Peejay I think you nailed it and that makes sense. My jetting and float level 'before vacuum advance' I had set pretty well. 13's to 14's at cruise and 13's to 12's at WOT.

So far my only test drive with the advance has been around the city so low speed cruising.

I think before I drive it again I will drop the float level by 1mm and see what that does. I do not think I need to drop down a whole idle jet size. And who knows,maybe a bit rich with the advance is ok. If I didn't have the wideband AFR I probably would not even be thinking about it.

I did pull and change the plugs after the test drive I described earlier and they looked good...

Sirv, my jet size refers to the Dellorto idle jets. It sounds like you're running a Holley so don't refer to my jetting!

 

And Holleys don't have idle jets per se, they have idle feed restrictor orifices in the metering blocks, that you adjust with very small drill bits. Going smaller usually means getting another metering block. But they do the same thing, they control the fuel mixture up to the point that the main metering comes online. Those and the air bleeds... which are also fixed orifices that you adjust with a drill bit...

 

@tommyeflight89 Thanks for pointing me to this thread. The nipples you placed in the air bypass do work as ported vacuum for other applications of the DHLA but it depends on what the idle tuning is like. For a ported motor like yours you may see vacuum values above zero because you have to feed enough air and fuel to get a decent idle due to the porting. In fact the vacuum will always be above zero just because they are above the butterflys and even at idle some air is coming through. I looked into this and thats why I asked in the other thread what you had going on. My dell is currently reinstalled on my stock port 12A. In the past I ran it with manifold vacuum and it definitely made it snappier on take off. On the downside it made the idle very lumpy because it was at full advance. I think I'll order some of those nipples and install to see what happens. I'll report back to this thread when I do.

 

I run full manifold vacuum to the dizzy pods on my stock Nikki carb(first port on the spacer). Idles and drives great 👍🏻 no lumpy idle.