Merc 1100 Tower of Power Restoration

[DOUGLAS G. ROBERTSON]

I have a 1966 Merc 1100EL-SS that I am planning to restore.   I don’t have any history about the motor, but it was complete when I bought it.  It appears to be a freshwater motor.  I have previously restored a 1966 Merc 500 so I understand the basics.  I plan to replace the fuel hoses, wiring, water pump, plug wires, rectifier, rebuild the carbs, rebuild the fuel pumps and whatever else it needs.  I have the factory shop manual and the factory parts catalog.

Here are my questions:

1.  What spark plugs should I use?  It originally had polar gap plugs, but it came to me with L77J4 plugs.
2.  Should I use the original electronic ignition components if they still work?  The distributor is in good condition.  My motor has the rectangular coil with one spark plug wire.  Are there any options for a more modern ignition system?  Didn’t the earlier Tower of Power have points?
3.  The lead tamper seal on the crankcase halves is missing.  There is a bit of sealant that has oozed out from between the halves, so I suspect someone has opened the crankcase.  The block shows no signs of overheating.    I haven’t tested compression with a gauge, but it has compression when turning by hand.  Assuming it passes the compression test, should I open up the block or try it like it is?
4. Can I replace the crankshaft seals without removing the crankshaft from the block?
5. Can the lower unit seals be replaced without disassembling the lower unit?
6. What else should I look out for?
7. Any tips on repainting?

Any advice is appreciated.

I have boat towing service from BoatUS, and I operate on an inland lake, so an engine failure isn’t a disaster.

Thanks,

Volts

[jeff-register]

One item I would do is on top of the cylinder block is a water passage 1/4″ plug. Put a 90 degree brass fitting & tubing down to the bottom cowl so you can always see water flow to the top cylinder. Your book should show the correct plugs to use. & yes the early 6’s had two automotive coils & the distributer was different. The cap  had 2 places for coil wires & dual contacts on the rotor. One coil ran 1,3 & 5cylinders & the other ran 2, 4 & 6 cylinders. The points  2 of them raan each coil &  must be syncked to each other other wise 1,3 ,5 were firing before or after 2,4 & 6 cylinders. The reason for dual system is there wasn’t time between cylinder firing to saturate the coils for a hot spark at 6000 rpm. Be careful if you split the cases, They have a bad habit of breaking bolts off. See Joe Poole  for parts at Ferguson Poole on the web. His Dad started the business in 1951 & has many new old stock parts. Very nice guy too!!He is on the web. Check the cooling ystem very well + the check valves for crankcase drains to be functioning. Hope you don’t have to open it up. It’s a real trick getting the exhaust system seals not to leak water.P.S. It probally had a piston burned because on of the three carbs ran dry for some reason.It’s harder to tell a dead cylinder when it’s 6 of them. Crankshaft sealsmust be replaced by splittong the crankcase & top main bearing should be replaced. Mercury used surpluss military bearings & seals but hopefully yours is new enough to not have surplus parts in it. They are hard to find now.

Good luck & be patient!!

[dave-bernard]

call me 1 914 310 7086 Dave

[jeff-register]

Doug,

Please call Dave he knows much more than me!

Did you do a compression test yet? What were the results? That model is a good motor. You have a “Thunderbolt” type ignition, very high voltage, be careful & keep very good spark plug wires on it otherwise it will leak & arc to ground,

 

[DOUGLAS G. ROBERTSON]

I did the compression test.  All cylinders are within 10 psi of each other.  The top two look about like the others.  They range from 120-130 psi.  Based on this, I don’t intend to open the crankcase.  I don’t want to kick any sleeping dogs.

I have three broken off bolts on the cylinder head cover.  Two are on the starboard side and I tapped them toward the front of the motor and they came out.  I think I can get the one on the port side by using a Dremel grinder to carefully remove the nut from the shank of the bolt and then push the shank toward the back of the motor and out.

Should I use stainless bolts on the cylinder cover?

I inspected the check valves on the crankcase drains.  They will pass air in both directions.  Shouldn’t they have a check ball in them?  Mine don’t.  Also, the keeper was not bent into the correct position to hold them from rotating.  This looks like results from previous repair work.

The exhaust cover looks good and I can’t see any signs that it was leaking water.  I don’t plan on removing it at this time because I would expect to break bolts trying to get them off.  I’ll see if it leaks when it is running and then decide what to do unless I get different advice from one of you experts.

At this point it is so far, so good.

[DOUGLAS G. ROBERTSON]

I just talked to Dave.  He is an incredible storehouse of knowledge on Mercury.  He was extremely  helpful and gave me a lot of useful advice.

