Help Picking a Carb
03-07-2019, 05:10 PM
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Help Picking a Carb
A little out of my element here, as I have a fishing boat, but I am looking to have one with decent power and yall seem like the crowd to help me get it there. It is a Carolina Classic 25 that until a couple weeks ago was powered by a stock Volvo Penta 7.4L Gi, that has now been pulled and is waiting to be rebuilt with a focus on gaining power, as the 310 hp it had from the factory was not adequate for this boat that weighs in around 10,000 lbs when loaded for a bluewater trip. Between the pain in the ass it would be to have the MPI system tuned and the gremlins i had been dealing with in that system anyway, I have decided to move to a carb but have never dealt with one before and need some help figuring out what the differences are between the various models and which one to pick, Holley's marine line alone has the standard Holley, an Avenger, a Double Pumper and the Quick Fuel carb no to mention other makes as well and Holley's tech line was not much help in getting a breakdown of what the differences are between them and the advantages of one versus another. Could someone help me out with this information and recommendations for or against any of those or any other brand or model that I should look into? I have also even kicked around the idea of the Holley Sniper EFI, any good, bad or ugly on that? I realize I would need an O2 sensor for that (and really from reading on here about tuning, I would probably be best off with accommodations for one with a carb too) and am planning on a Stainless Marine exhaust system with a bung added in. I don't have a specific parts list for the engine build yet but the builder I have spoken with has a goal of about 450 hp/500 ft-lb torque and keeping it low in the RPM range, doubtful we will ever go much if any over 5,000 rpm, and most use will be in the 3500-4000 range or maybe a bit over. The builder suggested a 750 CFM Quick Fuel but I am the kind of person that likes to know the pros/cons and whys of things. Any suggestions, education, etc is greatly appreciated. As a side note, any info on what all I have ahead of myself getting the wiring and engine in general back in the boat and hooked up and going is appreciated as well.
03-08-2019, 09:49 AM
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I am a carb guy and have spent a lot of time fine tuning my carb to run just right. Not many people want to spend that kind of time pulling plugs and checking color to see if you have the jetting right. You already have the fuel delivery system for fuel injection, I would go with one of the throttle body systems on an Edelbrock RPM Air Gap intake. Find a unit that will handle the spark curve as well and you will be much happier. They're not much more than a good carb and by the time you buy a jet set and squirters and power valves you're probably saving money. FiTech seems to have nice units with really good reviews. If I didn't have to buy new headers to get an O2 bung and fuel pump, that's what I would do.
03-08-2019, 10:28 AM
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I hate carbs, but had a Quickfuel and was really impressed with it. I just rebuilt my engine and didn’t feel like ducking with the jetting all over again so I’m now installing the Holley Sniper. Another member here did the same and is pretty stoked with it.
I already have cmi headers and had a local welder put in a bung for me for $50, but in your case I’d go with manifolds. Emi Thunder and Stainless marine can both put a bung in for you at the factory.
I already have cmi headers and had a local welder put in a bung for me for $50, but in your case I’d go with manifolds. Emi Thunder and Stainless marine can both put a bung in for you at the factory.
03-13-2019, 05:54 AM
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Thanks for the info. I think I’m going to go with the Sniper, im
getting Stainless Marine manifolds and risers and will have a bung put in to take care of the O2 sensor, now just have to figure out adding a fuel return since the VP MPI didn’t use one
getting Stainless Marine manifolds and risers and will have a bung put in to take care of the O2 sensor, now just have to figure out adding a fuel return since the VP MPI didn’t use one
03-13-2019, 06:49 AM
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You can run the regulator bypass return to the water separator filter head if you have a port available -6an
03-13-2019, 07:26 AM
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03-13-2019, 02:12 PM
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I had seen that T for the fill neck earlier while looking around for options and was going to ask if anyone had tried that or if it was a frowned upon option. Same with routing it to the filter, does that seem to work fine as well? What about fuel lines, what seems to be the best, approved route with those?
