wierd surging

this morning i noticed some surging from my 2ltr twin carb bus, it happened at 80 clicks, and then repeatedly over the next few k's, i checked the plugs and leads, all ok, i also noticed a slight knocking sound from the right side of the motor, correct me if im jumping to conclusions but im hoping its not the valve hammering the valve seat into the head,
i just dont want the bus to die on me, any guidance would be greatly appreciated..... im a newbie even though its sounds like i know what im talking about

Thanks guys

On the run up to Valla my 2ltr was doing something a little similar turned out the vaccum line had come off the distributor......after it was put back on she cruised the rest of the way no probs.Not sure if this helps at all but just thought it would be worth checking.😉

yeah checked.... no good all fine,
the bottom end was rebuilt 15000k's ago and the top end was done a year and a half ago, hopefully nothing major

as others will tell you, check valve clearance, timing and fuel mixture in that order before anything else. that said though surging can be a symptom of bad fuel (or fuel blockages) or its just time to change the points AND condensor, or a dodgey coil (usually starts when hot but will be ok when cools down) or on and on.dont start pulling hair out until youve done those things.and as one newbie to another newbie to DIYer, buy a manual or five.HTH

thanks franko,
you are a champ, you hit it right on the head, it only happens when its hot,
putting her in for a major service soon, will try and tackle it when i can get a hold of john muirs book 🙂

Thanks a million guys

just to reboot this post,
bus still running like a dog, i now have an electronic ignition installed, new points plugs leads and vacuum advance, also filter and oil, sounds nice although still surging like a dog, i have had the carbies blown out, they are fine, i tried metho in the fuel tank to hopefully get rid of the water if any..... i think it might be shit fuel........any suggestions guys as i am at a loss now 🙁 as the bus is off the road

just to bumpity bump, by bus is now bucking like a bronco
cant even drive 100m without surging, if its the fuel i cnt drive it out cause it kicks so much it feels like its stressing the gearbox??? i now have no idea