15HP 1956 Evinrude

[GMCAMARO]

Went fishing yesterday, motor was running wonderfully. Stopped several times, after the second to last stop the motor started back firing through the exhaust and then all the way home motor backfired. Typically this was at low idle or mid throttle. I took the spark plugs out, one was black with carbon, the other was perfect.<br /><br /><br />I cleaned them up and put them into the other hole, but the problem remained, any ideas?

 

[rickdb1boat]

Re: 15HP 1956 Evinrude

First thing I would check out is the points, as they directly affect your timing. They should be clean(Not pitted or dirty) and set at .020. Also you might replace the condersor while you're at it and see if that helps. Compression check would be a good idea, too.

 

[GMCAMARO]

Re: 15HP 1956 Evinrude

How much trouble is getting the fly wheel off?

 

[rickdb1boat]

Re: 15HP 1956 Evinrude

Not too much if you have the correct flywheel puller... You should be able to get a Harmonic Balancer puller from an auto parts store that will work..

 

[grizzlyadams]

Re: 15HP 1956 Evinrude

couple of quick blows from a hammer on the bottom edge usually works

 

[Chinewalker]

Re: 15HP 1956 Evinrude

DO NOT strike the flywheel with a hammer!! It is cast aluminum and can be thrown out of balance quite easily! Get the right puller (they're not expensive) and do it the right way. You'll need to get three cap screws in 1/4"-20 size, long enough to for the puller. Most pullers don't come with the 1/4"-20 bolts...<br />- Scott

 

[SCO]

Re: 15HP 1956 Evinrude

do you have to take off the flywheel to check the points? On my 58 there are ports in the flywheel for checking points and setting timing.

 

[GMCAMARO]

Re: 15HP 1956 Evinrude

I took the whole thing to someone today to get their opinion. They quickly changed the plugs and richened the whole thing up. Runs great again. Was a bit surprised, because it was running great, so why did the low speed mixture change? Got me. He checked the compression and found it was fine in both cylinders. Any thoughts as to why one cylinder would be great and the other plug carboned?

 

[Chinewalker]

Re: 15HP 1956 Evinrude

The needles on those motors are prone to moving on their own if the packing nut isn't tight enough or of the packing has been removed/deteriorated. At the base of both needles (high and low speed) there is a brass nut. This nut compresses the packing material (a fiber washer) against the shaft of the needle to give friction to the shaft. You might be able to tighten the nuts up just a bit and see if the needle turns less easily.<br /> If the packing is shot and you can't find the packing material you can use cotton thread, wrapped around the shaft, with a dab of motor grease to keep it wrapped. The packing nut should not be able to slide over the packing material - just enough to go in the hole in the carb, but not enough to block it. <br /> Great old motors and well worth a little TLC to keep going...<br />- Scott

 

[GMCAMARO]

Re: 15HP 1956 Evinrude

I actually replaced the packing nuts this winter and this morning tightened them up just a bit.