Cooling RPM, Oil temp Vs RPM Options

[DavidSweden]

I have got my engine back together and running after 2 dropped valve seats.
I am keen to keep the heads cool, I think I read something on this forum about keeping the engine revs about 3500 to provide adequate cooling even if this means driving in 4th gear to keep the revs up.

What to members advise?

[Big Len]

Is the motor stock is probably the first question?

[DavidSweden]

Is the motor stock is probably the first question?

Yes stock 2.0

[porschetub]

Is the motor stock is probably the first question?

Yes stock 2.0

Correct assembly of the motors cooling tins(no gaps),clean oil cooler,good engine compartment seals and plug seals,a clean motor,a good tune-up (using the right plugs),timing ,rocker clearance etc etc,all add if to make an engine run cool enough.
No air-cooled engine likes to be "lugged" so this method would have its merits if you suspect overheating or are driving with the oil temp gauge,how hot is the summer in Sweden ??,cheers.

[Elliot Cannon]

On the way home from a route 66 tour, I found myself climbing a very long fairly steep hill out side of Needles California. I noticed the car not answering throttle like it should. I looked at the CHT and it was WELL over 400 degrees. I thought I had cooked it. I pulled over and stopped, shut the engine down and let it cool off for about 30 minutes. When I got out of the car, it was VERY difficult just to get the door open and it was then I realized not only was I going up a long steep hill but I was going into about a 30 to 40 mile and hour wind. (IMG:style_emoticons/default/w00t.gif) I took the advice I learned from Mr. Joe Sharp (a long time and well respected air cooled engine guy) and drove all the way to Barstow in fourth gear and about 65 MPH. By keeping the rpm's up and the resulting increase in cooling fan speed my head temps. went back down and stayed at 325/350 which is normal for my engine. Oil temp. stayed at 190. So, I'd say, "yes keeping rpm's up will help keep the CHT's down". (IMG:style_emoticons/default/laugh.gif)

[Elliot Cannon]

Is the motor stock is probably the first question?

Yes stock 2.0

Correct assembly of the motors cooling tins(no gaps),clean oil cooler,good engine compartment seals and plug seals,a clean motor,a good tune-up (using the right plugs),timing ,rocker clearance etc etc,all add if to make an engine run cool enough.
No air-cooled engine likes to be "lugged" so this method would have its merits if you suspect overheating or are driving with the oil temp gauge,how hot is the summer in Sweden ??,cheers.

(IMG:style_emoticons/default/agree.gif) Another thing you can do is push the spark plugs seals inside the cooling tin. When the cooling fan pressurizes the cooling shroud/tin, it will seal better.

[Big Len]

Elliot - I know far less than you, but I had this conversation with Porschef last week, so let me ask you -

If the car is set up stock...Air/fuel mixture, timing, fan and belt in good shape, no deep air dams, using the correct grade oil, correct temp. plugs, etc, etc. Shouldn't the car be able to handle that kind of load? Wouldn't the factory have tested the cooling system under extreme conditions when the car was developed? If one factory spec is off, wouldn't that contribute to overheating?

I just don't see a reason to keep high revs unless under the most adverse conditions.
Is that correct?

[dangrouche]

check third message down on what Jake Raby has cited


http://www.914world.com/bbs2/index.php?sho...temp,and,normal

[DBCooper]

Wow, Perso and Lapuwali. What ever happened to Tom? I remember he went on to engineering school, but that was the last.

[era vulgaris]

Elliot - I know far less than you, but I had this conversation with Porschef last week, so let me ask you -

If the car is set up stock...Air/fuel mixture, timing, fan and belt in good shape, no deep air dams, using the correct grade oil, correct temp. plugs, etc, etc. Shouldn't the car be able to handle that kind of load? Wouldn't the factory have tested the cooling system under extreme conditions when the car was developed? If one factory spec is off, wouldn't that contribute to overheating?

I just don't see a reason to keep high revs unless under the most adverse conditions.
Is that correct?

You're thinking like a water-cooled driver. Air-cooled engines are designed to run between 3K and 4K rpm for cruising. They're just different than water-cooled engines. Get used to it. Really, GET USED TO IT!!!!

Also, here's a quote from the late and very great Cap'n:

3500 RPM is cruising speed, NOT where you should be shifting. I recommend 4000-4500 as a shift point, and NEVER load the engine under 2500 RPM. Too many 356s, I guess, where cranks break under low RPM loading. As for 5th gear, I recommend cruising in 4th anytime you're under 60 MPH. Keeps the fan speed up, allows you to jump on the gas when necessary. 5th is an overdrive gear, meant for sustained high speeds on freeways and such.

The Cap'n

[yeahmag]

Interesting. I never feel like those seals "seal" well anyway. Anybody else doing this?

(IMG:style_emoticons/default/agree.gif) Another thing you can do is push the spark plugs seals inside the cooling tin. When the cooling fan pressurizes the cooling shroud/tin, it will seal better.