Offshoreonly.com - merc #5 swap to #6???

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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.
thanks

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.

i know the tranny will work i think the hole and pattern is differnt for the six good luck

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.

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.