MerCruiser 120 timing???

Bermanator

Recruit
Joined
Oct 15, 2017
Messages
1
Pulled the distributor out of my 1968 mercruiser 120. New points, condenser, coil. when I put it back in and set the timing, all I get is a backfire out of the carburetor. I've tried advancing and retarding the timing but there is no change. does anyone know what might be my issue? just bought this boat a few days ago and trying to get it running. nice strong spark, bottle feeding gasoline straight into the carb.
 

chevymaher

Commander
Joined
Mar 29, 2017
Messages
2,914
My best guess it you put it in a tooth or 2 off. Did it run right before you took it out?
 

fishrdan

Admiral
Joined
Jan 25, 2008
Messages
6,989
Is the distributor stabbed with with the rotor pointing to the distributor's #1 (cylinder) terminal, with the engine at TDC of #1 cylinder at the top of it's compression stroke? Spark plug wires in the correct firing order , 1-3-4-2?

Have someone crank the engine while turning the distributor slowly.
 

devildogae

Petty Officer 2nd Class
Joined
Jan 14, 2017
Messages
147
Is the distributor stabbed with with the rotor pointing to the distributor's #1 (cylinder) terminal, with the engine at TDC of #1 cylinder at the top of it's compression stroke? Spark plug wires in the correct firing order , 1-3-4-2?

Have someone crank the engine while turning the distributor slowly.

Is there a specific distributor position for the #1 terminal? I put #1 cylinder to TDC and had the distributor rotor pointing to the #1 cylinder spark plug hole, and used that location (Upper Right Hand Corner) for the #1 coil wire. I'm wondering if I did this correct, because I've seen several of the same motor where they used the Lower Right Hand Corner location for the #1 coil wire. Please help!
 

fishrdan

Admiral
Joined
Jan 25, 2008
Messages
6,989
Is there a specific distributor position for the #1 terminal? I put #1 cylinder to TDC and had the distributor rotor pointing to the #1 cylinder spark plug hole, and used that location (Upper Right Hand Corner) for the #1 coil wire. I'm wondering if I did this correct, because I've seen several of the same motor where they used the Lower Right Hand Corner location for the #1 coil wire. Please help!

"Normally" the distributor cap's #1 spark plug terminal points towards #1 cylinder. I say normally as this depends on if the distributor has been stabbed properly. The distributor should be stabbed so the rotor is pointing towards cyl #1, with cylinder #1's piston at the top of it's travel- on the compression stroke. You hay have to turn the oil pump drive bit to get the distributor to drop in all the way.
 

Alumarine

Captain
Joined
Feb 22, 2005
Messages
3,684
The rotor doesn't have to point to the number one cylinder, although it often does, just to the terminal on the distributor cap with a plug wire going to the number one cylinder.

And as fishrdan says, the piston should be at TDC on it's compression stroke.
 
Top