Guys, I need some advise, I have a 1966 912 engine with Pertronix 91874A ignition, and fairly new weber carbs, I have a flutter at around 2000 rpms, I am not sure of the settings for timing, are are not sure where the problem lays. Compression is good, are there any suggestions.
thanks
Replies sorted oldest to newest
I'm not familiar with the Pertronix unit- is it a drop in electronic module or complete replacement distributor?
Did it run well on the Webers then change or is the flutter new with the Webers? I ask because depending on the type and size of Webers you are running 2000 rpm is about the transition from idle jet to main jet. This can mean the idle jets are a little too small or the mains a little too large. If increasing the accelerator shot size improves or gets rid of the flutter the cause was in the jetting. The same can be caused by clogged idle jets making a lean condition as well. A flutter at a certain RPM is most certainly a carb issue.
Al, are you serious? The Pertronix drop-in points replacement module has been a well-known thing since the 1980s. I have installed a few, most recently in my FV.
95% of carb problems are ignition. But if the car has sat, it probably has a plugged jet or two. Are you experienced with multi-throat carbs? If not, the learning can be difficult for some guys.
In my experience, the transition from idles to mains can encompass 1500 to 3500 rpm, depending on the individual engine.
I'm not familiar with the idle or full advance timing needs of a 912 engine, but idle advance is irrelevant(1874A Pertronix is for 009). Only set an 009 at 3000 to 3500 rpm to nail full advance. Unless you have a vacuum-can equipped distributor. In that case, refer to the specs for your engine.
