New to posting but the info posted here has been my goto knowledge base for yrs.
Boat : 1991 JC Tritoon 26' Drive platform
Inboard/Stern Drive
Engine: MCM 5.7 Mercruiser Thunderbolt IV 4 Barrel Rochester
Engine Serial: 0D622206
Stern Drive: Alpha One
Transom Serial: 0D642254
Total Hours: 390. FRESH WATER ONLY
Dry storage 7 years
Boat was professionally Winterized before a long storage. Boat has only used Premium Ethonal Free gasoline.
The boat is a friends that I agreed to help with it. He had never done a basic tune up since it was new. So as you can imagine it needed it. Boat was missing and lossing power.
Fuel system was gone thru. Checked pressure. Changed Fuel water separator filter and the carb fuel inlet port filter. Fuel was purged and all fresh fuel.
Oil and filter was changed.
Spark aresstor replaced.
Checking the spark plug wires from the dist while running found what appears to be a bad spark plug. Wow what a suprise for 18 yr ignition system parts even if its only 350 hours.. While pulling each wire one at a time I was getting shocked on many just touching them. Again not too suprising wire insulation is cracked at jacket on some.
Replaced Distributor cap and rotor. Rotor was siezed on and had to be broken off. Cleaned up with emery cloth and greased prior to rotor install.
Have a new full wire set that is going on as I do the plugs.
Went to replace spark plugs. I now know why you see no newer pontoon boats with inboards. Outboard only is all you see. What a royal @/#&$!!. The engine is completely recess mounted into the well with no side access ports. The top of the carb is 5" below the top of the well. Maybe 3" clearance from the outside edge of the manifolds to box side wall. But I THINK I can get at them by pulling the 90 degree hose fittings on the pipes. So far I pulled the right side looking at it from the stren drive flywheel end. Combo of thinwall socket 360 flex adapter and hinge jointed socket wrench I think will get them.
I managed to pull the first one before I lost light. I guess that is number 8 cyl as its the closet one there on the right side with 1 being left side far end.
I had picked up NGK-BR6FS which equal the standard AC43T. But I got a suprise when I pulled the plug. It was a NGK-UR4 which of course is a resistor plug with ext tip and cross ref with the newer vortec engine ver of the 5.7 plugs. There is no question these are the plugs that came on this engine new from the boat manf. They also have the extended tip. I had always thought using these would or could create a clearance issue?
I then think I figured out why they may have been used. The longer body puts the nut face for the socket farther out which allows a easier fit of sockets to get past the manifold at that angle. I noticed I could not get the standard 43t/br6fs with the socket without further grinding the socket as it has to go further into the clearance area. This is something I have never seenbmentioned. The socket nut surface is further extended on the resistor ext tip plugs and more recessed on the standard plugs. At least in my situation it makes them easier to get a socket on becuase of manifold design. Anyways just an observation.
My other thought and its just a swag is if an extended tip does clear the piston it should give a cleaner combustion and a longer life to the plug. Nothing to write home about but at least in theory is should??
Any ideas or helpful hints for getting to the other plugs short of pulling the manifolds?
Anything else I should be looking to replace? The stern has been fully serviced and has fresh grease impeller etc
I replaced the tank anti-siphon valve fitting and the float/sending unit as the latter was not working .
One great upgrade he got it wiyh that everyone that sees iy loves is the upper drive plaform. But it has to add serious weight but man do people love using it for jumping and sunbathing. Basiclly adds 50% deck space to an already good size pontoon.
Boat : 1991 JC Tritoon 26' Drive platform
Inboard/Stern Drive
Engine: MCM 5.7 Mercruiser Thunderbolt IV 4 Barrel Rochester
Engine Serial: 0D622206
Stern Drive: Alpha One
Transom Serial: 0D642254
Total Hours: 390. FRESH WATER ONLY
Dry storage 7 years
Boat was professionally Winterized before a long storage. Boat has only used Premium Ethonal Free gasoline.
The boat is a friends that I agreed to help with it. He had never done a basic tune up since it was new. So as you can imagine it needed it. Boat was missing and lossing power.
Fuel system was gone thru. Checked pressure. Changed Fuel water separator filter and the carb fuel inlet port filter. Fuel was purged and all fresh fuel.
Oil and filter was changed.
Spark aresstor replaced.
Checking the spark plug wires from the dist while running found what appears to be a bad spark plug. Wow what a suprise for 18 yr ignition system parts even if its only 350 hours.. While pulling each wire one at a time I was getting shocked on many just touching them. Again not too suprising wire insulation is cracked at jacket on some.
Replaced Distributor cap and rotor. Rotor was siezed on and had to be broken off. Cleaned up with emery cloth and greased prior to rotor install.
Have a new full wire set that is going on as I do the plugs.
Went to replace spark plugs. I now know why you see no newer pontoon boats with inboards. Outboard only is all you see. What a royal @/#&$!!. The engine is completely recess mounted into the well with no side access ports. The top of the carb is 5" below the top of the well. Maybe 3" clearance from the outside edge of the manifolds to box side wall. But I THINK I can get at them by pulling the 90 degree hose fittings on the pipes. So far I pulled the right side looking at it from the stren drive flywheel end. Combo of thinwall socket 360 flex adapter and hinge jointed socket wrench I think will get them.
I managed to pull the first one before I lost light. I guess that is number 8 cyl as its the closet one there on the right side with 1 being left side far end.
I had picked up NGK-BR6FS which equal the standard AC43T. But I got a suprise when I pulled the plug. It was a NGK-UR4 which of course is a resistor plug with ext tip and cross ref with the newer vortec engine ver of the 5.7 plugs. There is no question these are the plugs that came on this engine new from the boat manf. They also have the extended tip. I had always thought using these would or could create a clearance issue?
I then think I figured out why they may have been used. The longer body puts the nut face for the socket farther out which allows a easier fit of sockets to get past the manifold at that angle. I noticed I could not get the standard 43t/br6fs with the socket without further grinding the socket as it has to go further into the clearance area. This is something I have never seenbmentioned. The socket nut surface is further extended on the resistor ext tip plugs and more recessed on the standard plugs. At least in my situation it makes them easier to get a socket on becuase of manifold design. Anyways just an observation.
My other thought and its just a swag is if an extended tip does clear the piston it should give a cleaner combustion and a longer life to the plug. Nothing to write home about but at least in theory is should??
Any ideas or helpful hints for getting to the other plugs short of pulling the manifolds?
Anything else I should be looking to replace? The stern has been fully serviced and has fresh grease impeller etc
I replaced the tank anti-siphon valve fitting and the float/sending unit as the latter was not working .
One great upgrade he got it wiyh that everyone that sees iy loves is the upper drive plaform. But it has to add serious weight but man do people love using it for jumping and sunbathing. Basiclly adds 50% deck space to an already good size pontoon.