Stupid Question from New Member

Jemecad

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I recently acquired a 1966 Larson Lapline with a Mercruiser 110 engine. I’ve worked on engines most of my life, but have a stupid question that I need to ask someone - and I’m hoping that you experts might have the answer or know someone who does. The engine was running a bit rough. I found the plugs a little worn and replaced them. I changed the air and fuel filters and checked the carb bowl and jets for debris and everything looked good. The distributor cap and rotor are both corroded so I’d like to replace them (recommended source?). My stupid question is how in the heck does the rotor come off? I can slide it up and down on the shaft, but it doesn’t come off. I don’t see any type of stop screw, retaining pin, keyway or any other type of retention mechanism. After removing everything that looked like it might hold the rotor shaft, I now have a collection of springs, levers and Lord knows what else floating loose below the timing plate that I can’t attempt to reconnect because the plate can’t be removed unless the rotor is removed first. Any tips would be greatly appreciated! Thanks. Joe
 

dubs283

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1966 sterndrive will require pics to properly diagnose the issue

Is the engine/drive painted green or black?
 

nola mike

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I recently acquired a 1966 Larson Lapline with a Mercruiser 110 engine. I’ve worked on engines most of my life, but have a stupid question that I need to ask someone - and I’m hoping that you experts might have the answer or know someone who does. The engine was running a bit rough. I found the plugs a little worn and replaced them. I changed the air and fuel filters and checked the carb bowl and jets for debris and everything looked good. The distributor cap and rotor are both corroded so I’d like to replace them (recommended source?). My stupid question is how in the heck does the rotor come off? I can slide it up and down on the shaft, but it doesn’t come off. I don’t see any type of stop screw, retaining pin, keyway or any other type of retention mechanism. After removing everything that looked like it might hold the rotor shaft, I now have a collection of springs, levers and Lord knows what else floating loose below the timing plate that I can’t attempt to reconnect because the plate can’t be removed unless the rotor is removed first. Any tips would be greatly appreciated! Thanks. Joe
Many times the rotor is glued on, needs to be broken to remove. Dremel, pliers, punch, etc
 

Scott06

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Many times the rotor is glued on, needs to be broken to remove. Dremel, pliers, punch, etc
This - had to chisel mine off.

Engine & drive are both black
Your engine is the 153 ci/2.5 l which is the smaller brother to the current 3.0. The engine family is related to the 194/230/250 ci straight 6, and was first insatlled in the 62 chevy II. Your drive set up is likely the early EZ shift vs the newer MC-1 drive. Merc only made the EZ shift 64-66, wasn't a great design, has tilt only not trim.

Had one of these outdrives on my grandfather '66 Penn Yan, hydraulics never worked right ...
 

dubs283

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Your engine is the 153 ci/2.5 l which is the smaller brother to the current 3.0. The engine family is related to the 194/230/250 ci straight 6, and was first insatlled in the 62 chevy II.

I was thinking this as well. One other thought I had was a renault engine? Dunno when merc stopped using them

A picture or five would help
 

Bondo

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I was thinking this as well. One other thought I had was a renault engine? Dunno when merc stopped using them

A picture or five would help
Ayuh,..... I think they called that motor the 80 hp,....
 

Scott06

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110 hp is the 2.5 Chevy based. Neighbors had one in their StarCraft
 

Jemecad

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Jul 1, 2023
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Thanks for the replies. Since the consensus seems to be to destroy the current one that’s what I’ll do. I would appreciate any suggestions on the best places to source its replacement a purchase a new distributor cap as well.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Your local napa, your local Mercruiser dealer, or even iBoats. However NAPA may have stock, or can get in a day
 

Jemecad

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Okay. There are no makings on the rotor or distributor cap. I haven’t been able to find part numbers on line so far. Any favorite links out there for old boat parts? My engine is a straight four.
 

Fun Times

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Okay. There are no makings on the rotor or distributor cap. I haven’t been able to find part numbers on line so far. Any favorite links out there for old boat parts? My engine is a straight four.
Here's your engine parts catalog for you, https://www.mercruiserparts.com/110-gm-153-i-l4-1963-1966-1537370-thru

Cap and rotor part numbers here, https://www.mercruiserparts.com/bam/subassembly/30877/1552/5

Original rotor part number 33659 SIERRA 18-5418 Rotor, distributor OE REPLACEMENT.
Note item number 19 is a washer, 36275.

And the under-side of the rotor looks like this to maybe help get it off,

1688335342492.png


 

jimmbo

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May 24, 2004
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13,446
Mercury Part #s
Rotor 8M6001251
Cap 393-9459Q1


Sierra
Rotor 18-5418
Cap 18-5385

FT beat me by a few seconds
 

Jemecad

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Jul 1, 2023
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7
All the responses have been very helpful. I need to tap the well once more time. After four hours on the web, I haven’t been able to find a source for ignition specs - point gap, timing and dwell. Can anyone provide another great link or the specs themselves? Thanks again!
 

Fun Times

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All the responses have been very helpful. I need to tap the well once more time. After four hours on the web, I haven’t been able to find a source for ignition specs - point gap, timing and dwell. Can anyone provide another great link or the specs themselves? Thanks again!
You'll need mercruiser service manual number 1 (part number 90-68648) in-which you can buy on the cheap at say Ebay used or find an online place to download for a small fee usually.
Once in a while you can search some out at no cost, but manual number 1 seems a challenge to find one for free on the quick.

 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Going off memory so don't take as gospel

Set dwell to 30-32. Timing is going to be 2-4 BTDC
 
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