A 3 second crank-time is probably not enough.
With the
[email protected] volts,you might be down to 250rpm at your Scr and locked timing, maybe less even. That comes to only 12 revolutions for you to learn what she wants.
With a longer crank-time, you might luck into it a time or two, and then things will fall into place.IMO, it's just learning on your part.
I've never had a 12.5 monster, so I'd be guessing if I said your T-port sync might have something to do with it. If the throttle was too far closed, there might not be enough fuel being delivered from the transfers to sustain her....... without a choke.
With lessor engines, insufficient T-port exposure is a common condition/mistake. Too much low-speed timing on lessor engines usually leads to such a condition.
Big cams usually sort that out tho. Like I said; I'd be guessing.
A lot of the fuel that you pump into her before beginning to crank her is just gonna lay on the plenum floor, or it will get stuck on the runner walls. Once it makes its way into the chamber a lot of the droplets are too big to burn and so they go right out into the exhaust, unburned.The only fuel that burns is the stuff that evaporated, or got and stayed emulsified. So at this time, the A/F ratio needs to be supper fat. Once the engine jumps to life, all this fuel hanging around will soon get ripped off or up and pass thru the engine, some of it sustaining the burn.But there will be a lot more of it coming until the intake warms up.
If the transfers won't deliver, you will have to keep pumping the pedal, and the fuel that comes from that circuit is not emulsified very well, and a lot of it too will pass thru unburned.....until the intake warms up.
Now a 50* ambient isn't all that cool, so, the above scenario will be eased somewhat. But really, as one poster mentioned, the throttle should be cracked to give the transfers a chance to deliver.
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I don't have a choke on my 10.9Scr, HO 367 either, but I have learned her personality after 15 or so, years, and I have a dial-back,dash-mounted, timing device. I can pull timing from the cabin, firing the mixture as the piston is going down, for a second or two, to get the starter rpm up. Then crank it back in, and even adding timing during the warm-up period. It has a range of 15 degrees. I set it somewhere in the middle. But it still won't total 28 like yours. I might get 3*mechanical,plus the 14* initial,plus 7* in the dial-back,totalling 24ish; and if I crack the throttle,and bring the Rs up to 1500 or so, then she will pull in
up to another 22* from the Vcan. I can tell she really likes that as it happens. So during the warm-up period; that totals
up to as much as 46*, depending on the running vacuum, at the spark-port, and as little as 31* if I fully retard the db.
She runs a power-timing of 34* at 3400rpm with aluminum heads and all timings normalized. It cruises at 14 initial plus 11* mechanical, plus 22* in the can =47* @2250 rpm and I can add up to 7* with the DB, for a grand total of 54* during cruising..
On the street, that Vcan is a real tuning treat, when.... or IF, you can get it bugged out. I have never worked on a street-combo that did not benefit from having one. But I have read of some here on FABO, that did not.
I only work on streeters.
