I installed a CHT sensor/gauge over the winter in my ’75 1.8 with L-jet. Since then, I’ve noticed it runs hot. Examples: around town in 3rd and 4th gear it’ll run right around 350. On the highway in 5th at 3200, it’ll be a 375 and I can get it to 400 by stepping on the gas a little more. The oil temps are normal. The car seems to run fine. It accelerates to 5000 easily. It idles fine. No stumbles at any rpm range. No smoke.

Here’s what I’ve checked: the dwell, idle and timing are all within spec. I’ve used an infrared thermometer to check the accuracy of the gauge and it is accurate, once you compensate for the ambient temp. #1 and #2 cylinders were about 15-20 degrees cooler. The gauge is a VDO (I know, not the best). I’ve disconnected the thermostat cable so the flaps inside the fan housing are at full cooling mode. The coil, points, condenser are new. The plugs are almost new. I removed the engine tin over the winter and cleaned all the fins on the heads and cylinders. All the engine tin is in place. Valves were adjusted about 700 miles ago. Gas tank is newly refurbished. New fuel lines and filter. Injectors were cleaned, tested and screens replaced 700 miles ago. I’m getting 23-25 mpg.

I’m running out of ideas. I’m thinking of re-checking the valve adjustment, however I don’t hear any objectionable noises.

Chris,

I think the '75 and '76 were designed to run hot. I have never heard that much detailed information from a stock motor but I suspect it to be normal. Ask that same question on Aircooled Technology Forum in the 914 section... If not, you will get more information there than here. Jake will answer it.

What did you use for your ignition timing spec?

I believe that stock spec for that car is 7.5deg BTDC and when I set my 1.8l L-jet at that spec, it also seems to run rather hot at that timing. More advance leads to pinging due to my increased CR from stock.

I've heard people state that a 1.8l l-jet needs more advance to run well, but I've never seen a spec.

Do let me know what you find out as I have the same issue, or so I think I do.

It is a good sign that your oil temp never gets to an elevated level, but you gotta keep those heads cool.

Good luck!

wow, mine's the exact same way except I have dual webers.

Dunno what to tell you man. I'm selling mine

How accurate is your gauge? Your temps might be normal. How hot is the oil?

The gauge is accurate (see original post). Using an infrared thermometer with a laser guide, I found the highest temps either right on the plug or right where the plug meets the head closest to the center of the motor. If I moved the laser just a few millimeters away, the temps dropped quite a bit.

The oil temp seems fine, according to the oil temp gauge. I would assume the oil temps can be normal and the head temps too hot.

You're having the same problem I'm having.......Seeing as how Jake isn't responding here, from what I've read, the stock cam timing was designed to warm the car up quickly during those cold German winters. Jake has redesigned the cam for better performance and cooler running heads by opening the exhaust valve earlier. My 1911 with webers runs almost exactly as you describe. Two solutions: 1) disconnect the head temp sensor and drive it. 2) Rebuild it with new cam from Jake

Don't automatically assume that a new cam from Jake will fix the problem. You can find lots of other issues that cause high temps.

I replied over on my forums and then the server died and I lost the post!! I'll re-do it in the morning..

The issue is using 5th gear too early! And more than likely the engine doesn't have the tuning it LIKES, that tuning is usually only found after making numerous changes and logging the temp differences. Stock specs suck!

Check your spark plugs too! It's an easy way to see if you're running lean.

YMMV, but the biggest change to CHT for me was adjusting my timing. I know you said that you just did a tune up, but it's something you may want to double check. You also said it runs fine up to 5,000k RPM, but how does it do at redline? I'm not saying that you should take it up and there and leave it, but it shouldn't stutter or do strange things up in that range. I ask, because if things are out of wack, redline can sometimes be unobtainable.

Well, I've been playing with the spring inside the AFM to try and richen the fuel mixure. The flapper is attached to a wound spring. The spring is attached to a plastic gear, which is locked in position. I marked the original location before moving the gear. I turned it CC-wise 5 clicks, then 3 more, and now recently 3 more clicks. It has made a noticable difference in the temps in 4th and especially 5th gear.

I can now drive in 5th at 3200 rpms and on a flat road, the temps stay around 360-70. Much improved. I'll check the gas mileage on the next fillup.

If you need to borrow a good AFM...we happen to have one that is in the purple car...recently bashed in.

I will want it back eventually, but no hurry.
That car ran perfectly.

Rich

Thanks for the offer. I'm going to run a tank of gas thru the car and check the plugs and mpg. If I don't like what I see, I may take you up on that offer. I'm just happy I can cruise at 70-75 mph.

That is a correct assumption, these two sometimes don't corralate.

Did you recheck the timing? How many miles on the engine? Is it clean? what weight oil? These are all a factor.