After a few years of sitting dormant, I took the Astro Van out for it's maiden voyage. Besides leaking oil like a seive (apparently World S/R heads aren't really ready for center bolt valve covers without machining) the engine ran okay except for idle. I'm getting stalling out right now at times and it's kind of like a light switch off throttle. Combo is as follows:

3.23 gears
383 CI, 9.5:1ish engine
276HR Comp cam (110 LSA, something like 226@.050)
Megasquirt II ECU
World S/R Iron heads
Holley Stealth Ram intake, 55lb/hr injectors
small cap HEI
2400 stall TCI streetfighter in a 700R4 which seems lightly modded

Idle RPM out of gear is 750 and drops down to 500ish in gear. I think this is too low. At what point do you stop adding idle timing and start adding a bypass to let more air in at idle?

 

Why are you running such monstrously huge injectors for this? That alone is going to make dialing in idle fuel difficult.

 

Had em. Would like 36es but that's life. May go E or boost later on.

 

I bought some of those heads, and they didn't work right for either type of valve cover. I ended up grinding the head for clearance and used the center bolt covers.

 

Just an update, figured out a few things. First off my injector dead time was set to about .9, I ended up at about .5. Seems really high for 55s but hey I'm going to roll with it. These injectors (decapped SVO 36es) aren't really well documented I suspect and it gained fairly significantly in idle quality.

The big thing however was my TPSDOT accelerator enrichment was set to 100%. I set it to zero and seemed to have gained a ton of power and the off idle stumble is gone. Good stuff IMO. Maybe my AFRs at idle will stabilize out a bit too, I need to check that but it wouldn't surprise me if a bit of TPS noise was making it dump fuel.

These were on a 383 I bought. No way I would have paid new money for them, possibly even used money. It's the easiest place for me to gain power if I start looking to modify this engine. If I wasn't running a HSR which had 86 pattern heads I'd end up with something more Vortec style probably.

 

Apparently there's a setting for closed loop IAC. Who wants that is beyond me. I changed the setting, it let me actually bump the counts up some and off I went. Seems to be really darn decent now, I'm at about 1K out of gear and 750 in gear. I may pull it down a bit more but not really sure.

Took it out a bunch today, probably about 40-50 miles. Running really well.

 

Did some more work on this. I was having issues with getting up to a light and it dropping down in RPM. Really down. I started looking at the data logs and saw stuff was going super lean as in off the scale. I threw some fuel in and got good results. Just a reminder not to neglect the edges and corners of the fueling table.