1957 Mercury Mark Thunderbolt 40hp INFO/HELP

[Squirrel42]

I just picked up a fully Restored (to my knowledge) Mercury Mark thunderbolt 40hp
Very Familiar with rebuilding Evinrudes and Johnsons.
I know nothing about Mercury

What is the Fuel Mixture for the 40hp?
Can I use my Evinrude fuel tank and fuel line with the mercury as long as I trade out the fuel connector to the engine. Do I have to change out the connection on the tank side?

Anyone know if they get better gas mileage than the Old Evinrude Big Twin 1957 35hp?

Good Merc sites are appreciated !

 

[jimmbo]

39.6 cu inches.
Bore 2 7/16"
Stroke 2 1/8"
WOT Rpms 5200 - 5800
Gas Oil ratio 20:1

The engine doesn't care what brand of fuel tank is used, as long as you use a non-pressurized evinrude tank. The 57 35hp had a pressurized tank.
Performace between the bigtwin 35. Well, the 35hp had a displacement, of 40.5 cubic inches and was rated @ 4500, with a WOT range of 4000 - 5000 rpm. The Mercury was 39,6 cubic inches and was rated @ ???? WOT range was 5200 - 5800. I would think the merc made a lot more power than the Evinrude. Even the evinrude 40hp only had about 3 more cubic inches, but was still rated at 4500 and a range of 4000 - 5000 rpm
Fuel economy? If both engines were run wide open, the E35 would burn less fuel per hour, because it is not turning as fast. I suspect the M40 would push the boat faster and if slowed down to match the speed of the E35 it would be burning less gas.

Thunderbolt was a reference to the ignition system

 

[Chinewalker]

Both motors from that era were a little thirsty by modern standards. Mercs tended to be a bit harder to work on with a steeper learning curve and a few special tools required for basic service. It's possible to improvise for some of these (water pump cover removal tool) and others are available (timing plate for setting point dwell, etc.) online. The Mercs seem to have a bit of cachet to it that the Evinrudes and Johnsons don't have. If your Evinrude has been converted to a fuel pump, then you can use that tank with the Mark 55. If you're still using a pressure tank, then no, you won't be able to. Any single line, vented tank will work with the Merc if you use the standard Mercury twist-connector.

FYI - Thunderbolt was not yet referring to the ignition during the 1950s. Mercury would name their cylinder block families. They had the Hurricane (20 cube), Super Hurricane (22 cube), Turbo-4 (30 cube), Thunderbolt (40 cube), Super-Thunderbolt (44-cube), Marathon (60 cube), and Super-Marathon (66 cube) blocks during the 1950s. They continued this practice on some blocks well into the 1960s. They had stopped referring to the 44-cuber as the Super Thunderbolt by the time they started referring to their electronic CD ignition systems as Thunderbolt in the late 1960s.

 

[Squirrel42]

No Title

Engine Model is a Mark 55

Thank you for the response to my ridiculously stupid questions.. I was not sure if it was a pressurized tank or not, I found the fuel pump and the fuel line connector in a box of parts and and got her running after three pulls.

I really hit the mother load with extra goodies.

The purchase came with all the mercury tools for water pump & lower unit gear removal, pullers, yankers, extra wiring harnesses, a boat load of extra parts, new engine stand, even an extra engine for more spare parts along with 2 Lower units. I could not have asked for a better find at $300, I feel like i got a great deal. Even had the new decals!

Here is the BAD news.

When I started her up for the first time, she ran for a second and slammed into reverse throwing all the water from the tank. I had to hold it in neutral to keep it from slamming into reverse again. So now i am attempting to remove the lower unit and inspect the gears. This was a complete rebuild by a gentlemen that passed away before he finished. I have no idea what he might have left out. From what i could tell he was shy of a clear coat and new decals.

It wouldn't even go into forward with out a grinding sound, so I'm not looking forward to the inside.

I drained the Lower unit and only saw one little flake of metal, not sure if it's a good or bad sign, any metal shavings is BAD!!!

 

[racerone]

When control and cables are hooked up it will not jump into reverse.-----I say there is nothing wrong here.

