Mercury 500 Long Electric

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Rapier
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Mercury 500 Long Electric

Post by Rapier »

Collected this today. It came with 2 tanks, a 6 gallon (full of fresh fuel) and a 3 gallon steel set, a set of matched remotes and 11ft cables (missing the back..and a quadrant), the cobrahead loom, an 'operators' manual (eaten by silverfish in the middle) and a fresh impeller. It's a freshwater 44 cu.in motor from 1979, probably supplied by Lewis Marine. This model benefits from carbs with individual fuel pumps and ADI ignition, no distributer involved, so space under that side of the cowl , which helps when fiddling with the cable setup. No doubt there were more engineering tweaks between my '69 500 shorty and this, but it's a good model to own and I've always been a bit green-eyed of the 80s longshafts I see on some CMBA members Mini Clubmans. When I thought of a post for this, it was going into the powerplant area, until I realised it was 38 years old and has it's history in the 1962 500 and smaller cube predecessors. It does have issues with running properly, I think related to fuel flow, and some paint loss (not pitting) and a bent and partially broken skeg. Under the covers it's mint, so it'll be a good match for the Arrow V130, which has a long-shaft transom.

As an aside, it's nice to see unmolested motors on an auction site, at reasonable prices instead of overpriced rubbish (of the buyer beware variety). Unfortunately, it's possible for a seller to make more money touting the '99p sparkplug' breaker than an honest cheap, get-one's-hands-dirty project too; so us hobbyists are caught inbetween.
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Alacrity
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Re: Mercury 500 Long Electric

Post by Alacrity »

Nice find!
Mercs are like women, no 2 are exactly alike. That's what testing is about. In general it is safer to test motors and props than women!

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Re: Mercury 500 Long Electric

Post by Rapier »

Yes, not easy to find here these days. Plenty of nice examples in Europe though.

Hoping this is not an indicator of the baboon spanner squad getting there before me..
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Re: Mercury 500 Long Electric

Post by Rapier »

Compressions were fairly even across all 4 cylinders, so I knew that this was to be a viable project. Having ordered a OEM diaphram / gasket kit and found no definitive source in various factory / service manuals as to the type of diaphram to use for the check valves (one rubber, one mesh), I had to resort to checking a dealer's parts bin for the same type of integral fuel pump. This showed the same mesh-like diaphram as those had come off the pumps originally. Brass parts of the carb needed soaking, including both idle restrictions that were completely blocked and had been missed in the past. The carb still smelt of ancient fuel and had tide marks in both float bowls even though someone had cleaned them before. The sellers other comment was that the impeller had been replaced (37 years ago perhaps). It was only a matter of time before 2 of the vanes gave way and caused more problems. The motor had also been run without water, the pump housing showing signs of heat transference and rubber melded to the sides of it - this only takes seconds, so is a no-no. While re-assembling all the wiring I was surprise to have the choke wire crumble in my hand. Mercury wiring is notoriously bad, is no surprise to have the insulation fall off, but the copper core was rotted too.

When all was assembled (with new fuel lines), the motor fired right up - at a later stage I'll warm it up properly, put it under load and get some power tune down it, recheck the compressions and set the carbs properly (past the 1 1/4 idle initial setting). Bar some paint on the l/u and fresh gear oil and washers for the gearbox, it is ready to be mounted on the boat.
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Re: Mercury 500 Long Electric

Post by Rapier »

This formed part of my wiring woes weekend...Is a common Merc ailment. In this case the insulation was shot, in the case of the 300 I have, the wires just crumble to dust.
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Re: Mercury 500 Long Electric

Post by Alacrity »

Amazing really, Mercury back then was the market leader - with prices to match. Yet the quality of their cables is very poor &, as you say,do not stand the test of time - even here in the UK. The yanks suffer much more with more extreme weather conditions.
Mercs are like women, no 2 are exactly alike. That's what testing is about. In general it is safer to test motors and props than women!

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Re: Mercury 500 Long Electric

Post by Rapier »

Alacrity wrote:Amazing really, Mercury back then was the market leader - with prices to match. Yet the quality of their cables is very poor &, as you say,do not stand the test of time - even here in the UK. The yanks suffer much more with more extreme weather conditions.
Definitely had better luck with both the OMC and Chrysler motors (looms..) that I've worked on. There seems to be a rhyme and reason on motors that I've owned that have been sparingly used; the 71 400 and this 500..been a long time since I looked at the '69 500 because that came here in a similar cosmetic condition.

I've cut the loom back to expose better wiring and insulation, so now have to solder the switch back on.
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