Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

[BlakeBecker37130]

New member looking for a helping hand. I recently decided to do do an ignition tune up on my 1986 140. I have never played with points or timing but have the shop manual, tools and the job instructions look straight forward and easy enough. The engine was operating fine with the old parts, they just looked worn and in need of replacement. I pulled the cap, rotor, points and condensor. I replaced all of these things and set the dwell for the points with my meter around the middle range of 30-31 deg. When I put every thing back together the boat would not idle only sputter shake and run very rough, backfire through the carb etc. I did not have a timing light, but decided to loosen the distrib. and adjust it a bit. This only made thngs worse. Since this I have tried just about every thing. I lined the timing marks up @ 6 deg btdc
and rotated the distrib to match the #1 plug wire with the rotor. Still wont run I have a timing light now but cant even keep it running long enough to see the timing marks? Did I possibly mess up the valvetrain with my initial distb. adjustment. Im @ a loss of what to do next. Any info on this would sure be a great help

 

[Bondo]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

New member looking for a helping hand. I recently decided to do do an ignition tune up on my 1986 140. I have never played with points or timing but have the shop manual, tools and the job instructions look straight forward and easy enough. The engine was operating fine with the old parts, they just looked worn and in need of replacement. I pulled the cap, rotor, points and condensor. I replaced all of these things and set the dwell for the points with my meter around the middle range of 30-31 deg. When I put every thing back together the boat would not idle only sputter shake and run very rough, backfire through the carb etc. I did not have a timing light, but decided to loosen the distrib. and adjust it a bit. This only made thngs worse. Since this I have tried just about every thing. I lined the timing marks up @ 6 deg btdc
and rotated the distrib to match the #1 plug wire with the rotor. Still wont run I have a timing light now but cant even keep it running long enough to see the timing marks? Did I possibly mess up the valvetrain with my initial distb. adjustment. Im @ a loss of what to do next. Any info on this would sure be a great help

Ayuh,... Check the firin' order, 'n make Sure you got it Right,...

 

[Don S]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

I replaced all of these things and set the dwell for the points with my meter around the middle range of 30-31 deg. When I put every thing back together the boat would not idle only sputter shake and run very rough, backfire through the carb etc

You can't check or set dwell without the engine either running or cranking. Recheck the dwell with the engine running and see what you have.

Do you have a Delco or Prestolite distributor?

 

[BlakeBecker37130]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

Ayuh,... Check the firin' order, 'n make Sure you got it Right,...

firing order is correct 1-3-4-2

 

[BlakeBecker37130]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

You can't check or set dwell without the engine either running or cranking. Recheck the dwell with the engine running and see what you have.

Do you have a Delco or Prestolite distributor?

Delco

 

[BlakeBecker37130]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

Delco

Also, I checked the dwell while cranking and rough running the motor.

 

[Don S]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

Delco

Yes, that is the correct firing order. Check the dwell, it could be way off.

 

[BlakeBecker37130]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

Yes, that is the correct firing order. Check the dwell, it could be way off.

Dwell reads 30-31 deg. on my meter?

 

[BlakeBecker37130]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

Just wondering if really bad timing can trash the valves, pushrods, lifters, timing gears etc, or am I getting myself worried over somethng minor.

 

[Don S]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

Yes timing can hurt the engine.
The order of doing things after starting engine.

1. Confirm dwell setting.
2. Set idle timing (~650rpm).
3. Adjust idle mixture and speed.
4. Check advance timing.

EDIT: One note on the dwell. If you rev the engine a few times, keep an eye on the dwell meter. It should stay within a degree of where you set it. more change means the bushings in the distributor are worn.

 

[BlakeBecker37130]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

Yes timing can hurt the engine.
The order of doing things after starting engine.

1. Confirm dwell setting.
2. Set idle timing (~650rpm).
3. Adjust idle mixture and speed.
4. Check advance timing.

EDIT: One note on the dwell. If you rev the engine a few times, keep an eye on the dwell meter. It should stay within a degree of where you set it. more change means the bushings in the distributor are worn.

How can you tell when you've done damage to the motor?

 

[BlakeBecker37130]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

How can you tell when you've done damage to the motor?

Also: I can confirm dwell but after that it sputters and shakes to a halt, I try to make micro adjustments to the distributor to keep it running to no avail? Thanks for all of the insight so far but this thing has got me whipped right now!

 

[Don S]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

What happens to the dwell when you bring the rpms up to around 2000 rpm?

What rpm are you idling at?

 

[BlakeBecker37130]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

I do not think I can get it to 2k with out it quitting. It tries to idle around 800 rpm.

 

[Don S]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

Hook up the dwell meter, start the engine and let it warm up, then start increasing the throttle and watch the dwell meter, what does it (the dwell meter) do? Does it change?

 

[Don S]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

When you replaced the points, did you have a piece left over from the new points kit, kind of shaped like a C ?

 

[BlakeBecker37130]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

All of my answers so far are form last nights trials. I am @ work right now, but will try this when I get home. Truthfully I do not think it is even close enough in time to stay idiling for over 2 min. Last night when I tried to give more rpm I notticed a change in about 1 deg, but I could not keep it running long enough to decern anything. I have not touched the carb idle screw at all. It is still set @ it's orig. setting form the previous ignition components. Do I need to adjust it? Im trying to not compound the problem and get deeper in the weeds if @ all possible

 

[BlakeBecker37130]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

When you replaced the points, did you have a piece left over from the new points kit, kind of shaped like a C ?

No sir, They sent a feeler guage with the kit , but thats it.

 

[BlakeBecker37130]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

Are there any methods I can try that do not require the boat to be running to determine if everything is still intact. That way I do not have to keep beating the starter up.

 

[Bt Doctur]

Re: Problem timing an 86 mercruiser 140 after replacing points,cap,rotor Help!

try setting the point gap at .018 or the thickness of a matchbook. That way works only IF you set the engine to #1 TDC compression stroke.
"and rotated the distrib to match the #1 plug wire with the rotor"