Adjusting points on 305D with dwell meter

[Clarke]

Hello to the Group,

Over the weekend I tuned up the engine per the manual (torque head bolts, adjust valves, adjust points, timing, etc...). Truck has been running just fine; just running through the tune up process, in preparation for some longer trips.

When I first hooked the dwell meter up, it was reading 27 degrees. As I was adjusting the points to 33 degrees, the RPM of the motor started dropping at around 29 degrees. I didn't check the RPM before and after, so I do not know how much it dropped; I could just hear it (maybe 50 RPM?). The motor was not sputtering, just dropped in RPM. I revved the engine up and down several times while watching the dwell meter and it held steady on 33 degrees.

I'm not worried about it; truck still runs good. I was just curious if this is normal, or if anyone else has experienced the same? I guess I wasn't expecting the RPM to drop like it did when correcting the degrees.

Thanks in advance.

[Corts60]

As a general rule, I am always happy with the dwell set anywhere between 28-32 degrees. Usually the engines are as happy as I am too.

[Corts60]

Oh yeah, WELCOME!

[raycow]

I was just curious if this is normal, or if anyone else has experienced the same? I guess I wasn't expecting the RPM to drop like it did when correcting the degrees.


Totally normal. As you increase the dwell angle, you are retarding the timing. This is because the points are closing earlier and opening later. Your 6 degree increase in dwell retarded the timing by 3 degrees. That's what made the engine run slower.

First, set the dwell where you want it. Then reset the timing to spec.

Ray

[Clarke]

Thanks Corts60 and raycow... Yes, I did set the dwell first, then adjusted the timing.

By the way, I'm very happy with my compression test results:
#1 = 138
#3 = 139
#5 = 142
#2 = 142
#4 = 138
#6 = 140


David Clarke
1962 1500 Wideside