Don Terrill’s Speed-Talk

I need some advice with overly rich idle with twin 45dcoes on a holden 308(A9X style).I started a thread here some months ago regarding set-up which is now pretty close thanks to some good advice but I still have one little problem...weak or rich idle.
If I go lean on the idle jets,say 45/1.20 air or 50/1.50 air,idle is weak and stumbles off idle but if I go richer(bigger fuel or smaller air) stumble's gone but fouled plugs at light cruise and spitting fuel at warm-up.
I don't think its a accelerator pump issue though.
ATM Idle jet is 50 with 150 air hole
50 pump jet
45 spill jet
Throttle blades are in right position and engine has 7hg vac @ 1000rpm with 16-34 degrees timing........Any thoughts???

Have you tried different model number 45s? I'm thinking that the transfer ports aren't appropriate for your setup.

I have thought that,dcoe 13 only 2 progression holes but I dont know enough about them to start drilling holes

Try some 3 port 9s or 152s. 15s+16s are 2 port.

Rocket,
Check your PM box.

Scalloped throttle plates might help too.

Runit wrote:Scalloped throttle plates might help too.

I have drilled 1mm holes in blades to get them to close and cover 1st progression hole at idle(maybe wrong move) cos have only 7hg vac @ idle.Thing is,I go bigger on mains and get good performance with good plug colour racing around but then fouls plugs at cruise....different idle jets have only subtle effects

Suggest you search Yahoo discussion groups for < Sidedraft Central > , hosted by Keith Franck. He's been working up a very technical approach to sorting DCOE issues for years and has developed a number of components for improved behaviour. Lots of techniques also expressed for dealing with the transition gaps inherent in most DCOE applications.
Steve

Yes ,I was reading some of Keith Francks info yesterday and it has answered some of my questions,most stuff I've found just repeats the same old baseline setting thing but not 'how and why'.Looks like I'll be making some big changes with fuel levels and main/ac selection...and hopefully stop chasing my tail.

This morning I remembered working on a Weber that was one of a pair on a sidedraft adapter for a SB Chevy. The customer wanted new low speed jets installed which I had to make. I thought I jotted the calibration down but I can't find the notes. I do I remember seeking guidance from Mike Pierce at Pierce Manifolds if that helps.