Ok, I have scraped the small blocks for my Formula. I have a line on a couple of 454 blocks but they are two bolt mains. They are interested in swapping me the blocks for my 400 small block and vortec heads. My plans are to build mild motors for cruising with an occasional WOT run. Would the two bolt blocks hold up under marine conditions or should I hold out for 4 bolt mains. I dont want the extra expense of adding splayed mains. Also what would you recomend for the building these motors? Cam, head intake suggestions are greatly appreciated. I plan on using Bravo 1 outdrives.

Thanks

Watch the centerline measurement of the small blocks...BBs may not fit without major mods

The two-bolt mains are fine for your intended use. Be sure to have the blocks checked for cracks before sealing the deal.

The blocks have been mag'd. The boat transom, stringers, and floor are being replaced. I will be needing suggestions for centerline of the engines along with the X dimension of the drives. I will be completely rebuilding the boat. All this work for a bet. I will win my steak dinner...LOL

I also want to stay with Iron heads, aluminum are just out of my projected range at the moment, unless an absolutely insane deal falls my way.

Center line of 34-36 IN. 36 inches will work best for exhaust issues. For bravo drives you might contact Competition Marine Center in MO. Eagle makes a good stroker rotating assy to get 496 CU IN from your 454 blocks. Get the optional high strength ARP rod bolt option. For heads look at DART.

Mine are at 33" with Gils. I have to pull an engine to check plugs. The 2 bolt mains are good for 600hp if all the proper blueprinting is done and arp studs are used.

You can throw all the money you want at the stroker kits and high-dollar parts, but the simple truth is that GM stuff will make 500 horsepower and hold up very well. Good used parts such as cranks, rods and heads are available from engine shops here on the board.
By the way, there are a lot of people on OSO running two-bolt blocks, cast cranks, and rods with 3/8 bolts, and with dyno results in the 500-550 horsepower range. Quality machine work and a clean assembly process is where you can't cut corners.

Ok, I think 500-550HP NA is the goal. 454 two bolt mains. I need compresion recomendation , and which Chevrolet head should I look for? Also cam and intake suggestions. This is my first large boat project and I need all the advice I can get.

I do computer work for a local machine shop, Brand Racing Engines who will do all my machine work and my neighbor, Lynn Morris ports heads from his home. He does a lot of big block apps for national dragsters and local drag teams. So my machine work is taken care of. I just need to be on the lookout for the parts.

My buddies at the machine shop can give me good direction, I just want some more specialized advice since its a boat instead of a drag car.

Thanks for the input guys...
Steven

I understand that Dart Iron Eagles are a very good iron head right out of the box. Or let your neighbor go to work on some GM 088 or 990 castings.