Re: 2bbl to 4bbl conversion - is it worth it?
Oh man that's a lot of questions.<br /><br />First: Whatever you do, get a marine carb. Auto carb can slosh fuel which will collect in the bilge and can RUIN your day.<br /><br />Personally I prefer holley, because they are pretty simple to work on. Rochesters work fine, but it takes a pro to rebuild one. Keep in mind you'll need an external fuel filter if you go with a holley. BTW expect to pay close to $500 for a new marine 4v carb.<br /><br />Fuel milage. You can get a bit better milage with a 4v because (usually) the 2 primary barrels are somewhat smaller than a 2v carb. BUT if you run fast enough so that the secondaries open, forget it, you'll get worse milage. Or if you do a lot of full-throttle starts (and who doesn't?).<br /><br />As for the power gain, it won't be as much as you think, unless your 2v is not adjusted properly or needs rebuilding. Maybe 15-30hp. My opinion: Not worth it, unless you need to replace the old carb and manifold anyway. Be warned that you can easily loose performance if the carb is not properly matched/jetted. Don't put a 750DP on a 302 (unless you are gonna run 8000 RPM). Probably a 450 would be fine, MAYBE a 600. In fact I think Holley makes a 450 specifically for the 302 Ford marine application.<br /><br />Aluminum vs. Cast Iron: Well with Aluminum you get better designs for performance, They are a few pound lighter, but possible corrosion problems, espically in salt water. Iron you got possible rust problems. My opinion: Iron for salt water, Alum for fresh.<br /><br />Single plane vs 2-plane. Generally, single plane gets you better high-RPM horsepower, 2-plan gets you better low-end torque. If you pull skiiers a lot and need torque, go for a 2-plane, otherwise a single plane is probably better for marine apps. The cam profile can affect this as well, but that's another big bucket of worms.<br /><br />Good luck!<br /><br />Tom
