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merc #5 swap to #6???

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Old 07-10-2007, 10:51 AM
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Default merc #5 swap to #6???

im looking to swap my #5 drives to new #6's, does anyone know if the transom plates bolts match up or am i going to have to drill new holes? also can i run the same transmissions i currently run huber 1450's.
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Old 07-10-2007, 11:02 AM
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You will need to drill new holes. Maybe move the engine. With the engine movement is exhaust changes, hoses changing length. Transmission may have to change - plug in vs driveline.

All can be done but it is not a simple/cheap job.
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Old 07-10-2007, 11:03 AM
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i know the tranny will work i think the hole and pattern is differnt for the six good luck
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Old 07-10-2007, 09:22 PM
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There are assumed facts that may influence your decision.

1. #6's wiegh 180# more than #5's on box's,including 4 steering rams,transom stand offs for ram attachment, wing plates and tie bar.
2. CG will change proportional to the hull wt. and length.

3. Tail pipes , driveline length and motor mounts may require relocating.

4. The # 6 and # 5 bolt patterns are not the same. Plug the #5 holes, Drill the #6 holes and cut a larger transom hole.

5. Transom may require reinforcement (thickening) to produce equal rigitity. A four ram steering system, on wing plates, also uses those rams as gussets to reduce transom flex.

The #5's are rated at 750 HP w/1.125 lower gears and any ratio uppers. Uppers w/1.50 near net forged gears and 1.125 lowers have been run behind big power in heavy "V" bottoms w/minimum problems and considered strongest,#5's. The final ratio for that combination is 1.68. There are other options, to get in the middle.

As a suggestion, install four ram steering w/marine machine wing plates ,stand off box's,raise the drives 1" in the box provided holes and you will have a different boat. If that idea is not acceptable, trade for a boat with 6's,IMHO.

Trivia: #5's on box's and #6's place the prop at the same distance from the transom. It is said, #5's can be dry sumped.
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Old 07-10-2007, 10:15 PM
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I have been putting over 900 into 5's with net forged gears and have had excellent results. I also heard due to the footprint of the six it is actually a slower drive than a five for that reason.
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