opalized1
Seaman
- Joined
- Apr 5, 2017
- Messages
- 64
Ok after much ado I finally figured out my engine issues, with low to no power off idle, and incredibly poor performance at WOT
My Engine is the 1967 Mercury Outboard, 950SS Thunderbolt, and after many hours of searching I could not find the firing order for this motor, to include in service manual for this year and engine.
But, on the cap of this era motor is 3 firing orders stamped on the cap.
60 to 66 ci motors, now im guessing this was probably the generic, 550, 650, 750 motors
1,2,5,6,4,3
76ci and larger, engine, again the generic version, 850, 950, and 1100, (it appears through reading, the 1150, 1250, 1350 are different class of motor than lower horse power motors)
1,2,3,4,5,6
The above firing orders, I know are correct, but im not 100% sure which one goes with which class of engines, i.e. 60 to 66 ci engines could be 1,2,3,4,5,6, and 76 ci and larger 1,2,5,6,4,3
all Thunderbolt 6 cylinder engines
1,6,3,2,5,4
My motor was only running on 4 cylinders, 2 and 3 where not firing, but had great spark, so in messing around I swapped cylinder 2 wire to plug 3, and it began firing, so this lead me to break down and pull the cap to look at the stamping, this cap is bolted down with 4 bolts, and not very easy to remove.
Once I switched the wires to the firing order as shown above for thunderbolt, all six cylinders where firing, and very consistant in rpm drop when plug wire was pulled which was part of my issue prior, my compression is exactly the same all six cylinders, give or take one lb, and when I pulled the wires from the different cylinders my rpm drop was as much as 30 rpms different, telling me something was majorly wrong, I had expected rpm drop per cylinder to be within 5 rpms if all cylinders have same compression.
So this weekend my boat hit 32 mph top speed, and throttle linkage is not currently quite getting full throttle out of the carbs, and timing at WOT is alittle to much, so with those adjustments made, and a prop more appropriate for the size of boat, I hope to entertain 40 mph when im done
My Engine is the 1967 Mercury Outboard, 950SS Thunderbolt, and after many hours of searching I could not find the firing order for this motor, to include in service manual for this year and engine.
But, on the cap of this era motor is 3 firing orders stamped on the cap.
60 to 66 ci motors, now im guessing this was probably the generic, 550, 650, 750 motors
1,2,5,6,4,3
76ci and larger, engine, again the generic version, 850, 950, and 1100, (it appears through reading, the 1150, 1250, 1350 are different class of motor than lower horse power motors)
1,2,3,4,5,6
The above firing orders, I know are correct, but im not 100% sure which one goes with which class of engines, i.e. 60 to 66 ci engines could be 1,2,3,4,5,6, and 76 ci and larger 1,2,5,6,4,3
all Thunderbolt 6 cylinder engines
1,6,3,2,5,4
My motor was only running on 4 cylinders, 2 and 3 where not firing, but had great spark, so in messing around I swapped cylinder 2 wire to plug 3, and it began firing, so this lead me to break down and pull the cap to look at the stamping, this cap is bolted down with 4 bolts, and not very easy to remove.
Once I switched the wires to the firing order as shown above for thunderbolt, all six cylinders where firing, and very consistant in rpm drop when plug wire was pulled which was part of my issue prior, my compression is exactly the same all six cylinders, give or take one lb, and when I pulled the wires from the different cylinders my rpm drop was as much as 30 rpms different, telling me something was majorly wrong, I had expected rpm drop per cylinder to be within 5 rpms if all cylinders have same compression.
So this weekend my boat hit 32 mph top speed, and throttle linkage is not currently quite getting full throttle out of the carbs, and timing at WOT is alittle to much, so with those adjustments made, and a prop more appropriate for the size of boat, I hope to entertain 40 mph when im done
