I recently replaced my intake manifolds on my 914. I had a crack in my old manifolds from over-torquing them, Now I noticed that I have a lot of cold condensation on my new intake manifolds after running the engine (I didn't notice this with the old carbs but I dont remember ever checking). It occurs on all cylinders. I have a 2.27l with dual weber idfs. It is idling a little rough but I am working on some jetting issues so I am not sure what is causing that (I assume the jetting issues). I removed one of the carbs about 5 minutes after running th engine and there was a large amount of "fog" in both manifolds. I couldn't smell it from my position so I couldn't tell if it was gas vapor or water vapor. The intake manifolds are very cold. My engine is sucking in a large amount of air. With my "snail" synchronizer, the readings are always towards the top (25) at idle).

Is this normal? Any ideas?

Also, when I changed my intake manifolds, I also changed to 34mm venturis from 32. This is why I am changing my jetting. I assume that the vent increase is the cause of the increased air. Not sure if that is the cause of the condensation.

A drop in pressure results in a drop in temp. Low pressure air cools the manifolds. Think cold beer hot day. I prefer the unisyn. I had the same problem with the "snail." I am by far in the minority for that preference. Most feel the "snail" is more accurate. I don't disagree with them. I just prefer the unisyn for its adjustability and simplicity.

So this is normal for intake manifolds? I have a unisyn somewhere. I will have to dig it out and try it again.

It's normal. You pulled them before the heat from the head transfered. A cold surface will have condensation on it in the humid summer months.

Tell us about the rough idle. Is it rough at idle with the butterflies closed or is it rough just off idle when your opening the thottle?

If you twist the base of the snail it opens a couple of holes and will bring the needle down to a readable level. The numbers are meaningless it's the sync (balance) you're after.

The number 1 dual carb issue is always poor linkage install and/or adjustment, see if you can make it idle better with one arm off.

If you have an old enough UniSyn they're very nice. The 'new' ones I have seen are very crude copies, possibly made from the original 60-year tooling but now in China. Based on what I've seen of those, I wouldn't buy a 'new' one. I'm keeping mine, which I've had for 40+ years, and it works fine, but my personal experience with the 6-cylinder cars is that the Syncrometer works better for me.

And yes - any time you evaporate a large amount of liquid it will 'make cold.'

On the condensation issue, I had a '68 Beetle AutoStick which shut off at the bottom of a highway off ramp on a very hot, humid day. When I opened the engine cover the carb was a ball of ice. An hour later the car started and ran normally.

Wow. I wouldn't have thought it would have gotten that cold. Since things haven't been quite so humid, I haven't noticed the cold condensation so much.