Never heard of this in relation to a dizzy...you guys?

[MakDiesel]

I've been looking (for what seems like months now) on upgrading my 240's point distributor w/ an elect. one off of a ZX. Ok, I know I need an E12-80 module but someone sent me an offer and said theirs had an advance cam of 8.5...ok my Q is wtf is that? I've heard of advance curve, vacuum advance, advance/retard, cam lift, etc but never advance cam (i'm assuming 8.5 is degrees of something) Jus wonderin if someone could clue me in...also tell me what 'advance cam' I need for a bone stock '72 240 with good ol' SU's and a damn 3-sp slushbox. thanks in 'advance' AD

[sjcurtis]

MakDiesel,

I think what the guy was meaning by the statement is that it is the distributor for a 1981 or1982 ZX set for 8.2 degrees BTDC at 700 + or - 100 RPM. For the 240Z still set it up with standard timing position 10-17 degrees BTDC depending on fuel and altitude. its going to be around 15 plus with this particular distributor.

hope that helps

cheers

Steve:classic:

[Bambikiller240]

Originally posted by MakDiesel

.......said theirs had an advance cam of 8.5...ok my Q is wtf is that? I've heard of advance curve, vacuum advance, advance/retard, cam lift, etc but never advance cam (i'm assuming 8.5 is degrees of something) Jus wonderin if someone could clue me in...also tell me what 'advance cam'

I suspect that what he was referring to was the amount of centrifcal (sp) advance that is built into the distributor. There is both vacuum advance and centrifical advance, plus the mechanical advance that you set with your timing light which taken all together make up the TOTAL advance that can be applied to your engine as it runs.

[Victor Laury]

Right Carl,

He's reffering to the distributor cam, the little cam with the lobes that open the points. On Datsun dizzies, the centrifugal advance is mounted on this. Distributor Advance = Centrifugal Advance CA). This figure is multiplied by 2 for crank advance. 8.5 X 2 = 17 degrees.

Now our cars, as well as most others, on pump gas, run with a Total Advance (TA) between 28 ~ 35. Compression, cam lift and duration, mixture and altitude will effect the setting of TA. But, I would not exceed 35 on a stock engine. If you have a WILD, full on racing cam, you may not be able to start a car with less than 35 degrees TA. But a stocker, on pump premium might knock itself to death.

So let's use a benchmark starting point of a 32 degree TA. and fine tune it later.

32 TA - 17 CA = 15 degrees initial timing (at idle).

INITIAL TIMING - Is the point where the distributor is set in the engine prior to start-up. This timing can be advanced or retarded by moving the distributor.

CENTRIFUGAL ADVANCE - Is a function of the engine RPM and will increase as the engine's RPM increases. The centrifugal advance is controlled by the weights and springs insides the distributor.

TOTAL ADVANCE - Is the total of initial advance, centrifugal advance added together.

[sjcurtis]

WOW, I got of the side on that one. Great explanation Guys.

appologys

Steve:stupid: