Project Mercury 350

For pre 1975 outboards and race motors only.

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Rapier
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Re: Project Mercury 350

Post by Rapier »

Went back to this yersterday following the purchase of new fuel lines that needed fitting. Mounting a starter motor had put stress on the aged lines and they leaked badly. To fit the starter motor on these you need to drop the lower cowl - I managed to shoe horn it in by filing a bit of the casting without doing so. The solenoid was toast and a NOS replacement was bought cheaply on fleabay. I wasn't able to start it having done the conversion last year, so tried it, but found the motor sluggish and all other cables cleanly connected and new - again the starter motor was a mess and needed to be dismantled, cleaned out and dressed up. Works perfectly, but no1 cylinder is not sparking now, possibly the coil at issue, or points damp/dirty - will pull the flywheel again. At the same time I found a recently seized starter motor in my parts pile and opened that up to it had been used on a saltwater motor; although outwardly good looking it too was a mess inside. Hopefully a proper service will bring it back to life.
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Rapier
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Re: Project Mercury 350

Post by Rapier »

I found a later end cap with damaged brushes, but an intact bush housing - the corroded one had split in half and the set screws were corroded in place - one snapped just when I thought it was ready to come out, so the stud had to be heated out. Swapped the two over, cleaned / washed out the armature, blew it dry and re-assembled the motor and the now cleaned-up end cap, aligning the marks on the motor body. The extra casting end cap is for later motors with a lower casting on the front of the block - is designed to cope with the torque produced and generally has a big nylon bung it sits in. The other wheeze is I don't have the tool one can make up from ali, in order to hold the brushes down while the armature motor slides in from the top, so I use a cable tie to hold down 2 sets while my fingers, or a flat ruler, hold the other 2. Job done and the motor is willing, when bench tested. Remains to be seen if it can take a proper load, but with factory price of £60 for an end cap (NLA) and £300+ for a starter motor, or £114 on fleabay for a generic, it seems a worthwhile job.
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Rapier
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Re: Project Mercury 350

Post by Rapier »

Pulled the flywheel on this one and had a closer look at the points, as the resistance / continuity test on both coils was producing 6.5K Ohms. Re-setting the points to 0.020 produced no spark on 1, so I dismantled the armature plate and pulled both sets of points, which were outwardly fine in terms of resistance, but still dirty and marginally pitted. Dressing them up, cleaning and regreasing the plate and reassembling then produced a fat spark on both. This motor had Champion J8s which are the wrong plug - not a fan of Champion, so swapped both out for new NGK B6S. Torqued the flywheel and assume all will fire up tomorrow.
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Rapier
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Re: Project Mercury 350

Post by Rapier »

Runs well, but tell tale blocked, will take a line off the top of the block from the existing fitting.
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Re: Project Mercury 350

Post by Rapier »

Thanks to a kind CMBA member who explained pipe threads to me, I was able to think through a solution for the bypass that didn't involve buying anything on fleabay. This is a cut down section of the original fuel line from this motor. I'll prepare a few more, as most of these 60s blocks have a blanking plug in this position - this was a freshwater motor so was easy to remove.

The starter motor shown is the original for these motors - it was salvaged off the original lump of corrosion from Healey75, but refused to work under load (blame my ebay cables..). I think it's an early Delco-Remy and the brushes sit either side of the commutator rather than facing upwards in the base. Needlesstosay a quick 'service' and re-assembly and bench test means it can be put into the spares box for later.
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