The Online Magazine For Amateur Boat Builders

Obsolete Outboards
by Max Wawrzyniak

Start to Finish, Book II:
(Part 1 - Part 2 - Part 3)

Reviving a Vintage Big Twin
Part 4 - Conclusion

The Big Twin's initial test run can be called a success; the engine started easily and ran well. It was obviously too much horsepower for the AF4, even with it's under-sized propeller. Although I did not hook-up the tachometer, it seemed pretty obvious that the engine could use a propeller with more more pitch, which should increase the speed a bit.

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(click images to enlarge)

I ran the engine with the tiller , and then coupled the AF4's remote controls up to it, which only took a few minutes (one of the reasons that I recommend these old OMCs). As I mentioned way back in the column concerning remote throttle and shift controls, there is a friction disk underneath the throttle twist-grip throttle that needs to be removed when remote controls are used with these engines so as to avoid excessive loads on the controls. I was unable to loosen the screw retaining the twist grip with a screwdriver so decided to limit my test running and work on the twist grip back at the shop, where my handy and cheap impact driver (mentioned in the recoil starter column) would make short work of the reluctant screw.

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Speaking of recoil starters, I will most likely replace the rope on the Big Twin, and maybe the spring as well. It is just so much better to do it at home than to have to deal with a broken rope or spring on the water, possibly ruining a too-infrequent day of boating.

Last Friday, while at work, I recieved a cell phone call from a manager who I knew to be on vacation. My curiosity as to why he would "call-in" on a vacation day was quickly satisfied when he asked for the oil-mixing ratio for a late-model Mercury 9.8 hp outboard.

About an hour later he called again. Now he was sitting in the boat holding the broken end of the starter cord and wondering what to do next.

How do you think his vacation day went?

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Would having replaced a 50-cent piece of rope in advance made an improvement?

A big part of the reason that the Big Twin, like the 5 1/2 featured in the first "Start to Finish' series, was easily and cheaply "revived" involves the selection of the engine; I feel it is best to avoid engines showing signs of abuse, which includes make-shift repairs. Both of the "Start to Finish" engines had all their knobs and screws and parts, and neither had signs of slip-shod repairs. They had few screw heads with
stripped slots and no missing screws,

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They had been ignored but not neglected. That both engines still had cracked coils indicated that they had seen little use, and no use in recent years, as it did not take too many years for these coils to start cracking.

Do not mistake a poorly-appearing engine for one that has been abused, however. A really poor repaint job might hide a very sound engine.

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I again will suggest that a "cheap-power" seeker begin his outboard education by attending some of the swap meets sponsored by the Antigue Outboard Motor Club; their swap meet schedule is posted online:

These meets are an ideal way to learn about old outboards and how to evaluate them. You will always find people there who are ready, willing, and able to talk about old outbaords just as much as you care to listen too.

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Beyond the swap meets, I feel it is also a better idea to purchase engines from private parties looking to rid their garage / basement / storage shed of what they consider a nuisance, rather than to deal with people who are trying to make their living off of old engines. You are doing the former a favor by hauling-off something that he might otherwise have to pay to get rid of. Substitute his gratitude for your cash.

Back to the Big Twin; once I get around to looking at the recoil starter, I will consider it to be a "runner," and other than normal maintainance and winterization, it should require little more "wrenching"

Happy Motor'n