Mercruiser 3.7 (165) running 180 degress out of time?

[structural1]

Guys this has me stumped. I just bought a boat with an 86 Merc 3.7 (165) 4 cylinder. I know the history on these damn engines but it was cheap and came with an Alternator conversion kit (not installed yet) and Pertronix Ignition (wires and pick up using original coil) and the larger 4" heat exchanger. When I bought it it would crank with about 1/3 throttle but run rough as hell. Sounded like it was out of time and maybe had a bad plug. I brought it home and put new plugs in it, changed the oil and filter and the fuel/water seperator and put a Flamethrower coil on it. Then I noticed something odd. The former owner had numbered in silver marker the cylinders from front to back 1,2,3,4 then numbered the distributer cap in the same way. But instead of #1 on the dist cap being directly in the front of the engine then in a clockwise rotation #2, #4, and #4 as the manual states and as I have found on this forum.... he had everything numbered and hooked up 180 degrees out. So #4 was in the front where 1 should be and 1 was in the back where 4 should be and 2 and 3 were swapped as well.

I wanted to make sure that at least we were close on timing so I rotated the engine to TDC #1 (I assume on the compression stroke) and I adjusted the distributor about 1/4" and the rotor is pointing almost directly forward to where the former owner had #4 wire.

Oddly enough she cranks right up, idles at about 950, and is as smooth as can be. If I swap the wire to where they traditionally should be (180 degrees from where they are now).... She spins over and pops out of the carb and exhaust and doesn't even try and crank.

Is she running 180 degrees out? Or did the former owner put the distributor in 180 degrees out but then just swap the wires to match the 180 degrees out?

What do you gusy think?

 

[Bondo]

Re: Mercruiser 3.7 (165) running 180 degress out of time?

Guys this has me stumped. I just bought a boat with an 86 Merc 3.7 (165) 4 cylinder. I know the history on these damn engines but it was cheap and came with an Alternator conversion kit (not installed yet) and Pertronix Ignition (wires and pick up using original coil) and the larger 4" heat exchanger. When I bought it it would crank with about 1/3 throttle but run rough as hell. Sounded like it was out of time and maybe had a bad plug. I brought it home and put new plugs in it, changed the oil and filter and the fuel/water seperator and put a Flamethrower coil on it. Then I noticed something odd. The former owner had numbered in silver marker the cylinders from front to back 1,2,3,4 then numbered the distributer cap in the same way. But instead of #1 on the dist cap being directly in the front of the engine then in a clockwise rotation #2, #4, and #4 as the manual states and as I have found on this forum.... he had everything numbered and hooked up 180 degrees out. So #4 was in the front where 1 should be and 1 was in the back where 4 should be and 2 and 3 were swapped as well.

I wanted to make sure that at least we were close on timing so I rotated the engine to TDC #1 (I assume on the compression stroke) and I adjusted the distributor about 1/4" and the rotor is pointing almost directly forward to where the former owner had #4 wire.

Oddly enough she cranks right up, idles at about 950, and is as smooth as can be. If I swap the wire to where they traditionally should be (180 degrees from where they are now).... She spins over and pops out of the carb and exhaust and doesn't even try and crank.

Is she running 180 degrees out? Or did the former owner put the distributor in 180 degrees out but then just swap the wires to match the 180 degrees out?

What do you gusy think?

Ayuh,.... The distributor don't care where #1 is, so long as it's at Tdc, #1 cylinder, 'n the order is right...

 

[Eric 3.7LX Alpha 1]

Re: Mercruiser 3.7 (165) running 180 degress out of time?

Guys this has me stumped. I just bought a boat with an 86 Merc 3.7 (165) 4 cylinder. I know the history on these damn engines but it was cheap and came with an Alternator conversion kit (not installed yet) and Pertronix Ignition (wires and pick up using original coil) and the larger 4" heat exchanger. When I bought it it would crank with about 1/3 throttle but run rough as hell. Sounded like it was out of time and maybe had a bad plug. I brought it home and put new plugs in it, changed the oil and filter and the fuel/water seperator and put a Flamethrower coil on it. Then I noticed something odd. The former owner had numbered in silver marker the cylinders from front to back 1,2,3,4 then numbered the distributer cap in the same way. But instead of #1 on the dist cap being directly in the front of the engine then in a clockwise rotation #2, #4, and #4 as the manual states and as I have found on this forum.... he had everything numbered and hooked up 180 degrees out. So #4 was in the front where 1 should be and 1 was in the back where 4 should be and 2 and 3 were swapped as well.

I wanted to make sure that at least we were close on timing so I rotated the engine to TDC #1 (I assume on the compression stroke) and I adjusted the distributor about 1/4" and the rotor is pointing almost directly forward to where the former owner had #4 wire.

Oddly enough she cranks right up, idles at about 950, and is as smooth as can be. If I swap the wire to where they traditionally should be (180 degrees from where they are now).... She spins over and pops out of the carb and exhaust and doesn't even try and crank.

Is she running 180 degrees out? Or did the former owner put the distributor in 180 degrees out but then just swap the wires to match the 180 degrees out?

What do you gusy think?

So you don't know if you infact had it at #1TDC on compression??

Pretty easy... pull the #1 plug, rotate the engine by hand "clockwise from the front" with a finger over the plug hole until you feel air push your finger off (or want to). Keep rotating slowly until the timing marks line up with 0? (should be close).

mark the center of each post of the cap on the lower half of the body (below the cap). Remove the cap, and the rotor should be very close to one of the post marks. That would/should be #1 cylinder on the dizzy.

Like Bondo said... you can make any post on the dizzy #1 so long as the rotor hits the post at the correct time and the firing order is correct.. doesn't matter. Dizzy rotation is also clockwise

 

[stonyloam]

Re: Mercruiser 3.7 (165) running 180 degress out of time?

Is she running 180 degrees out? Or did the former owner put the distributor in 180 degrees out but then just swap the wires to match the 180 degrees out?

What do you gusy think?

I think you had it TDC on the exhaust stroke. Yeah the distributor was probably installed 180 out, but as the guys above said as long as the rotor points to the #1 wire at TDC compression #1 piston it does not make any difference. BTW the cap should be marked as to which is the #1 plug wire.

 

[structural1]

Re: Mercruiser 3.7 (165) running 180 degress out of time?

You guys are awesome. Thanks. So the Previous owner had the dist 180 degrees out and then wired it to match. It cranks right up and idles fine now. thanks again.