1978 Johnson 235 Seahorse Motor

[boat1978]

we just purchased this used boat with this motor. looks to be in great shape. what is the ratio of gas to oil for this particular motor. we started it and it has some black smoke, but not too much. we don't want to ruin the motor.

 

[tashasdaddy]

Re: 1978 Johnson 235 Seahorse Motor

50:1 87 octane : TC-W3 outboard oil. it does not have a tale tell to show the impeller is pumping. it has exhaust port on the upper rear of the leg, you should get drops or mist out of it. from sitting probably needs a decarb.

Decarb, take a can of seafoam put 3/4 of it in the gas tank, with only 1 gallon of premixed gas. put the rest in a spray bottle. start the engine, and let it come up to temperature. then remove plugs, and them some real good shot of seafoam into the cylinders, replace plugs, let sit 15 minutes. restart, and spray the rest of the seafoam into the carbs, so the the motor almost stalls, wait and repeat until the seafoam is gone.then take for a wide open spin. then put in new plugs, ad premixed gas to the tank, and take it for a wide open throttle spin. it is going to smoke like a house on fire, during this process.

afterwards compression.recheck

also read these >>http://forums.iboats.com/showthread.php?t=299680

 

[boat1978]

Re: 1978 Johnson 235 Seahorse Motor

Thanks - we will try this.

 

[emdsapmgr]

Re: 1978 Johnson 235 Seahorse Motor

The factory required octane for this engine was 89 in 1978. The original factory timing was set at 28 and the engine has high compression heads. If the max timing is still set at 28, I wouldn't run anything but premium in it. The 235 that year has a telltale in the lower cowling-plumbed into the outer exhaust cover.