Opinions on hot and thirsty 68 ?

[Greg D.]

Apologies in advance if I'm rambling: A while back I convinced a 356 friend to purchase a 911.. he ended up with a 68, sadly I wasn't here to help out check the car. Not an L, just base... All I remember is seing in the books that the engine was the least powerful ever made and teasing him about his 110hp car not being much more powerful than my souped up 912 ;-)



He's had nothing but trouble with the car and now I feel bad: Suspension pan was cut out and redone, one ill fitting window frame preventing glass from rolling up (we found out the door was replaced), some rust here and there - all fixed and no expenses spared, but the car will still not run 100% as we expect. I have a freshly rebuilt 72T, and while our engines are different (2.4 MFI vs 2.0 carbs) his car runs basically almost one entire temps gauge mark hotter than mine in *all* conditions. And he makes at most 12 mpg. Not that he minds, but for a 2.0 that doesn't make that much power, it's underwhelming.

The car was checked by 2 different mechanics of decent reputation who found nothing obvious. The gauge and sender were tested / replaced. The temps are accurate, it just runs about 20F hotter than any other aircooled 911 I've ever seen. 1/2 way on the gauge under normal conditions. It pulls well, feels strong, there are no rags, not obstructions, the oil cooler is clean, no misses, but it's hot. One shop replaced the jets with bigger ones and we suspect they simply tried to make it run cooler by making it richer - hence the appalling mileage. It worked, in that it used to run much hotter, 2/3 up the gauge in normal driving. Now it's 1/2. Where my car barely cracks 1/3.

We checked timing, valves, etc... I'm out of ideas. I think the rich running is a band aid... Ideas ? After the $$$ he put in it, he's getting tired of it and I fear he'll just sell it on...

[Norm01]

Is he running a thicker oil than you?

[Greg D.]

Is he running a thicker oil than you?

I did not think of that... I'll ask. I always ran 20W50 myself, on both 911/912. Though lately I've experimented with 10/40 on the 912 and saw slightly lower temps... Good thought ! Then again he's running hot, so lowereing 50->40 may not be the best ?

[preS]

If you rebuilt your engine w/ a later oil pump and piston squirters that could be part of the difference.

Richard

[Greg D.]

If you rebuilt your engine w/ a later oil pump and piston squirters that could be part of the difference.

Richard

Let's not focus on my engine too much. Mine as far as I can tell behaves normally vs. a bunch of other aircooled 911s I owned or drove. Really, it's his that runs actually 30F too high overall... But it's not going as high as it used to with the extra fuel and some tuning, so maybe it's more normal on earlier cars ? I don't know, never had a 68 911. (for kicks I also got 2x 912s, I do all the work on them yet one runs 20F higher than the other as well, no idea why ;-)

Last drive we took was 20m around town, nothing special. I was running 190F he was 220 easy. Then a sustained freeway on a hot day got me to 210 and him over 230... I just find it odd, but it's not pegged either, so maybe we'll try another oil and see...

[EA911]

A thought: Do the 68 have the 11 blade fan or the 5 blade fan?

[gled49]

have you checked the engine thermostat?

[gsjohnson]

MY 1968 Normal had 130 hp. The described engine temperature is what my 68 Normal runs at. Even after performing the cooling modification of the cylinder tins.

[Fritz A. Ficke]

The single biggest difference in cooling between a 68 and your car is the 68 shroud does not have the separate air duct for the oil cooler. The five blade fan was started in 74 to make the engine run hotter for emission reason, so would not be on the 68 unless some one found one in the garbage and replaced the good 68 fan with it.

[Fritz A. Ficke]

Changing the air shroud and the duct on the back of the alternator will make a huge difference.