Running hot

My CMC kit has a 1972 motor, with the 88mm pistons, a mid-range cam and twin Webers. I also put in the auxialiary 1 quart sump. Around town it generally runs 160-180 degrees, but at anything above 60 mph it gets quite hot- over 200 degrees, or at least the gauge says so. Since it is a Vingage brand guage, I'm somewhat skeptical, since the speedometer is accurate to within 30 mph or so, but I don't want to take any chances. I realize that this could be due to a multitude of factors, but does anyone have any thoughts as to the most likely culprit?
Many thanks.

Have you read the writeup in the "Knowledge" section on cooling?

Also, check to make sure your engine has all of its cooling sheet metal and also be sure the engine compartment is sealed around the engine itself. Can you see the ground around your engine?

When I bought my used McSpeedster it was missing the engine compartment sheet metal which caused it to run hot.

If you want to know how hot your engine is, try sticking a cooking thermometer, or something similar, down the dip stick hole after a good run.

I don't think you have to worry about 200 - 210 degree oil temps. When it goes to 250 and climbing is when you need to change things.
160 - 180 degrees is great, but I don't think a VW aircooled based engine will keep the oil that cool at prolonged turnpike or freeway speeds.
Have any of you got a set up that will keep your oil that cool, say at 80 degrees ambient temp. running 55 - 65 mph, for several hours?

Greg B.

(Message Edited 9/20/2002 10:20:10 PM)

slipping belt?

I agree that in the summer, pushing it on the freeway, the Speedster is going to run hotter. 220 would not be unusual. 250 would mean stop for 15 minutes, then slow down. With that set up you should be able to run down the road at 70 MPH and stay in the saftey zone around 220. If not, check the cooling file. Especially about running lean, or not having the compartment sealed.

Hi

Thanx for your insight on engine temps you guys read. I take from your posts that 220 degrees is OK on fast rides. I get about 230 when I go 100mph+ for a couple of minutes (live in Europe).

What is your opinion on extended high speed driving above 100mph(OK for engine; 2100 cc CB performance)? Is that a problem ?

Ed.

Ed, Porsche 911 oil temp gauges originally had numbers on them, and since they consistently ran hot oil at speed that worried owners, Porsche changed the gauges to have the "green band" operating range. In the 1960's Corvairs used to run high oil temps on the highway with no problems as long as they had regular oil changes.

I would think that with modern oils (which have come a LONG way in development) 240 F is probably OK but approaching marginal with normal oil and 260 F is probably OK with synthetics as long as reasonable oil pressure is maintained.

I would be more concerned about cylinder head temperatures at a sustained 100 mph cruising speed.

I dropped my oil temps in more than one test engine by 30-40 degrees just by switching to Synthetic oils...Not all of them do this, But I know of 3 that I have proven.

Ambient air temps have more of an impact on oil temps than head temps..

In my testing I have found that head temps and oil temps are not dependant on each other at all. I have also found that correct gearing plays a key role in oil temperatures, the higher the revs the more friction and the hotter the oil temps get....

I use synthetic oil and will take Georges advice of 250 to 260 as a max.

I will also check the oven gauge I use (dipstick oil) with boling water as I do not trust this device. The remark on the green band in the regular gauge is good: my reading is allways in the green (lower to middle part) and has never moved to anywhere close to the red. ut reading on the dipstick can stillbe 240 degrees. I will check and post back.

Ed