1965 Evinrude Big Twin 40HP (40502A or 3A)

Hi,

I am about to pull the trigger on a 1965 Evinrude Big Twin 40HP for about $60. The engine is in unknown condition. But since its been running in freshwater there should be no big issues with corrosion (looks quite good). The engine is a manual start with tiller handle. Only thing I know about the motor is a vague picture and some information that the carburator is in a bag on the side. So - from looking on marineengine.com and searching for different standard parts everything seems to still be available to order (like impellers, head gaskets, thermostats etc.)

Im not a complete newbe when it comes to engines. I have renovated a couple of 15hp 1985-87 engines without any big hassle. But my questions to you are what I should I lookout for before buying this engine?! Any knows problems that might cause this engine to be unrenovatable?

Another couple of question while I am at it:

- Whats the approx weight of the engine? (much heavier compared to a 15HP 85-87?)
- 40HP with rope start seems very heavy to start - anyone got experience about this engine with manual start?

// Mike

Re: 1965 Evinrude Big Twin 40HP (40502A or 3A)

See if you can test compression before buying...but for $60, you've got your money back in parts/scrap.

I'm guessing about 125 lbs.

Pull start a 40hp? Get her tuned up really good and buy a good pair of gloves. A poor starting pull start will kill your hands and shoulder!

Mas

Re: 1965 Evinrude Big Twin 40HP (40502A or 3A)

Mas said:

See if you can test compression before buying...but for $60, you've got your money back in parts/scrap.

I'm guessing about 125 lbs.

Pull start a 40hp? Get her tuned up really good and buy a good pair of gloves. A poor starting pull start will kill your hands and shoulder!

Mas

Click to expand...

Yea, definitely want to have it tuned up right if its a 40hp pull start - my shoulder is still hurting after messing around with my Lark III 40hp a few weeks ago. Several hours of tinkering and trying to start it isn't good for you!

Re: 1965 Evinrude Big Twin 40HP (40502A or 3A)

Haha,

Sounds like hard business to get it to start with the pull starter. I was also wondering why they bothered to do a manual start engine with tiller control. Doesn't seem to be a big seller unless you like pumping up before you go out to to sea

Ok. So compression test is really the only thing needed. What kind of compression figures should I look for except a maximum of 10% difference on each cylinder?

// Mike

Re: 1965 Evinrude Big Twin 40HP (40502A or 3A)

120 psi would be excellent on each cylinder...but could be lower. And even a low psi motor can be increased with running and a de-carb to remove built up carbon and loosen stuck rings.

If the motor looks look and there's good "bounce" in the recoil, I would pull the trigger for $60.

Also, with a pull start, you don't need a battery!

Mas

Re: 1965 Evinrude Big Twin 40HP (40502A or 3A)

Mas said:

Also, with a pull start, you don't need a battery!

Mas

Click to expand...

True! But a lot of muscles ... Thanks, I'll bring my outboard mount and try to meassure the compression. Is it sufficient to remove one spark plug. Pull 2-3 times as hard as I can? I have never messured compression earlier.

// Mike

Re: 1965 Evinrude Big Twin 40HP (40502A or 3A)

Remove both plugs and ground plug wires. Removing both plugs will make it a little easier to pull. Pull about six times. You'll probably not see the numbers you would by cranking an electric start - A good figure with pull starting would be about 90-100psi. in my experience. And of course, even between the cylinders.

Re: 1965 Evinrude Big Twin 40HP (40502A or 3A)

Those motors will start relatively easy with a good ignition stystem in them, but a sarter set up would be worth your investment. I actully bought three motors of this class last weekend LOL I actully can pull start one and got one fired up on the third or fourth pull, but use both hands to lessen the strain.

Like Gas Giant, I too have a Lark III (a glorified Big Twin) which I will start this weekend. 120 psi per cylinder would be nice on one of these but you want at least 90. My '58 Lark I actually puts out 130 per hole but thats a motor with three ring pistons and compression releases.

$60 is a nice deal. Check the ignition out and the gearcase oil too. These two eareas will probably need help.

Re: 1965 Evinrude Big Twin 40HP (40502A or 3A)

Crap!

Thanks for all your input guys! This forum is a goldmine of valuable information. Unfortunately the seller sold the engine to another guy (arrghhhh..). Well - lesson learned. If you snooze, you loose

// Mike

Re: 1965 Evinrude Big Twin 40HP (40502A or 3A)

Well, don't worry. Those 40hp Big Twins are still really common motors and there are train loads of them out there. I'm willing to bet that if you post a want ad here, someone will be willing to let you provide a good home to one of theirs and there is a lot less likely chance that you'll get scammed. There's a lot of good helpful guys here to help out and some have motors that need new homes. Don't give up.