Engine is rebuilt and back in the car. Set the timing and adjusted the carburetors and it’s idling at 700 rpm and sounds pretty good with no Missing. However when it’s idling it seems every few seconds to have a very slight surge in the RPm’s. It’s very slight you can barely see it on the tachometer but can definitely hear it. Otherwise the engine seems to be running quite smoothly. I thought maybe it was a vacuum leak but I am unable to find any so was hoping for some suggestions
What ignition system are you using and have you listened to the exhaust pipes? Is the exhaust an even beat for does it have a periodic miss?
Have pertronix ignition. The exhaust is pretty even with no missing
When mine has been too rich it seems to surge. What it really is doing though is bogging down and then suddenly recovering. It does this cyclically.
Mine was doing the same (brief stumble and recovery). I finally pulled all the plugs and discovered that the plugs for the two cylinders supplied by the center carb were black and sooty. One full turn on the mixture screw solved it.
Thanks, I’ll give it a try
Classic rich mixture lope.
Or you included a cam shaft with a bit of extra duration and over lap… Idle smoothness never concerned me a heck of a lot, just don’t stall…
My critters idle at a relatively smooth 500 rpm…when warm. cold at about 700 !
Carl