sorrento90
Recruit
- Joined
- Aug 1, 2011
- Messages
- 1
hi to all readers, new to the forum , looking for that expert opinion
in june this year,we bought a 1990 searay sorrento with a 5.7 260 hp merc, less than 350 hours, the engine misfired at the moment we bought it, it still seemed like a great deal.
rebuilt both heads,generally, they were pretty good before the tear down, did a leakdown, now all 8 cylinders leak less than 8%
previous owner had a new cap, rotor, coil picup installed, not sure about the wires, plugs were new,
after rebuilding heads, still had misfire-backfire, installed another new cap-rotor, ran in driveway great for 10 minutes, started to mis fire,
bent the rotor flap upward, ran great for 1 hour, then misfires,
installed another Echlin cap-rotor, ran great on the lake for 2 hours, idle to WOT, then the misfire was back,
so,,asking about the coil, and the timing,
when we rebuilt the heads, distributor was out, as was the battery removed,
we have the thunderbolt IV ignition, we did not short the pickup backside of the coil
just asembled everything, and timed at 8' BTDC
without the evident misfire, one would say everthing went very well,
so, is our timing off so far, due to electronic advance that we cross or pre-fire other cylinders? only back fires to exhaust side,
the coil, showing no identification of an external resistor being required, does the 1990 merc 5.7 (not the magnum series, regular 5.7-260 hp) use an external resistor? i measured 13.7 VDC on the + and 12. something on the negative side.while running after 1 hour,
how hot should this coil be getting, burn hand,,very warm,,cool, based on an 80' f day
would a bench test of this coil determine if the windings have faulted, i have some data on the ohms for primary and secondary, or please post any data you have for resistance values
bought the boat with 3/4 tank of gas,,could be last years gas,,not sure what quality it was,,yet,,with a new cap,,life is great,
i will verify for ignition, and shift switch faults, and loss of continuity,
and loss of voltage at the coil primary side,
not frustrated yet,,but eager to learn,,thanks for any comments,
in june this year,we bought a 1990 searay sorrento with a 5.7 260 hp merc, less than 350 hours, the engine misfired at the moment we bought it, it still seemed like a great deal.
rebuilt both heads,generally, they were pretty good before the tear down, did a leakdown, now all 8 cylinders leak less than 8%
previous owner had a new cap, rotor, coil picup installed, not sure about the wires, plugs were new,
after rebuilding heads, still had misfire-backfire, installed another new cap-rotor, ran in driveway great for 10 minutes, started to mis fire,
bent the rotor flap upward, ran great for 1 hour, then misfires,
installed another Echlin cap-rotor, ran great on the lake for 2 hours, idle to WOT, then the misfire was back,
so,,asking about the coil, and the timing,
when we rebuilt the heads, distributor was out, as was the battery removed,
we have the thunderbolt IV ignition, we did not short the pickup backside of the coil
just asembled everything, and timed at 8' BTDC
without the evident misfire, one would say everthing went very well,
so, is our timing off so far, due to electronic advance that we cross or pre-fire other cylinders? only back fires to exhaust side,
the coil, showing no identification of an external resistor being required, does the 1990 merc 5.7 (not the magnum series, regular 5.7-260 hp) use an external resistor? i measured 13.7 VDC on the + and 12. something on the negative side.while running after 1 hour,
how hot should this coil be getting, burn hand,,very warm,,cool, based on an 80' f day
would a bench test of this coil determine if the windings have faulted, i have some data on the ohms for primary and secondary, or please post any data you have for resistance values
bought the boat with 3/4 tank of gas,,could be last years gas,,not sure what quality it was,,yet,,with a new cap,,life is great,
i will verify for ignition, and shift switch faults, and loss of continuity,
and loss of voltage at the coil primary side,
not frustrated yet,,but eager to learn,,thanks for any comments,