Cold starting issues Choke

"I repowered my boat this year

"I repowered my boat this year with a used (1992?) Mercruiser 350 Mag 4bbl carb (not sure what brand carb, boat not here to look at). It runs great when warm and starts in neutral with a touch if it's been run recently, like sitting on the water for lunch or between tubers. When warm, it idles nicely around 600 rpm on my tach. So, the only problem is cold starts.

Cold start, I use the same technique I used for my 1985 305 which started great: I give it two full throttle shots then leave it around 1/3 throttle. It seems to start briefly then conks out almost immediately. After this, the only way it will start is full throttle with a VOOM then I quickly trottle back to 1000-1200 rpm. Any less and it conks out again - in neutral it goes down to 400 rpm, sputters and dies. There is blackish smoke coming out when it starts this way also. Only after many minutes can I put it in neutral to idle.

One mechanic just wired open the choke and I ran it like that for a month or so, but it still didn't start great, maybe it did warm up a bit faster. I recently unwired it and replaced the spring coil (bi-metal temp sensitive I think). The old one was pretty rusty looking so i assumed it was the culprit. No noticeable improvement, unfortunately. This spring control does not look adjustable to me - is it? The links to the choke plate seem to move freely.

The carb has been rebuilt so i assume it's working fine. I see shots of gas going into the carb when I advance the throttle, so that seems to be OK. The engine runs fine when warm. Any ideas what to check first? Is it bad for the engine to be started the way I am currently (I remember sometimes using the same procedure for my dad's 1980 Impalla with the same engine)?

Thanks."

"The choke is adjustable. Wit

"The choke is adjustable. With a cold engine, on a carb mounted choke loosen the 3 choke screws and turn the insert in the direction that moves the throttle plate until it closes al the way but 1/8". While doing it hold the throttle lever just a ahir off the throttle stop.

If the choke coil sits in a bowl on the intake, just bend the arm a little at a time until the choke plate is open 1/8". Lift the bowl out of the manifold and clean the bottom of the bowl. If the bowl sits over an exhaust passage I'll bet the passage is plugged or narrowed. Usually the manifold is boiled by a radiator shop to clean it. You can try w/a can of carb cleaner and a flexible wire bristle brush."

"OK, thanks Guy, I'll give

"OK, thanks Guy, I'll give it a try. Only question is what IS a "cold" engine for these adjustments? Is an engine that has sat for a day "cold" even if the outside temp is 80 deg.? Or would that then make the choke "too closed" when the outside temp is say 60 deg? OR does it not matter?

Thanks."

A cold engine has not been run

A cold engine has not been run for a day in the summer. Open the engine bay and provide shade for it to remain at air temp.