OMC 260 spark plugs for reading

[bruceb58]

Re: OMC 260 spark plugs for reading

I will bet he does.. I see a dwell meter purchase in his near future....

I would be very interested in seeing if the dwell is steady. Could be worn bushings in the distributor causing the timing to be so touchy.

 

[floattest]

Re: OMC 260 spark plugs for reading

Nope, it's a breakerless. I didn't mean to imply that the timing is not steady. It's rock steady at all rpms. I meant that it was difficult to make very small adjustments. every time I tried to move it 1 degree when I put the light on the crank the result would be 2 degrees of adjustment. A helper may have been a good idea so they could watch the timing marks as I adjusted.

Anyway it's set where I want it now.

And thanks for the idea on the tach, I'll be surprised if it's not set on 8 cyl. but it needs to be verified.

the post below details what I did to the ignition system a couple years ago.

Right now I'm just trying to fine tune it.

Any thoughts on the advance numbers I gave?

thanks

http://forums.iboats.com/mercruiser...ochester-carb-rebuild-415089.html#post2910328

 

[floattest]

Re: OMC 260 spark plugs for reading

" I'll be surprised if it's not set on 8 cyl. but it needs to be verified."

Well, I was able to climb up under the dash and determine that the tach has four settings. 1, 2, 3 and 4. It's set on 4.

I'm assuming that is correct. I don't know what other setting I would move it to.

Next time out I'm going to take an aux tach with me and try to figure out the difference between reality and what my tach is saying.

Anybody know why my tach might be off so much.

Going by my digital timing light, the tach reads about 4400 when the timing light reads 3200.

 

[floattest]

Re: OMC 260 spark plugs for reading

I don't know about the tach, but I know it's wrong.

Was able to get out another winter day of boating last Saturday. Wanted to run it under load with the correct timing, and the annual fuel system maintenance, also changed the oil, would do that normally in the fall, but I kept the boat on-line through the winter.

After this run I also took a few pics of 4 of the plugs.

This was a simple two hour cruise. Approximately 14 miles of water covered. About half was idle running and about half was cruise in the range of 32 mph.

Engine ran flawless. Lots of smooth power and no sign of pinging or detonation on the plugs.

The verification of the dash tach shows that it is about 25% off.

At 4500 on the dash tach, was actually running 3250 on the timing light tach, at 33mph.

At 5K on the dash tach, at 37 mph, still below 4K on the good tach.

Even at idle, the dash tach about 750, actual about 550.

Oh well, at least I know about where it is.

On to the plugs, They look great, except that one little plug from the 5 hole. seems odd. Enjoy the pics!

FT