Mercury Mark 40H vs. Mark 40

[1bkshlf1]

Is there any difference between a Mercury Mark 40 and 40 H besides lower units? I just got a 40H with the quickie lower unit for racing, and now trying to find parts manual and users manual. It’s a 1955 and has not been used in 20+ years. It is frozen, but I don’t know to what extent except its been in only fresh water and it ran last time it was used on D hydro. Thanks,

[munimula]

The Mark40H powerhead and the Mark 40 fishing version were essentially the same. The only difference between the two was the 40H had an external tube connecting the pressure valve and the crankcase, through the top main bearing locking screw. Part # M-10-1358 Pressure relief hose – along with the necessary connectors.
You can find a scan of the service and parts manual over on John’s Old Mercury

• This reply was modified 3 years, 9 months ago by munimula.

[Nicholas Keller]

Also,others may correct me if I’m wrong, but I believe with the mark series motors the service motors with electric start had charging coils where as the H models usually did not thus reducing magnetic drag on the flywheel which is also why the hoprsepower ratings usually had a + after them.

I’m no merc expert but that is what I have been told, again if I’m inaccurate please feel free to correct me.

[dave-bernard]

the + was for the RPM’S higher RPM’S gave more HP.

[1bkshlf1]

Thanks to you for your responses, you’re helping a fledgling motor head.

Now, I need to know if there is anyone out there who knows whom I can contact about rebuilding this 40H to a running motor. It is frozen, but has been in storage for a few decades in Minnesota. The owner had the Quickie Lower Unit rebuilt 2 years before he quit using it on the lake (neighbors complained of noise). It hasn’t been raced, but it was on a D Hydro and was running without issues the last time he had it out on the lake..

If anyone can recommend a mechanic who would / could take on this project, I would appreciate the recommendation.

Thanks, again

Steve
949-642-5619 (Home land line) 714 273-7488 Cell/Text
Esso76@att.net

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