Have a 1990 Sea Ray 220 Cuddy with 5.7 260hp Merc with slightly less than 400hrs on it. Thinking about getting rid of the Q-jet. Tired of the leak down/ flooding issues with the Q-jet. Looking at the Holley 4175 Q-jet replacement carb or a 650 Speed Demon with vac secondaries. If I go the Demon route I will replace the intake manifold with a Edelbrock Performer RPM ( recommend other?) manifold. I like the design of the Demon. Seems like it is a higher quality unit. I've also heard that the Demon carbs atomize the fuel better. Maybe has fuel consumption similar to the Q-jet? I typically cruise at 3200 -3500. Occasionally run at 4000rpm. Only rarely WOT to check top speed, performance, prop, ect and even then just a short burst. OR would rebuilding the Q-jet and JB Welding those spots on the Q-jet get rid of the leak down problems? Would I notice any increase in power or would it feel torquier with the Demon/ Edelbrock combo? Thanks.

I've used both BG and Holley, and I would give the nod to the BG (demons) They are basically the same carb, but the Barry Grants take the same idea and refine it. Machined metering blocks, better castings, etc. Its all little details. If you put them next to each other, the Demons look like a much more refined carb.

I vote Demon, but then again I might be biased

From what I can tell, about all you'll be gaining is no leakdown. If you just go with the Holley, you'll probably lose performance and fuel economy (with the stock manifold).

With the Demon (or any other Holley 4150 clone and new intake) you'll gain a little performance but only because of the better intake. You will lose fuel economy. Proabably by a significant margin. It's hard to beat the spreadbore Q-jet for economy.

Don't know anything about fixing the leakdown issue. Never really bothered me much. Just a few extra seconds of cranking at the beginning of the weekend. Only switched to a Holley because the engine combo was more than the old carb could handle

I am happy with my demon 825. I did not notice any gains from my holley.

Just fix the Q-Jet and save the money for gas unless performance gains are a secondary goal.

I am a Barry Grant dealer if you need assistance in choosing the correct carb. Thanks!

Dean Gellner
Gellner Engineering Marine Power

Of course some performance gain is a secondary consideration. I realize it will be slight. And from what I've found the Demon will be slightly better in fuel economy than the Holley.