Rough running, rough idle

[Tezza]

My 73, 1700 was going well till a few weeks ago when more or less suddenly the idle became rough & seems to run on about 85% power rather than 100% when going.....and it's not running as smooth as it used to at speed. At the same time I can hear occasionally a "pffft" sound from the engine, like a backfire but not coming from the exhaust.
First thought was to check the plugs...looked ok, but put new ones in anyway.Didn't help.
Checked all leads etc....all ok.....haven't done timing or tappetts yet as I thought they shouldn't change suddenly.
The only thing I found amiss after staring & poking everywhere was the cylindrical electromagnetic valve device on the left carbie ( from the rear....RHD )....this carbie seems to have two, one larger than the other...the larger one which is highest & closest to the firewall is the one that was loose.
Pulled it out & tested it on 12V...works but you have to give it a little push ( I think I recall reading somewhere that this is normal ).
Put it back in tight & tried again. Somewhat better with fewer "pffft"s but still not right.
Apart from checking timing & tappetts any ideas???
Spose I will have to check compressions to see if a ( intake ? )valve has gone?
Puzzled & starting to get the "what's gone wrong now" VW blues!

[[email protected]]

hey my new to vw so i don't know how much elp i caould be. but i have close to the same problem u have with me 74. i think a compressions check would be good.. if u got carbs mayb a adjustment might be needed? i hope i helped
smllthrck

[[email protected]]

That "ppppfffttt" sounds suspiciously like a valve ,although it might be an exhaust leak. First things first, compression check all the cylinders. If ok and 20% of each other try unplugging one wire at a time a note if the noise goes away. Let us know how it works out.

[jmattp]

yo same thing happened to my bus. My muffler is completely disconnected from the heat boxes, so I assumed it was the valves. Still waiting on that though, so I can't tell you if it is or not.

[nodtobob]

Have you syncroed your carbs and dialed them in together? I agree with aerculd on unplugging the wires and see if all cylinders are firing correctly and check the condition of the spark plugs on the side of that carb it will tell you alot on how that carb is running on that side. anthony

[Tezza]

Thanks guys, will do the above on the week-end & report back
Terry

[68Mccabe]

My distrubitor clamp stripped out and threw the timing out the window. Be sure to check there as well.