I'm building a twin turbo 350 based stern drive application which will be a very low boost (6-8 PSI) deal. On my street cars, I have had outstanding experience with Summit's reincarnated Holley 4010 which was reincarnated from an Autolite 4100. I'm curious if anyone has modified one of these for blow thru operation? They have one big advantage in a marine environment, they don't leak fuel when changing jets! That's a bigger deal when you have a closed engine compartment with poor ventilation off plane. They already have the annular boosters favored in blow thru applications and they are available in a 750 DP configuration. I've used CSU Holley based carbs on 800 plus HP blown marine applications, but was looking for something more modest (and cheaper) for this modest boat.

I've tried to contact a few shops regarding this carb, but no one responds. I understand it if it is something they are not used to, but I would like to try one.

 

I've seen these (I imagine they are the ones with the top that pops off closer to a Carter) but here's my thoughts:

-How hard is it to enlarge the PV passages and are there any limits
-Is it mechanical secondary? If not you'll have to figure out how to deal with the vac secondaries
-What are your float options available? You'll want something that won't crush otherwise you're modding something
-Is the emulsion circuitry easy to access? You may need to reduce it if you lean out up top
-There's probably a power valve blowout eliminator if it's Holley that you'll end up having to deal with (aka remove.)

Just some general thoughts that may get you going the right direction. Not sure if someone here will chime up with specifics or not. I'm guessing you're referring to this carb though.

https://www.summitracing.com/parts/sum-m08750ms/overview/

 

All good points!
There are both VS and DP's available in that design. I used the 4010 750 DP on my old boat with success. In speaking to one particular carb shop, there was concern that higher boost levels might distort the top plate to the point of allowing fuel to escape between the body of the carb and the base housing. The internals are retained from the 4010 Holley, although I have never opened one of my Summits up. If I could find a DP version cheap, I might pick one up to experiment, since I use a wideband O2 to tune. I've seen many low hour BAN Quick Fuels being sold in the $550-$650 range (don't know if this is bad or good), so I wouldn't go too far in spending $$$ on a Summit carb. One thing is certain, I'm NOT spending a grand or more on a docile, 6 PSI low boost blow thru carb. Now if we were talking BIG power, that's another story.