1974 mercury 1500

[JDRains]

I was given a 71 glastron with a 74 Mercury 1500 last month. Actually rode in the boat the last time it was in the water 21 years ago and it would peg the 45 mph speedometer. The motor itself was a fresh rebuild.
I've had to clean 21 years of dirt, dust and varmits even though the boat was in covered storage and rewired it. I cleaned all of the motor wire harness connections, pulled the coil wire to the distributor and cleaned the coil end, pulled the distributor cap off the trigger and lightly cleaned the rotor and the contact points in the cap. New trigger timing belt was installed. Pulled plugs to discover they were brand new, liberally fogged each cyclinder with penetrating oil and let sit for a couple of days before turning over with a battery. I mixed super unleaded @ 50:1 added a half can of Seafoam and some marine stabil. After sitting 21 years it actually fired up and ran after heavy pumping on the priming bulb. I noticed no water coming out of the pee hole so I shut it off.
Definitely going to have all the seals in he lower unit replaced as well as the water pump and pump housing. Before starting it up again. So far it hasn't ran long enough to get warm. I suspect maybe dirt dobbers have got in the lower unit ss to the reason for no water out of the pee hole.
Right now it's a toss up as to whether I have the carburetors rebuilt with lower unit or wait until I can actually run it waith confimed water flow.. Oh, I did swap out 22 prop to a 20.
I welcome any suggestions on what I can expect out of this resurrected old Tower of Power.

 

[jimmbo]

Welcome to iboats
Your engine 99.8 cubic inch displacement
WOT range 4800 - 5800 rpm
2:1 gear ratio
fuel mix 50:1 with a good TCW-3 oil

Here is link with some helpful hints
http://forums.iboats.com/forum/engi...231-awakening-a-sleeping-outboard-by-boatbuoy

 

[1960 Starflite]

I suspect the water pump impeller is in several pieces.

 

[JDRains]

Ok,
The lower until has been completely seviced including water pump and housing. The carburetors have been completely rebuilt ( certified marine mechanic). Timing is good. The motor sounds awsome idling on the muffs. The motor starts with a bump of the key everytime.
The bad---idled out of the no wake zone and gave it some throttle and instantly planed out, let off the throttle to adjust trim ( started porposing ) came back on with throttle and had a noticeable loss of power and sounded as if missing. Tried a couple of more times to plane out but issue remained. I put the boat back on tne trailer and drove 2 blocks to the house.
Scratced my head for a minute and decided to pull the plugs. Found carbon completely fused on the electrod cycl plug 2.
Tried the lake again, boat planed out instantly and sped up but started missing again. Pulled plugs one at a time and discovered carbon fouling on 3 plugs, cleaned and replaced with same results. I've started out with a new gas can, 50:1 mix with 1/3 of a can of seafoam with 6 gallons of 97 oct super unleaded. It seems to drink alot of fuel. The carb mixture screws are set at 1 and 1/ 2 turns out from lightly seated. Question posed is , is this a carbon issue that wiil clear up with proper de-carbon service.

 

[Faztbullet]

Make sure it carbon and not aluminum throw off .....

 

[jimmbo]

1 1/2 turns out from seated is an initial starting point for the mixture needles, final setting is done under load in gear. As for the carbon fouling... which 3 cylinders? What kind of oil are you using? The engine may have been heavily fogged before it was stored so it might be a combo of fogging oil, penetrating oil, and seafoam(which also is mainly a light oil) burning off. Other things could be fuel level is too high causing a rich condition. Do the carbs leak gas when you squeeze the primer bulb when the engine is off? If so then the floats are not set correctly, or the inlet needle is not closing. A proper decarb would require a Combustion Chamber Cleaner or Engine Tuner. I know a lot of people swear by Seafoam, I swear at it and feel there are better cleaners out there. The high octane gas does not offer any advantage, and in fact burns slower and with less power than a lower octane gas

 

[JDRains]

Explain aluminum throw off?

I'm using a penzoil TCW-3 oil, clinders 2,3 and 4 had the carbon issue the 2nd time I took it out. The motor was a fresh rebuild and ran about 3 years prior to sitting up ( belonged to my Uncle ). Don't believe he ever fogged. I found 12 qt. Bottles of 21 year old Quick Silver oil under the seat on the boat. As mentioned this boat has set for 21 years prior to me trying to bring it back to life. I'm listening to all suggestions. This ran fantastic prior to setting up.

 

[jimmbo]

Explain aluminum throw off?.

Aluminum from the piston/cylinder head being deposited on the spark plug. Can occur if engine has experienced detonation, ring breakage, piston scuffing.

Did the carbon on the plug wipe off relatively easily? Soft and mushy, or hard like granite? The deposits might be just the extra additives in the fuel used to raise the octane. Another reason not to use high octane fuel in engines that don't need them

 

[Watermann]

Did you run a compression check on all the cylinders? That should be done before any money is spent on a motor.

