1981 mercruiser 120 dwell cant get it below 60 WOT low RPMs

[merc120_81]

hello all,

I have a 1981 Mercruiser 120, I have replaced points, condensor, cap, roter, plugs and wires.

When checking the dwell with a meeter, I am getting readings in the 60-63 range. the meeter has settings for 4, 6,8 cylander engines, I have it set on 4.

I tried point gaps up to .028 and down to .015. With very little change in dwell. the dwell doesn't waver it stays steady when I set the points.

What could I have possibly done wrong? I am using the smaller section of the distributor shaft as the high point, is this correct?

I started looking at the tuning parmeeters, because I am not getting fully to 3800-4400 rpms, I am hitting about 3100.

Boat is 1981 fourwinns Marquis 170 (16.5' fiberglass V bow rider) prop is turning point 14.5" 19P outdrive mc1 1:98 I believe.

THANKS

 

[dubs283]

Re: 1981 mercruiser 120 dwell cant get it below 60 WOT low RPMs

the point gap is measured at the widest opening of the points, i.e. when the largest part of the cam lob is touching the point arm

are you using a digital or analog dwell meter?? are the batteries good in the meter?? are you sure you have the correct points installed??

 

[Don S]

Re: 1981 mercruiser 120 dwell cant get it below 60 WOT low RPMs

Do you have the dwell meter hooked to the - terminal of the coil?

 

[merc120_81]

Re: 1981 mercruiser 120 dwell cant get it below 60 WOT low RPMs

Don S, the winner again..
I hooked up the meeter incorectly... I had red to + of coil and black to - of coil..

hooked it up correctly and got 24 .... need to go a little wider on my gap I suppose now..


Would Dwell effect WOT?

unfortunately I have to reset dwell and go for a run, as there was much mucking with the point gap before I got the meeter hooked up correctly... duh... THANKS All..

 

[merc120_81]

Re: 1981 mercruiser 120 dwell cant get it below 60 WOT low RPMs

the point gap is measured at the widest opening of the points, i.e. when the largest part of the cam lob is touching the point arm

are you using a digital or analog dwell meter?? are the batteries good in the meter?? are you sure you have the correct points installed??

Digital and brand new batteries, thanks.. I hooked up the meeter incorrectly...

 

[Don S]

Re: 1981 mercruiser 120 dwell cant get it below 60 WOT low RPMs

Would Dwell effect WOT?

Absolutely, it also affects timing. So after you get the dwell set, make sure you reset the base timing.

 

[merc120_81]

Re: 1981 mercruiser 120 dwell cant get it below 60 WOT low RPMs

Still trying to get back on the water, have set dwell, timing, and new plugs.. will report after I get her back on the water..

Boat is 1981 fourwinns Marquis 170 (16.5' fiberglass V bow rider) prop is turning point 14.5" 19P (2150 1930) outdrive mc1 1:98 , 1780lbs..

1981 Four Winns 170 MARQUISE Standard Equipment, Boat Value, Boat Price & Craft Specs | NADAguides

hoping its not too much prop.

 

[merc120_81]

Re: 1981 mercruiser 120 dwell cant get it below 60 WOT low RPMs

Got on the water today, with dwell at 30, timing 8 BTDC got 3800 on the 19P prop (33 mph) , thinking I will opt for the 17P prop. hopeing that will get me to 4200 or so.

 

[achris]

Re: 1981 mercruiser 120 dwell cant get it below 60 WOT low RPMs

Got on the water today, with dwell at 30, timing 8 BTDC got 3800 on the 19P prop (33 mph) , thinking I will opt for the 17P prop. hopeing that will get me to 4200 or so.

Good choice. You'll find the boat feels lighter and the engine more responsive. You might get 1 or 2 mph quicker too...

 

[merc120_81]

Re: 1981 mercruiser 120 dwell cant get it below 60 WOT low RPMs

Went to the 17p 14,25 turning point hustler 4blade... 4150 rpm 31. Mph. Boat feels nimble thank you everyone.