Logo
FULL SITE MENU

5.0 LX 1987 mercruiser timing

F

fsamie1

Member
I need help to do timing. this engine has ignition module inside the distributor. using timing light, I set it to 8 degrees before TDC at 750 rpm and it does not runs good and backfires through exhaust. it runs much better when set at like 20 degrees advance. Very confusing because manual calls for grounding pur/wht wire to do base timing. I looked all over for pur/wht wire and just not there. Ordered new distributor, rotor, coil, ignition module and hoping I get lucky. I appreciate any help with this puzzle.
 
Very confusing because manual calls for grounding pur/wht wire to do base timing.
Click to expand...

Ayuh,..... That's for the T-Bolt V,..... Yer motor should have the T-Bolt IV ignition, which is just point, shoot, 'n time,.....
 
considering the timing mark moves counterclockwise when you advance the throttle exactly how are you reading the 20 degrees of advance? Are you positive you have #1 wire hoked up?
 
#1 hooked up, marker moves counter clockwise from TDC.

No points, it has ignition module. It has TB V ignition, I think

New wires
 
I still think you are getting cross firing somehow, for that would explain everything that's going on.

See that your new wires are separated and not cross firing on you. You can put "snake skin" around the wires where they touch to make sure.

Jeff

PS: 'Snake skin' is a plastic corrugated material that's slit open along its length. Any good auto parts store sells it. Get the smallest size that will go on your wires.
 
fastjeff said:
I still think you are getting cross firing somehow, for that would explain everything that's going on.

See that your new wires are separated and not cross firing on you. You can put "snake skin" around the wires where they touch to make sure.

Jeff

PS: 'Snake skin' is a plastic corrugated material that's slit open along its length. Any good auto parts store sells it. Get the smallest size that will go on your wires.
Click to expand...

Thanks Jeff, That makes sense because when changed wires it ran decent 3300 rom and 24 mph, but when I put in new plugs next day and messing with new wires a little bit, it ran very bad.
 
fsamie1 said:
Thanks Jeff, That makes sense because when changed wires it ran decent 3300 rom and 24 mph, but when I put in new plugs next day and messing with new wires a little bit, it ran very bad.
Click to expand...
Based on that comment likely two wires got mixed up when you changed the plugs. Double check the firing order
 
Back
Top