Dwell on a mercruiser 165?

[KCKracker]

i keep getting told to check dwell, and i have a dwell meter, but how do i set it or check it on a motor that wont start yet? i dont know if its far off or set.

 

[Scott Danforth]

check it while cranking with distributor cap and rotor off. your checking the point dwell. should be able to check within 4 or 5 seconds of cranking

 

[KCKracker]

Thank you. ok so dumb question, i got a dwell meter, its old i havent used it in 20 years lol. i have 2 black leads where do they go?

 

[Lou C]

Positive lead from the meter goes to the coil negative terminal and negative lead goes to battery neg or any engine ground. Make sure to ground the coil lead from the dist cap as well.

 

[Bt Doctur]

Have never even looked at setting dwell, set the gap at .018 and go But then again how many know HOW to adjust points in the first place

 

[KCKracker]

i do not see a dwell adjustment anywhere, how do i set or change it ? the points only have one adjustment to set gap.

 

[Lou C]

ohh for the days of the GM Delco-Remy window dist design where you opened the lit metal window, slid in your flex allen wrench and set the dwell with the engine running.
Usually when setting it by the feeler gauge method, your gap winds up a bit too big which equates to not enough dwell. This can cause a weak spark at high revs because the dwell angle (degrees that the camshaft turns with the points closed, saturating the coil) directly affects the hotness of the spark.

Another good reason for checking it is that dwell affects timing. If the dwell and timing were set right and then you go and put in a new set of points and the dwell is off a bit (ie lets say the gap is a bit too big and the dwell is a bit too small) the timing will be advanced slightly from what was correct. Not a huge big deal but if you want it all right, do dwell, timing and then idle speed.

 

[KCKracker]

that makes sense but i still dont know how to "set" or adjust dwell:laugh:

 

[Scott Danforth]

that makes sense but i still dont know how to "set" or adjust dwell:laugh:

two screw drivers, one between the nubs and notch, the other on the mounting screw. all you are doing is fine-tuning the gap.

 

[KCKracker]

is there some kind of a write-up on this? i dont know what the nubs and knotch is or what id be doing with that screwdriver. i know the gap is dead on .017

 

[Scott Danforth]

look at the screw that holds your points. next to that is a notch that you can stick a second screw driver in. depending on the distributor, there is either another notch or two nubs. this is to fine tune the gap.

dead on 0.017 is fine for a starting point, however if the two surfaces are not perfectly flat, any angularity or pitting will change dwell.

I have found up to a 8 degree dwell change between "dead on" and where the dwell should be over the years.

 

[KCKracker]

ooook so its not really an adjustment more then "tweeking" it to sit flat.. ok. i did file them.

 

[Bt Doctur]

The contacts must be exactly flat with each other . Every .001 will change the timing 1 degree. Most were set/adjusted to 28-32 degrees of dwell. So start with your .017 setting , start the motor and check the dwell if you like. Then increase the gap to .018, .019, .020, etc untill your satisfied with the dwell reading and record what you actually set the points to

 

[hogbare35]

KC I'll tell you how I checked my dwell. I change to an electronic system. I have used old GM HEI systems and converted point dist to electronic systems. So much more reliable and easy to work on.

 

[KCKracker]

ya as soon as i get an answer about if my coil s in range or bad, im junking this old system!

 

[KCKracker]

i cant seem to get a response on my other thread maybe somneone in this one can tell me, coil test my primary test was 5.89 ohms on the 200 scale and secondary test was 8.50 on the 20k scale, is that ok? i cant find a spec
and i just tested power at my coil + side wires, i get 9V for just a few sec. then its gone, looks like the ballast took a dump gonna put in a new one i just got, they said 1.4 ohm drop was correct?

 

[Bt Doctur]

Values are dependent on the accuracy of your equipment.
Primary Winding
Non-ballasted coil about 3.2 ohms
Ballasted coil about 1.6 ohms

Secondary winding
7500- 10,000 ohms

 

[KCKracker]

i bought the mercruiser seloc the wiring diagrams dont seem to show where the original ballast is. is it a resisted wire maybe? idlike to take it out and run a new ign wire with the new ballast

 

[Bt Doctur]

the inline 4 uses wire and the inline 6 uses a ballast resistor
do you have a 4 or 6 cylinder

 

[KCKracker]

i have a 6 / 165 and cannot locate it. any idea what color wire its on coming from the ign. key or is it on the motor side of the harness?