[jeff-register]

Doug,

I know Dave is a great welth of knowledge. On the broken bolts removed I wouldn’t use stainless. They arn’t as strong as grede 8 steel bolts. The cover you speak of is only the water gacket cover, Mercurys have no head. The cylinder & head are cast into one piece. I don’t remember if the crankcase check valves are one way or not. Consult your manual. Oh, Just remembered, If you can find “steam fitting anti seeze” use that on all threads. I have a can  & it comes with a brush about a pint size. We used it at the hospital on all steam fittings & that steam was so hot we called it dry steam for sterolision. Sorry speling! Anyway we could always get the pipe apart & it was under such pressure it would sound like hitting a pipe with a hammer during delivery. A good plumbing supply store should have it. Stick with Dave he has been working on Mercury’s from the 50’s.

Glad you are moving forward, Please give a progress report, you have one of Mercury’s best build!! & glad the compression is great!!! P.S.Yes they should be check valves too. Picture please! I still have my 1957 Mercury 6 cylinder motor. The starter was double wound because it was direct drive, no shift. To get reverse turn off, pull the throttle back & restart the motor reverse rotation. The distributer drive had 180 degree slop so starting in reverse the timing was corrected for running backwards. They were called Dock busters because it took too long to get reverse working. The waterpump worked in either rotation. Fun motors to master! They were so different.

[DOUGLAS G. ROBERTSON]

Progress report:

The electronic ignition box and the coil are functional.  The system produces a 1/4″ spark.  About 3 of the 6 spark plug wires are bad.  They have the threaded fitting that screws into the distributor cap, so I guess I will have to find some N.O.S. wires.  My distributor has points but no condensers.  There are two sets of points.  When wired together per the diagram in the shop manual, they make six pulses per revolution of the distributor.  Dave Bernard said I will have to set the points carefully so that three of the cylinders are not leading the others.  I’m pretty sure I can do this using a degree wheel.

I figured out the mystery with the check valves.  I was looking at the balance tube system.  Once I realized there was another set of fittings into the crankcase it all made sense.  My check valves pass a small amount of air in one direction and none in the other.  As I recall they pass air outward from the crankcase.  They had a lot of black goo inside them, so I ordered new ones from Ferguson Poole.   I don’t know if they have some plastic parts deep inside, so I’m not taking a chance with using solvent at this point since Ferguson Pool can supply them.  Once I get the new ones I can take some chances trying to repair the old ones to have as spares.  Joe Poole, Jr. at Ferguson was very helpful and had everything I needed.   I will probably have to make a second order for the spark plug wires.  Hopefully they will have them.

I attempted to do a pressure test on the gearcase.  I couldn’t get it to hold any pressure at all.  I’m not sure if I had my fittings tight or whether there is a bad leak.  I got called away before I could figure it out.  I’ll probably try the soap bubble test.  I suspect I have a major leak at the propeller shaft seal.  There is a lot of oil around that area, but it could be TCW-3 dripping out.  I plan to reseal the gearcase anyway, but it would be nice to know where the leaks are.  I hope the shafts aren’t all rusted where the seals run on them.

I’m rebuilding the fuel pumps now.  They are all cleaned out and ready for the new  parts.

I removed the cowl support brackets and am getting ready to clean the engine block prior to painting.  I ordered some paint from Peter at NYMarine.

Overall, so far, so good.  I think the gearcase is the last big question mark.  Everything else appears to be repairable.

[jeff-register]

Moving forward!! That’s great. Yes Joe is a personal friend too as well as a great parts sourse. If you go thru the gearcase watch out for tiny shims. They stick to the gears & hard to detect. Do you have the spanner tool for removing the round nut holding the propshaft on? If not Joe will have one or I made my own from hardened pins from the nut & bolt store & a piece of 3/4″ x 2″ steel from a old trailer hitch from a car. There is a very thin bolt holding the pinion gear to the propshaft & requires taking a 6 point box end hand wrench & grinding the bevel off one side to engauge the head of the nut to remove. to get total engaugement on the hex of the bolt & order a new locking tab from Joe. You will need to remove the bent up tabs before removing the bolt. The pinion is on a tapered bore so it still might be tight on the drive shaft after removing the bolt, that is normal. My 1965 & earlyer Mercury manual shows your 1100 but no drawing for your motor. I assume it’s the same as earlyer motors. You will be impressed the first time you go out!! Replace the check valves in the fuel pumps too & look for dirt under them.Did Dave have a way to remove the crankshaft seals without splitting the cases? Some cases start to leak compression & need to be resealed. You can spray soapy water on the mating surfaces while ideling & look for bubbles. We had to reseal the cases on a 80hp 6 cylinder once. Wouldn’t idle & kept running out of gas because of lack of pressure inside the crankcase. Mercurys a known for low fuel pump pressure on 6’s.

Great job & good luck.

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