Weber 38/38 running funny, verified no vacuum leaks.

[TheBirdistheWord]

I've got strange off throttle issues while trying to tune the idle circuit screw.  Turning both screws all the way in won't kill the engine, with both screws open the engine doesn't need more than a half turn out to idle right.  This creates slight surges at idle and a consistent off throttle dip that will almost kill the engine in most actual driving conditions, it doesn't do this while warming/warmed up before a drive. So, I tried tuning idle with one screw closed all of the way. 3.5 -1 turns out creates various large prolonged surges off throttle, but it idles alot better overall.

 

I was breaking in some rings while trying to tune this for the first time so I'll be doing a compression check today to cover my bases. I do have some slight smoking out of the tail pipe after 100 miles and an oil change. I'm hoping I can get by with some thicker oil to mitigate this.  Seems like either or both main/idle circuits are to rich/large. Just looking for some feedback and wondering if anyone knows what jets the 38 comes with stock so I can compare. 

[hosestop@msn.com]

Ok grab the throttle shaft and see if has some side play while bolted down , any is too much ! seen worn carb body leak at idle ,years of a strong spring .

[TheBirdistheWord]

There's no throttle shaft play whatsoever. It was a very lightly used good condition carb when I got it.  Compression test came back as:

Cyl 1 156

Cyl 2 120

Cyl 3 158

Cyl 4 151

 

That obviously needs to be addressed before I can assume it's carb related. I had another post a few weeks back detailing a rocker arm that fell off on the number 2 cylinder during high rpms I'm now thinking it's safe to assume the valve seat is damaged preventing proper compression. Looks like the head needs to come off. 😬😣😭