Hello all,
First of all, I want to preface this by saying I just read the post below from tornik regarding the constant rich condition he mentioned. When I go to pull the carbs apart, I'll definitely check for the hole in the gasket to see if its there.

Anyway, I've got a couple issues and need to bounce this off of your experienced and attentive minds. A couple months ago I got the car running again and have been driving it like crazy! I am commuting an hour and half to and from work and when my water-cooled vehicle started leaking coolant like a sieve, I had no choice. Probably not the best idea, but the 914 got me to and from work each day like a champ (until I had an engine fire, which is a story for another day!)

The good thing about this drive is it gave me a chance to troubleshoot some of the problems I have with the car. First, this an easy one. I adjusted the valves after replacing all the pushrod tube seals and as a first timer, I think I've got some learning to do. At first, I know I had them too loose because I had some real valve noise. I went back to do them a few days ago but think I might still have them wrong - at least I hope. I now have approx 60 PSI compression from all 4 cylinders, but when I first got the car several months ago it was around 120 on each. Is it true if they are too tight that your compression numbers will actually drop? Or is it possible I killed the rings/valves in just a month of driving?

My other issue is that I still cannot get the carbs synched. I finally got the linkage straightened out but it still runs awful. Usually I have problems in 4th and 5th gear transitioning from neutral throttle to about 1/3 way. It hesitates bad and seems like its not running on all 4. Adding throttle helps for a bit but even at full throttle its not quite right. It does idle well though.

I had just about run out of ideas till tonight. I tried the carb spray around all of the gaskets trick and had no results... until I sprayed the throttle shaft bushings. When I sprayed that area the car began to drop RPMS and idle poorly. Is it possible it could be leaking air from the bushings? I seem to remember this is a common problem with some carburetors. These are two Weber 40 IDFs from a 912 that I got on Ebay. I'm sure they have some miles on them, but as far as I can tell there is no play from the throttle shaft bushings/bearings. Still, does this sound like a reasonable cause for the issues I'm having? If so, does anyone know where to purchase replacement bushings/bearings and what part numbers I would need?


As always, thank you tremendously for your help!

Fist , I don't think a leak on the intake or gaskets would drop your compression .

2-Did you do the valve adjustments with the engine cold?

3- what was the engine temp when you tested for compression?

4- have you tried cleaning your jets?

Give us these info's and we will try to help.

Hey Paul,
I didn't mean an intake leak. I meant after adjusting the valves, couldn't my compression numbers go down if they are too tight?

2 - Valve adjustments were done stone cold.

3- The compression was checked both cold and warm and was approximately 60 PSI each time (no change from cold to warm).

4 - Both carbs were rebuilt and dip - cleaned before installing on the engine. I have verified that all 4 idle jets are not clogged either.


After doing some more reading I am fairly certain that the throttle shaft bearings are the culprit for the rough running. They don't look like they have ever been replaced and the seals inside them are probably gone. I'm going to order replacements since they are cheap.

The compression is what I'm most worried about.

Was the compression test done with both trotle fully open?

I am not sure if the tight valves wiill cause a drop in compression. I am sure an expert will shime in soon.

I am no expert (but I'm old) but I know that if your valve adjustment is too tight, they won't close completely. So yes, it could result in low compression, burnt valves, poor running.

Keith

Thanks for the replies guys. I've pulled the carbs in anticipation of getting new bearings in the mail by Friday. Paul - I did not know that the throttles needed to be open for a compression test, but that makes sense! Thanks for the heads up.

With the car awaiting the carbs, I'm going to loosen the valves a bit and see if it makes a difference. Will let you all know what I find.

Thanks for the replies guys. I've pulled the carbs in anticipation of getting new bearings in the mail by Friday. Paul - I did not know that the throttles needed to be open for a compression test, but that makes sense! Thanks for the heads up.

With the car awaiting the carbs, I'm going to loosen the valves a bit and see if it makes a difference. Will let you all know what I find.