TOPIC: 1967 merc 650

Well I just picked up a 1967 merc 650 for $400 I have no idea if it runs, but the thing looks like it just came off the show room floor. I was told it was hardly used and was only taken off the boat because they got an 85hp about six years ago to better pull a skier. He told me it also has a lowerunit of a mid 70's 85hp merc. Assuming it does run and I turn out to not be a sucker. Is there any thing I should check besides the compression, impeller and the lowerunit oil? I will post pictures of it as soon as its on the stand and out of the bed of my truck. P.S. his story was very convincing. Also I bought it to replace a 71 merc 650 thunderbolt. which do you think is better or are they pretty much the same.

save the 71 for parts.

Do you realize the gain in:
"He told me it also has a lowerunit of a mid 70's 85hp merc."
It will be a 2.31:1 ratio lower unit and will really make the 650 4 cyl rip the arms off your skiier.
You'll be up on plane quicker and the 650 will run in its power curve with ease with the right prop.
A very good retro-fit for the 650 4 cyl.
Thom

Hey Thom, Is there a bigger L/U that I could put on the 58A that would boost it up? Thx, Joe

here is a couple pictures of her, she is still a little dusty but it will shine up like a new penny

Jetflite,
That is a nice clean 650. DROOL-DROOL-DROOL.
Just be careful as your original 650 prop might not have enough pitch when using the 2.31:1 lower unit and you might over-rev the motor.

No Joe,...Nothing bigger or better to offer in the lower unit on a 58A.
Thom

WOW that is clean!!! I want it!!! And like Thom said the gear ratio never changed on the MK 55's 58's and early 400 500 type motors without thru prop exhaust.

They did make a Heavy Duty lower unit with a tapered roller bearing in the front of the gears instead of two roller bearings. The case is longer front to back. I have one on my 1961 500 merc. No gear ratio change tho.
Conrad

Been gone all afternoon til now. Thanks anyway. Joe

I just did a compression test and all four cylinders are 120psi I did look at the prop and its a 21p but it does't seem to be the right prop for the L/U

There is a locking washer that grabs the end of the splines that is not on your drive shaft in that pic. It goes between your prop and the bendy lock tab.
Conrad

Exciting new she LIVES just took a couple turns of the key and she fire right up and sound great The only thing I'm concerned about is the tattle tail stream seems to be weak at idle, but as you rev it up a little it seems to get a little better. Is this normal or is the impeller shot? Also does anyone use the tachometer plug on the control box and if so how good does it work and can I use any old tach with it?

get that impemeller repalced...my 50hp was exactly the same hardly anything when you ran it but spit out great higher revs...the tabs are probably starting to crack from sitting so long.....plus its a good insurance factor..spend the few bucks and replace.

Nice clean good looking Merc. Should pull like a tractor.
And I am with Matt, change the impellor. Quick and easy job and a chance to get acquainted with this little routine maintenance chore.
Neil

Well I pickup a 24 pitch 2 blade brass prop off ebay. But before I cut up my trim tab for clearance. Is this going to be to much prop for the motor or am I going to be over joyed at the increase in speed

you need any spare parts for this 650 ?
I have to 650 ? unsure of year but I believe they will be torn down and parted out ...

One I know the PSI was low across the board .. the other ? I will have to check...