 

[Squirrel42]

Is that something that is normal for an old mercury? I'm only familiar with old Tiller motors, so cables and controls are a new ball game.

What about not going into forward gear?


It was a clicking/grinding sound when I attempted to shift into forward gear, I only tried to shift into forward once, I didn't want to further damage anything. Could this be something with the shift connection, possibly an adjustment?

Is 80w90 gear oil ok to be running in this gear case. I run it on my 1957 35hp evinrude with no problems,. so far.

 

[Squirrel42]

No Title

So looking over the lower unit, I see there is a spacer missing above the two reverse lock cams, could this possibly be the missing link?
I'm only seeing this through a exploded diagram, not sure if this motor had one.

 

[Chinewalker]

That gizmo on top of the unit is the reverse lock to prevent the motor from kicking up in reverse, but allowing it to tilt in neutral or forward. If all the bits aren't there, it may not lock, or will lock when it shouldn't.

Hmmm, usually they jump into forward gear, as the lower units are spring-loaded to forward on the shift clutch. You would need some force to push it into reverse. UNLESS you have the wrong propeller? Not probable, but possible. Original prop was right hand rotation for forward.

 

[DeepCMark58A]

So looking over the lower unit, I see there is a spacer missing above the two reverse lock cams, could this possibly be the missing link?
I'm only seeing this through a exploded diagram, not sure if this motor had one.

​The two parts you are showing are reversed, the part with ears goes on top.

 

[DeepCMark58A]

With it upside down it is bound to be part of the problem no spacer needed.

 

[Squirrel42]

It takes no pressure to put into reverse, where it's really hard to pull into farward and just wont go into forward while running. Something with the shift rod maybe?

I'm having a hard time finding a diagram of how it's installed correctly, but i think i have figured it out when I flipped them around.

I guess i'll put it back together and try again with cables installed.

 

[DeepCMark58A]

There is another website that specializes in old mercury motors, this site is awesome but john's old mercury has the diagrams making it worth the $15 a year.

 

[DeepCMark58A]

Put it all the way clockwise in forward on the lower unit gear, put the lower piece on the splines so the upper piece with the dogs fits into the receiver part on the upper unit. Put it together and feel from the bottom so the shift shaft mates up, should slide together with some wiggling.

 

[Squirrel42]

I saw that site DeepCMark58A..I might give in at some point if i have to rebuild the top. I found a manual with the correct exploded diagram that shows the correct position of the cams. No spacer needed in the diagram, that is a relief!

Forward Gear - Ratchets clockwise and locks up counter clockwise

Reverse Gear - ratchets Counter clockwise and locks up clockwise

Is this correct?

 

[Squirrel42]

Now here's a stupid question..

When i connected the cables, I realized that Forward pulls the shiftier on the engine towards the rear and Reverse pushes the lever towards the front of engine.

This is backwards from the Evinrude shift levers.. Is this correct?

 

[DeepCMark58A]

Yes that is correct

 

[Johnson110]

I always used to hear that Mercury had to be different ( engineering) with the the outboards.

 

[Squirrel42]

I got everything put back together and still wont shift into Reverse.

At one point I got it into reverse and the Prop shaft locked up, It wouldn't ratchet either way. Seemed strange since i was told it should ratchet.

Has no trouble going into neutral or forward. It's a complete restore, so i was doubting there would be any problems in the lower unit, man was I wrong.

Any videos on pulling the lower unit gears on the old Vintage Mercurys? I have all the tools and pullers!!

 

[DeepCMark58A]

Tell you what don't tear it down yet. I have pretty close to the same motor, exact same lower unit. I only know some about it by making mistakes and a lack of luck. I shipped my lower unit to a lower unit off to an expert because I was sure there was a problem with only having forward and reverse, he got back to me last night that there indeed was no problem. I will be going up to his place to reinstall the lower unit. I will be taking notes and taking pictures on the proper install sequence. It sounds like you are in the same boat together.

 

[Chinewalker]

Does the lower unit shift with it off the motor? A rag wrapped around the shaft and a pair of pliers to grip. See if it shifts easily into all three positions. If so, then your issue is elsewhere. Also, there should be a stop in the shift/throttle linkage to prevent shifting if the throttle is advanced too far.