Re: Ford 302 from 2 barrel to 4 barrel, is it worth it ?
The first engine I rebuilt was a 302 for a 69 mustang car. With stock manifold and 600CFM holley 4bbl carb the difference was from 190 HP to about 220. I just sold a 67 CorrectCraft Mustang with a 289 (302 with slightly shorter stroke) It had a stock 2 bbl at 190hp. Correct Craft rated the 4 bbl at 210. If you can find the Marine carb and manifold cheap it may be worth it. For new parts is 20 to 30hp worth $600. You can probably get away with the same prop. Note, if you start looking at new cam, 351 heads (they are semi hemi and were used on the ford BOSS 302) you are now looking in the range of 290HP with a lot more stress on the engine. This is close to 1HP/cu/in. Not many engines achieve that. The BOSS 302 used 4 bolt main bearings instead of the stock 2 bolt mains. As others mentioned with all that additional HP you will be turning your prop to fast and will need to find a new prop. A prop shop can help calculate what you will need but that will add another 300 to $400. And add the new heads, and cam so that the big valves in the 351 heads can breath, and now you're in the 1200 to $1500 range. It is a lot of work unless you really need it. My suggestion for is go for a Mallory marine elctronic ignition. It will give your great starts and consistent running all year long.