Welcome back as always,

Today we are taking a deep dive into the items necessary in order to complete a successful 40/50 HP to 60 HP conversion on a #mercurymarine and going over their respective locations. This conversion can be done successfully on both engines AS LONG as they are 4 cylinder 995cc engines. This mod cannot be done to the smaller 3 cylinder 40 HP engines.

Items required to complete a successful 60 HP conversion free of issues:
- 60 HP PCM new or used (used is preferred as it does not require intial PCM setup at a Mercury authorized dealer and is generally found much cheaper
- Restrictor ring removal
- Propeller change out of the OE Blackmax

Propeller pitch size will vary based upon what is required for your particular load and I HIGHLY recommend a stainless steel preferably of the Mercury brand in order to stay compliant within the specified RPM range of 5500-6000 RPM. I currently run 6100-6200 with my 4 blade Trophy Sport 10.625 x 14 pitch with zero issues, and no Guardian intervention, so you will be safe to be slightly higher. Bear in mind, a jackplated setup will increase RPM by about 100 - 150 RPM of whatever the propeller would spin nominally at WOT otherwise.

The 995cc #mercury powerhead is based off the 70 HP #yamaha powerhead and the F70 is specified to make its horsepower at 5800 RPM as per the Yamaha website, so I STRONGLY recommend you stay on the hot side over the lower side of the RPM powerband. Do not be afraid of high RPM. It is required to make power and to keep from lugging your lower gearbox and decreasing its overall service life.

For help sizing your prop, I would be happy to help if you do not know what to do, feel free to drop me a comment and we'll go from there.

I will need your CURRENT:

- Max RPM at wide open throttle
- Max speed at wide open throttle
- Current prop pitch

IMPORTANT SIDENOTE: The 40 HP 4 cylinder version model Mercury outboards come equipped standard with a 2.33:1 Command Thrust PCM. I did not realize this at the time of making this video so the requirements for your engine change. In order to successfully complete this conversion, you will need to obtain a 60 HP Command Thrusts/ Bigfoot variant PCM. Propeller pitch will also vary from what is shown in this video!

Extras:

I did not discuss this in the video, and it is optional, but for those running Champion copper spark plugs, I recommend NGK part number: BPR6EIX/ 6637 spark plugs for longest service life/ hottest spark/ easier ignitability for coils.

Resources:

- https://public-mercurymarine.sysonlin... sysname=NorthAmerica&company=Guest&NA_KEY=NA_KEY_VALUE&langIF=eng&langDB=eng
- http://www.mercurymarine.com/en/us/pr...
- https://outboardcovers.com/

Lets get you out there!

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