distributers

slats · 10-16-2002, 11:23 AM

What is the difference between a mechanical advance distributor and a vacuum advance distributor? Does it effect performance and reliability?

thunderbolt · 10-16-2002, 04:34 PM

Most old non-computer aided distributors have one or two mechanisms for advancing the timing. The first is mechanical, and the second, which may or may not be there is vacuum. The distributor is rotated and clamped down, and where it is set is its initial timing. Changeing the position of the base of the distributor will change the initial timing, either advancing or retardind depending on direction.

Then inside the distributor is a movable shaft with the rotor on it. Connected to this movable shaft are two counter weights with springs. As the distributor spins faster the weights try to move further and further out. As they move, they advance the timing. Opposing this movement are the springs. So changing weights or springs can change how the mechanical advance comes on. Then, most distributors have a vacuum canister on the front which is also connected to the movable shaft inside the distributor. As the engine experiences different amounts of vacuum (wide open, no vacuum, crusing down the highway, lots of vacuum) the vacuum canister adjusts the timing.

Vacuum advance is generally for fuel efficency. Mechanical advance controls the engine during acceleration. Many performance distributors may only have mechanical advance.

slats · 10-16-2002, 06:47 PM

Thank you Thunderbolt. You have been great help.

10-16-2002, 11:23 AM	#1
slats Registered Member Join Date: Oct 2002 Location: Charlotte, N.C. Posts: 8	distributers What is the difference between a mechanical advance distributor and a vacuum advance distributor? Does it effect performance and reliability?

10-16-2002, 04:34 PM	#2
thunderbolt Registered Member Join Date: Oct 1998 Location: Houston, TX, USA Posts: 380	Most old non-computer aided distributors have one or two mechanisms for advancing the timing. The first is mechanical, and the second, which may or may not be there is vacuum. The distributor is rotated and clamped down, and where it is set is its initial timing. Changeing the position of the base of the distributor will change the initial timing, either advancing or retardind depending on direction. Then inside the distributor is a movable shaft with the rotor on it. Connected to this movable shaft are two counter weights with springs. As the distributor spins faster the weights try to move further and further out. As they move, they advance the timing. Opposing this movement are the springs. So changing weights or springs can change how the mechanical advance comes on. Then, most distributors have a vacuum canister on the front which is also connected to the movable shaft inside the distributor. As the engine experiences different amounts of vacuum (wide open, no vacuum, crusing down the highway, lots of vacuum) the vacuum canister adjusts the timing. Vacuum advance is generally for fuel efficency. Mechanical advance controls the engine during acceleration. Many performance distributors may only have mechanical advance.

10-16-2002, 06:47 PM	#3
slats Registered Member Join Date: Oct 2002 Location: Charlotte, N.C. Posts: 8	Thank you Thunderbolt. You have been great help.