2 bbl. Motorcraft & a dwell cam

goinbroke2 · 11-13-2013, 07:39 PM

[QUOTE=Dave Noll;408572]The lowest the idle will go down to is about 1600 which isn't the issue. To get that idle with that cam I have the idle plate screw down about as far as it will go. which has the transition slots completely uncovered & I have a 1/4" hole drilled in each throttle plate. With so much air going thru there @ idle it's pulling fuel out of the boosters. I closed the needle valves, lowered the float level, & drilled out the fuel inlet (seat) to .125. The idle is cleaner now but the plugs are still dark.QUOTE]

So, you have the idle screw turned in so far your bypassing the idle circuit and keeping it running by the fuel dribbling out of the booster. (poorly atomised fuel) To clean that up you lowered the fuel level and closed off the needles.
What happens if you lower the rpm, it starts stumbling/bucking because it's rich?

I would say open up the air bleeds to lean the idle mixture, right now if you open the mixture screws at all it sounds like unatomised fuel is dumping in causing the issues. Once it will idle down enough to cover the t-slots it will be more responsive to the screws.

Overall I think lack of vacuum is your main problem and opening the air bleeds will be a good band-aid. (also try reducing the idle feed restriction size if that doesn't do enough)

Oh, if you lock the dist at 40*, use a seperate toggle switches for ign/starter. Get it rolling over then flip the ign on, otherwise it will kick and break the starter nose off....don't ask, lol

11-13-2013, 07:39 PM	#8
goinbroke2 Senior Member Join Date: Mar 2002 Location: NS CANADA Posts: 892 Likes: 1,624 Liked 393 Times in 153 Posts	Re: 2 bbl. Motorcraft & a dwell cam [QUOTE=Dave Noll;408572]The lowest the idle will go down to is about 1600 which isn't the issue. To get that idle with that cam I have the idle plate screw down about as far as it will go. which has the transition slots completely uncovered & I have a 1/4" hole drilled in each throttle plate. With so much air going thru there @ idle it's pulling fuel out of the boosters. I closed the needle valves, lowered the float level, & drilled out the fuel inlet (seat) to .125. The idle is cleaner now but the plugs are still dark.QUOTE] So, you have the idle screw turned in so far your bypassing the idle circuit and keeping it running by the fuel dribbling out of the booster. (poorly atomised fuel) To clean that up you lowered the fuel level and closed off the needles. What happens if you lower the rpm, it starts stumbling/bucking because it's rich? I would say open up the air bleeds to lean the idle mixture, right now if you open the mixture screws at all it sounds like unatomised fuel is dumping in causing the issues. Once it will idle down enough to cover the t-slots it will be more responsive to the screws. Overall I think lack of vacuum is your main problem and opening the air bleeds will be a good band-aid. (also try reducing the idle feed restriction size if that doesn't do enough) Oh, if you lock the dist at 40*, use a seperate toggle switches for ign/starter. Get it rolling over then flip the ign on, otherwise it will kick and break the starter nose off....don't ask, lol