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  1. #1
    Bo Knows

    Decided to modify my 330 hp 454's

    I've been undecided about modifing the motors in my boat so I thought if I could find 2 early GM high rise intakes I would go ahead with the rest of the plan. Last week I found them, so here's the plan. Checkmate 281 with twin 330hp 454's runs 66.7 mph on GPS. Installing GM high rise intakes, both ported and passage between primary & secondary cut out. Adding 1" spacer under carb. Port matching heads to intake, enlarging exhaust outlet port on head, porting heads completely. Keeping quadrajet carb but will richen up secondary. Installing Crane cams #133801, with lift 529 & 525, duration 222 - 234, & Crane valve springs. Anybody got any ideas, help or comments on what mph I can expect, or something I might have missed? I know I should up grade exhaust but can't afford it at this time. Hopefully at a later date. I'm just a poor man trying to play a rich mans game !!


  2. #2
    Charter Member #655 Charter Member dyno's Avatar
    My Boats:
    1993 Sonic 31ss
    Join Date
    Dec 2000
    Holland, Michigan
    sound like a good start then you can add exhaust and carbs later roller rockers are a big help too! I made a little more up grades to my 330's merlin heads ,carbs and exhaust and MSD ignitions I gained 10mph.
    If your boat has a sail do you ride a horse to the ramp?

  3. #3
    My Boats:
    '77 Martini 7 Meter
    Join Date
    Feb 2002
    Honeoye, NY
    Go to HPBOOKS-1297, " Big Block Chevy Marine Performance" by Dennis Moore. Just TONS of great info. What to do first, how much it should cost, important part #'s, just about everything you ever wanted to know about building a DEPENDABLE performance BB. --- Jer

  4. #4
    Join Date
    Nov 2000
    Glastonbury, CT
    I had the same motor in my 88 donzi. I did the same cam and lifiters and with a upraded timing chain from Crane. No changes to my valves except heavy duty push rods. Also but in forged piston. It was along time ago but the motor ran great and had a very nice sound to it. Also through on a High rise and a K &N filter.

  5. #5
    Registered bsag's Avatar
    My Boats:
    27 warlock
    Join Date
    Jul 2001
    cambridge, md
    This months family & performance boating has a good article on modifying the 330. Check it out.

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