OMC Big Twins

The motors about which I am concerned are the 1960's 33 and 40 hp models (mechanical shift), can one of these motors in good condition and maintained, be expected to deliver a reasonable service life, with occasional use in salt water?<br /><br />The 33hp appears not to be a thermostat equipped motor, is there any significance to this?<br /><br />Anyone have spec information on these motors?<br /><br />A lot of questions, any help is very much appreciated, thanks for the great forum.

Re: OMC Big Twins

Welcome to Iboats, R.C.<br /><br />Certainly, if it's in good condition already. Many common service parts for them are still available and still manufactured. Plus they tend to be on the less expensive side, as far as outboard parts go. Iboats, for example, will sell you a new ignition coil for less than $20. <br />I would expect the 33hp to wear out a little faster than the 40hp and be a bit cold-natured since it's missing the thermostat. <br /><br />As for specs, the 40hp were 43.9CID engines, while the 33hp were 40.5CID. The 33hp was based off the late 50's 35hp engine which was the largest twin sold then. There's a few internal updates to it, and externally there are quite a few changes. The WOT ranges for both engines are 4000-5000 RPMS. The 40hps were generally Cadillac engines, often laden with features, while the 33hp engines were 'economy' ones. Period information can be found at the Old OMC Site.<br /> <br />I will warn you, my opinion is biased about these engines. My 28hp (early '60s 35.7CID Big Twin) is sitting behind me, fresh from the painter's. I'm gonna need to get some sunglasses for in here. <br />Many other people here run older big twins too. Some Twin twins.

Re: OMC Big Twins

hello<br /> we ran those old engines while beach fishing for years. keep good fuel, good points and replace the entire water pump every other year and odds are it will out live ya. I still have a few about that I or my cousin have serviced yearly since new. they are tough and durable. most die from neglect. if you ever "need" a water pump there is a good chance you will "need" pistons as well. the object is to fix it long before it breaks and it wil run a long long time.<br />periodically( every third year or so) rebuild the carb and fuel pump as a maint issue.<br />I hve never ever seen one of the 40 or 33 wear out. I have seen a bunch with scorched pistons due to customer neglect. pistons rarely fail bythemselves. usually its due to a cooling system or fuel system failure