M880 timing

[N1265]

Hi guys,

I just rebuilt the carb on the M880 and I'm re adjusting the timing . The book calls for 2 deg ATDC but the contact maintance manual that I have has 3 deg BTDC written in .

I have read post on other forums where guys are setting their 318 at 12 deg BTDC but am not sure what year truck they are working on.

So my question is : where do you guys run your timing at on your stock M880 set up ?

Many Thanks,

 

[WillWagner]

While I don't have an 880, i'd say try it around 10, or do the ear tune method. Advance it 'till it pings on a hard acceleration, then back it off a bit. Make sure to check that the advance wts are working also.

 

[maxim]

Mine runs fine with about 2 degrees. Stock carb stock engine. Make sure the vacume lines do not leak. There may be a sweet spot it likes run at, To much advance or retarded timing makes it knock and erratic idle.
​

Table 13-1. Distributor Test Points​

Part number 3755201
Rotation . . . . . . . . Clockwise
Firing order. . . . . . . . 1-8-4-3-6-5-7-2
Centrifugal advance . . . . . 0.5° to 3.0° @ 550
(degrees at 2.5° to 5.0° @ 700
distributor rpm) 11.5° to 14.0° @ 2150
Vacuum advance . . . . 0.5° to 2.5° @ 10 in
(degrees at inches 7.5° to 9.5° @ 15 in
of mercury)
Shaft side play. . . . . . . Not to exceed 0.006 in​

Shaft end play . . . . . . . 0.003 to 0.017 in