Really? 2 pages on oil level and how to install a dipstick tube?

I guess all idling issues are not solved with these electronic carbs.
Electronic or old school carbs seem to require some tuning.

Anyhow - fiddling with cars is half of the fun

Cheers

I would not consider my situation normal and measure all Sniper installations by this. I could have left the direct linkage alone and it would be fine if this were a hot rod. My problem is this is a 390 in a daily driver F100 I built for my daughter.

The reality is, after it’s warmed up for 3 minutes or so, everything is perfect. In warmer months, it’s a non-issue. My problem is, I want it perfect all the time.

Did you check all the wires with an ohmmeter?

I really doubt it’s a dual plane issue, if you think it is, slap a 1 inch open spacer under it and see what it does

I think vacuum leak or dead wires

Swapped wires...same issue. New plugs, cap and rotor.

I believe the issue is the progressive linkage on the Sniper. This is a change from stock to alleviate the abrupt tip-in the Sniper has because all four throttle blades roll in together. I have modified the software and added a progressive link that starts activating the rear blades at about 40% of the fronts, to act more like a 4-barrel (and keep my daughter from unexpectedly lighting up the tires). This change and link is available from Holley, but “not advised”. Well, the damn thing is way too touchy with all four barrels opening together.

Anyway, the rear barrels have no fuel being introduced at idle now. I currently have a 4 hole, 1 inch spacer that may be making it worse. The Sniper injects fuel above the blades, so it bounces off the blades, pools momentarily, and then gets sucked in.

I think I have a lot of pooling and condensing going on in the plenum at cold start. 3 minutes later and all is good.

I’m going to try an open 1” spacer instead of the 4 hole. The problem is, the Sniper is known to have an annoying whistle related to the IAC in this configuration. If the cold fuel distribution is better but I get the whistle, I’ll add a 1/8” steel 4 hole plate between the spacer and the throttle body.

Certainly sounds like an EFI issue.
I have never liked the electronic carb type efi.
I prefer individual injectors for each cylinder.

I am sure you will figure this out. Have you sent a message to Holley?

I’m a member on their forums...I posted over there, yes. I’m concerned that the progressive linkage and programming I have added may be the issue (even though offered by Holley). The rear two injectors do not flow during idle...at all.

I’m also using a a 4 hole carb insulator that could be contributing, as opposed to an open spacer. I don’t know.

Yes, I have a set of leak-down gauges. Not a bad idea to confirm before I just start resetting the lash.

This morning I checked the temperature of the header pipes just after starting the motor.

Cylinders 3,4,7,8 are running cold at initial start. After warming for 2 minutes, all fine.

For the record, it’s a dual plane.

I’ll report once I get the covers off, but it looks like I’ll be re-setting all of them.

I find it strange that I’m not getting any popping through the carb, if it was a procedural thing.

Are you sure you're not getting icing on or in the carb?.....

No carb on this one! 

There's about .100-.125" of travel in a traditional, standard travel, hydraulic roller lifter.   I've seen some guys struggle with getting the pushrod lengths correct on short-travel lifters with non-adjustable rockers, but unless you really messed up on pushrod length measurement, I don't see it hanging a valve open when it's cold.

I know, that’s what I don’t get...and I have adjustable rockers! There should be no way that I got that much preload. It absolutely sounds like it though.
Listened to it again this morning and put my hand up to the exhaust. Sure enough, nice strong puff associated with the stumble. Once the temp is beyond 135, it purrs like a kitten...clean and smooth.
I was just looking for input on what I could be missing before I pull the covers.