreciated.

-Chuck

Posted by: ConeDodger Jun 15 2011, 11:10 PM

Oil temperature is not cylinder head temperature, cylinder head temperature is more important...
I don't care what the ambient temperature is, sustained 5th gear driving will get you cylinder head temps over 300 and the oil temperature will rise accordingly if the oil is doing its job. These cars like their fan speed.

Posted by: 76-914 Jun 15 2011, 11:40 PM

and throw in mixture (air/fuel ratio)

Posted by: NJ914Guy Jun 16 2011, 12:56 PM

I know this is comparing apples and oranges, but my 2011 BMW 335i turbo was running an oil temp of 252 degrees today on the highway, 75 degrees outside. It's an inline liquid cooled 6 turbo without an oil cooler but runs synthetic oil. I guess I have a knack for warm oil temps.

Posted by: bembry Jun 16 2011, 06:39 PM

Where do you get the dipstick thermometer? I went driving yesterday, with about the same pattern of driving, outside temp (I was in RI and Connecticut), etc. My temp started coming up on the road when doing about 75 in 5th. I was hoping it wasn't going to go into the red, and it didn't by a decent margin, but it certainly got my attention.

Posted by: NJ914Guy Jun 16 2011, 08:58 PM

Www.mainleycustombydesign.com.

Posted by: BarberDave Jun 17 2011, 07:05 AM

This is exactly why i removed the clock, ( have one on my wrist all the time )

and a VDO oil temp gauge in the console.You don't have to stop and get out to

know your exact oil temp. Yes more expencive than a dip stick gauge but

knowing correct oil temp while is worth the expence. Just my 2 cents.

Dave

Posted by: majkos Jun 17 2011, 07:29 AM

My 2 cents

Left to Right
Exhaust temp,(not hooked up)
Oil Temp.
Oil Pressure
Engine Temp