1971 40hp mercury comments? reliable motor?

[dkonrai]

i lucked out and got this free motor, mercury 40 hp 1971 motor (just found this out) i know it runs, got it from a buddy that is a pt marine mechanic. compression is good, she has 175 pounds of compression in both bores

question is are these pretty good motors? seems like a tank (really heavy) and it will be replacing a 86' force 50hp.

will performance be close? last outing before i blew a piston was 30mph (gps) on a 14 foot 86 bayliner. not that i want to race around, but just curious.

thanks
dino

 

[Maxz695]

Re: 1971 40hp mercury comments? reliable motor?

working with another poster no spark parts expensive and extreemly hard to find 1971 switchbox, but if it,s all good it,s a merc and therefore alright with me. bayliner hulls are relativeley thin 1/2 inch thick as opposed to a wellcraft 1976 nova 3/4 inch thick therefore it might be ok the HP is a bit low but with the proper prop it may plane fine is it a long shaft I hope and is the transome on thboat suitible for a short shaft ? lower than star8 across or almost str8 across?it needs to be way low on the transome for this engine to work without vetilating (Cavitating)

 

[dkonrai]

Re: 1971 40hp mercury comments? reliable motor?

yes the 71 is a long shaft. i will measure the boat tomorrow, and check to see if my usmarine controls will work with the merc cable ends.
dino

 

[Faztbullet]

Re: 1971 40hp mercury comments? reliable motor?

Other than the electronic's issue it a pretty good motor. Make sure you have a tach as the 40 & 402 are bad about crank breakage if lugged. Minium rpm is 4500rpm.

 

[RRitt]

Re: 1971 40hp mercury comments? reliable motor?

Mercury will discontinue parts when they want you to buy a new motor.

 

[dkonrai]

Re: 1971 40hp mercury comments? reliable motor?

Mercury will discontinue parts when they want you to buy a new motor.

i think all of the companies do this. that is the reason ebay does so well?
dino

 

[Maxz695]

Re: 1971 40hp mercury comments? reliable motor?

also why i,m lowering pitch from 11 x 12 to 12 X 11 was only getting 5000 top RPM