Timing Question

[naa10104]

hello,

Have a 351 - C 2V motor. Was going to check my timing, but so not presently have a timing light. I was told by a mechanic that using a vacumn guage was actually a better way to adjust the timing. So I connected a vacumn guage to the hose which leads to the vacumn advance on the distributor ... no vacumn indicated. I then connected to the hose which goes to the valve/damper(?) on the air cleaner snorkel. Needle moved a little but not enough to utilize for timing adjustment. Anyone tell me what I am doing wrong ... sure I am ! Thanks

 

[jbojo]

I have always used the manifold vacumn. I believe that the distributor is ported vacumn so no vacumn at idle.

 

[Qcode351mach]

Umm vacuum gauge to set timing ? I think not..You use the vacuum gauge to set your carb idle screws..Diagnose engine issues..You use a timing light to set your timing. buy or borrow a timing light.

 

[72HCODE]

you can set timing with a vacuum gauge.

however i do not recommend it. it requires setting up the motor a certain way with idle and it is very easy to screw up and add much too much advanced timing.

highest vacuum at idle means most efficient fuel/air mixture, however most efficient does not mean the engine will be running correctly usually it is too lean.

a vacuum tune is also sensitive to atmospheric conditions on the day you do it.

additionally you will need to use full manifold vacuum to setup the gauge, not ported, ported is 0HG" at idle, full manifold can be 10-25HG" at idle depending on a combination of things.

use a timing light. it will give you the most stable ignition timing over a very wide range of temperature and humidity.

more initial timing to a point means more power. however it is more dependent on what the engine can tolerate.

usually initial timing is set from 4 to 20 degrees, but again depends on a huge combination of things, your harmonic balancer might have a timing mark on it set by the last builder of the engine it depends on the cam so to be safe you stick with that.

it is possible to mess around too much and grenade the engine with too much timing, no timing limit, and the engine leaning out.

 

[naa10104]

you can set timing with a vacuum gauge.

however i do not recommend it. it requires setting up the motor a certain way with idle and it is very easy to screw up and add much too much advanced timing.

highest vacuum at idle means most efficient fuel/air mixture, however most efficient does not mean the engine will be running correctly usually it is too lean.

a vacuum tune is also sensitive to atmospheric conditions on the day you do it.

additionally you will need to use full manifold vacuum to setup the gauge, not ported, ported is 0HG" at idle, full manifold can be 10-25HG" at idle depending on a combination of things.

use a timing light. it will give you the most stable ignition timing over a very wide range of temperature and humidity.

more initial timing to a point means more power. however it is more dependent on what the engine can tolerate.

usually initial timing is set from 4 to 20 degrees, but again depends on a huge combination of things, your harmonic balancer might have a timing mark on it set by the last builder of the engine it depends on the cam so to be safe you stick with that.

it is possible to mess around too much and grenade the engine with too much timing, no timing limit, and the engine leaning out.

Thanks to all for your respnses !!