timing meter help

[jtate]

ok im confused with the timing meter that i have. its a snap-on MT1480 lumy/mag ll. when i power it up with the magnetic pickup and the luminosity probe hooked up and a 20* offset, i can get two different readings depending on which way i turn the pump. if i turn the pump one way it will read like (neg 1.0) and if i turn it the other way it will read (1.0). which way is the correct way its supposed to read?

 

[icanfixall]

The pump is advanced when you turn it towards the passenger fender. Towrads the drivers fender it is retarding it. Are you reving it to 2000 rpm and setting the offset to -20 degrees? Now if all this is correct set it for 8.5 degrees before top dead center. BTDC. Just make sure the motor has warmed up and the cold advance has shut down. That happens at around 140 degrees coolant temp.

 

[jtate]

that may be the case for the pulse method but not luminosity. what im trying to figure out is when the meter reads (neg 1.0) is that atdc or btdc. you would think btdc, but the more you rotate the pump to the pass side the more noise the engine makes like predetanation. right now im about 3/16 to the pass side of the truck from the scribe mark and i still havent reached the infamous (1.0) atdc at 1400 or 2000rpm's.

 

[icanfixall]

If you use the luminosty method then you want the timing set retarded. The meter will show it at after top dead center. By what you have posted the turning it 3/36 inch towards the passenger fender is making it really advanced. The timing is very sensative and easy to go too much either way. I personally have never done the timing with the luminosty method so I'm not that much help. Others will chime in if they haven't gone to the ralley. I was going but just my fuel costs would have been $3000.00 getting 16 mpg... I'm putting that money towards a Gear Vendors....

 

[jtate]

that brings me back to my same question. after top dead center is that the (neg) or the (pos) side of the meter? so what your saying is +0.5 is atdc?

 

[jtate]

today i did another try at setting the timing with the meter i have. this is what ive got, at idle it reads (+5.5*) and as i bring it towards 2000rpm i can get it to read (-1.0*) at 2000rpm. does this sound right?

 

[jtate]

ok nobody has any insight on this particular subject.