 

[JDRains]

Ok, I have completed a thorough job of removing all carbon build up using ( Dunk ) method of 3/4 gal of gas 1 can of Seafoam and 3.8 oz. Oil. Compression is even on all 6 cyl. @ 120 psi. I put the boat in the lake and idled noticeably better. Outside the no wake zone things have warmed up and notice rough idling. Give it gas and acts like its missing and will not plane , no power. The carbs are still at 1 and 1/2 turns out. I tried leaning it out and richening no diffrence. I have an electric fuel pump (72gal per hr @ 8 psi per inch ) with a regulator that adjusts from 0.5 to 8 psi. Set at 2 psi, still no change. Link and sink set at 5 and 20. The front panel inside the cowling as a sticker 23 BTDC. I'm about ready to stop dropping cash and try to recoupe what I've go invested so far.
This boat ran like a raped ape before it set for 21 years would like to see her scream again. Any thoughts?

 

[JDRains]

Forgot to mention replace old NGK BUHW spark plugs with a new set of same plugs.

 

[Watermann]

Your 1974 TOP has a distributor and I haven't seen that you pulled the cap to inspect it. Hows the wiring look, harness, stator and such?

I completely re-wired my 79 with the ADI and replaced everything electrical as your 1500 mine had sat for untold years. I also replaced everything fuel related as well, no sense in rebuilding a carb and hooking up rotten old hose to it that will flake off and plug up the main jets.

 

[JDRains]

New fuel lines, fuel tank, fuel filter and fuel pump before it was ever started after the carb rebuild.
All has been listed but will post again.
New trigger belt - Fresh Carb rebuild by reputable marnie mechanic - lower unit, new seals, water pump housing and impeller, Link -n- Sink @ 20 BTDC. - prop is a 20. De-Carboned cyl. - compression 120 all cylinders. New NGK BUHW plugs same as old plugs. Please look at previous posts to help with suggestions.

 

[JDRains]

Wiring is in good condition , plug wires are good.

 

[JDRains]

Any thoughts on the sticker for 23 degree BTDC?

 

[Watermann]

Try posting in the FB Inline 6 only closed group. There's a bunch of guys there that live and breathe these motors. There's not that many of us here that actively use these IL6 TOP motors who are active in the forum. Mine is the ADI version so I don't know everything there is about the older distributor models. Mine did the same thing as yours though before I replaced all the electronic including the switch boxes.

https://www.facebook.com/groups/213725501742/

 

[Chris1956]

Stick with idle pickup timing of 4-6* BTDC and 21* BTDC for max spark advance. Normally when an inline wont accelerate, the carbs are too lean.

You did set the idle pickup timing when the carbs are still closed, but ready to open, right?

Depending on what boat you have, the 20Pitch prop may be too tall. Those motors build power as the revs increase. If the prop is too tall, the motor will not make enough power to accelerate.

 

[JDRains]

Ok,
Problem solved, found the trigger puley arrow pointing to the right of the crank when set at zero. I can't belive the shop had this running. Aligned to the crank at zero degree and set adjustments at 5 and 20 degrees with timing light. Took the boat out this morning it idled like a totally different motor, hit the throttle and it jumped up and planed out. At 3k on the tac the boat is running 30 mph punch the gas all the way and can definately feel it accelerate. Got a 20 prop on it and it is topping out at 41 mph at 4200 on the tac. The boat is a 16 ft glastron. I have a 100% confidence on all the timing settings. Need to play around with props to see if I can get it up to 5800 rpm. Lesson learned here is, if a mechanic grumbles about working on your boat stop and seek another. I've learned enough working on this motor myself I probably won't be taking it back to another.
Any suggestions on a prop pitch for a 16 ft with this merc 1500?

 

[jimmbo]

Any suggestions on a prop pitch for a 16 ft with this merc 1500?

Normally I would say a 19 or a 17. However if your tach is accurate, that's not going to increase the rpms anywhere close to 5800. Then again, the inline 6 150hp usually wakes up and pulls real hard from 4000 - 6000 rpm, so I would consider trying a 17 and see what happens. Your timing is 3 degrees retarded, that will have some affect on peak power. I know Chris said to keep at 21 as it is less prone to detonation

 

[Watermann]

Glad you figured this one out, those guys shouldn't work on a boat motor they don't like or know how to repair.

I have 17 and a 19p for my 18' with 140 and get 5800 with the 17(41mph) and 5500 with the 19p (45mph). It's all about trim, I can trim until the prop starts to blow out with my boat so what I do is run her up on a plane and start trimming as I ease the throttle forward until wot and then trim until the rpm's are up where I want them.

Yeah my boats hull is not built for speed and is much heavier than your boat but to get the motor at the desired RPMs trimming is key and will be the same on yours. You can not lug these motors down without consequences sooner or later. Your 150 should turn that 20p just fine on a 16'r with the proper trim, if too tall pitch then you'd know it on the hole shot and there wouldn't be the feeling of acceleration like you have.

Tach must be accurate too!