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Thread: Need help building my 400 small block.

  1. #1
    I've build a bunch of motors for cars, but none for marine use. I've got a 21' 1985 Scarab with a stock 350 in it now. It will run 59 on the GPS. I've got a 400 block and crank laying in the garage that I'd like to build for this boat. I know that with a marine motor you want to make the power down low and peak out around 5000rpms. Can someone give me some info on the type of cam, heads, and compression that I should run. I think CompCams makes a 264 X-treme marine cam that might work OK. What do you think? How much power should it make? Will it tear up my Aplha drive?

  2. #2
    You could make 500 hp out of that thing easy. I suggest that you get pistons that use 350 rods. They're longer and more widely available. Just find a set of 882, 041, or 441 heads. Then hog the exhaust out for 1.6 valves but stay with 1.94 intakes. That 264 cam would work well but I'd go a little bigger. Comp should end up around 10-1. This way you can run pump gas. Make sure you port the heads and mirror polish the combustion chambers. Where are you located at? Maybe I could make a trip there (if it's in SoCal) and teach you how to port heads. I'm always happy to help people out. E-mail me if you have any other Q's.

  3. #3
    Motor Magic 562-925-9261

  4. #4
    I have a set of heads I'd like to get rid of.Darts, new in box,bare,cast iron, $450.

  5. #5
    Junior Member
    Join Date
    Mar 2010
    i have a set of 441's for sale. need rebuilt.

  6. #6
    you basically build your engine as you would for a 4x4. TORQUE

  7. #7
    A bunch of people have told me that if I go with to big a cam it will cause reversion. I have stock merc manifolds and thru transom exhaust. What size cam would be to big? Would one of those CompCams E-treme torque 4x4 cams work, or should I stick with a marine cam? Thanks again.

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