FBO's black HEI ignition box
any mag pickup distributor will cause the advance to retard with RPM its the one slight negtive
the spinning reluctor, as it passes the pickup pole, gains its own magnetic field due to its movmnet past the magnetic pickup.
its own field distorts that of the pickup and as magnetic fields and the currents they induce in near by coils of wire is totally dependedent on the speed you cut through the lines of magnetic flux the induced magentisim in the reluctor star gets bigger the fast you go
this messes with the pickup field in a manner that results in the igntion timing reatarding slightly as RPM increses.
but this issue is totally outweighed by the benefit of a magntic pickup output haveing both timing and RPM information in it
timing is the trigger pulses,
rpm is the voltage size of the pulses
you don't get that with points OR hall effect pickups which are really just encoders of a position. thay in essence can only provide timing not rpm in a basic igntion.
the other retard that any electronic system adds to the equation is based on its function and is the same across the operable rpm range i.e its catered for when you set the poistion of the distributor in the block
i.e 5 btdc with a points distributor postion marked exactly will not be 5btdc with the electronic dizzy if marked and set into the block in excatly the sme position.
but you don't set timing based on position of distributor you use position of distributor to set the timing based on spark and damper TDC mark position. so its a moot point.
MSD type igntions do retard
you switch from 3 sparks to 1 spark at a specific rpm you sometimes see a retard when they change mode of operation. but as this is a race igntion they don't expect you to be racing in that rpm range.
i rambled on on this link but provided some links to more info
Dual-point vs. Single-point distributors - pros and cons?
hei looks at the size of the pluse and decides if its time to switch OFF its current limiting
an action that helps maintain the same spark power from idle to 6000 rpm
the limiting is designed to keep the coil cool, and to stop you cooking the coil if you leave the car igntion switch in RUN with the engine stalled.
the FBO box looks like a copy of the Lucas AB14 CEI ingtion box used on jaguars in the 70s/80s see picture below. note use of radio supression capcitor and a press fit zener diode in coil/module negative to act as a clamp.... (in the jag ab14 box below)
FBO's benefits from a nice modern and potentally the best 4 pin module and a mopar connector, but you can make one yourself usuing the guts of your old mopar igntion amp and any mid priced known brand 4 pin HEI.
big gap small gap
too big too small both bad
the aim is to have one that works at all rpms
hei specified 45 thou that was for the big chevy distributor with a diameter twice the size of a mopar.
35 thou seems ok on my six cylinder with a mopar dizzy. This size gap and a full HEI system with a reverse zener diode protection clamp has my car running leagues better because it now ignites mixtures that previously were un ignitable by the old igntion set up.... HEI was designed to make a chevy with a horrible restrictive first year of catalytic converters ... actullay run... and this on a motor where they didn't even have the mopar benefit of the valves being positioned to open into the widest diameter line, of the cylinder bore... think standard cam poor flowing inlet and a massively restictive exhaust.... none of us have those problems which means the ignition is going to be complete overkill... or as i like to think of it.....an upgrade.
if they used 4 pin HEIs on v12 jaguars, a mopar with reasonably sensible static CR should be no problem.
any mag pickup distributor will cause the advance to retard with RPM its the one slight negtive
the spinning reluctor, as it passes the pickup pole, gains its own magnetic field due to its movmnet past the magnetic pickup.
its own field distorts that of the pickup and as magnetic fields and the currents they induce in near by coils of wire is totally dependedent on the speed you cut through the lines of magnetic flux the induced magentisim in the reluctor star gets bigger the fast you go
this messes with the pickup field in a manner that results in the igntion timing reatarding slightly as RPM increses.
but this issue is totally outweighed by the benefit of a magntic pickup output haveing both timing and RPM information in it
timing is the trigger pulses,
rpm is the voltage size of the pulses
you don't get that with points OR hall effect pickups which are really just encoders of a position. thay in essence can only provide timing not rpm in a basic igntion.
the other retard that any electronic system adds to the equation is based on its function and is the same across the operable rpm range i.e its catered for when you set the poistion of the distributor in the block
i.e 5 btdc with a points distributor postion marked exactly will not be 5btdc with the electronic dizzy if marked and set into the block in excatly the sme position.
but you don't set timing based on position of distributor you use position of distributor to set the timing based on spark and damper TDC mark position. so its a moot point.
MSD type igntions do retard
you switch from 3 sparks to 1 spark at a specific rpm you sometimes see a retard when they change mode of operation. but as this is a race igntion they don't expect you to be racing in that rpm range.
i rambled on on this link but provided some links to more info
Dual-point vs. Single-point distributors - pros and cons?
hei looks at the size of the pluse and decides if its time to switch OFF its current limiting
an action that helps maintain the same spark power from idle to 6000 rpm
the limiting is designed to keep the coil cool, and to stop you cooking the coil if you leave the car igntion switch in RUN with the engine stalled.
the FBO box looks like a copy of the Lucas AB14 CEI ingtion box used on jaguars in the 70s/80s see picture below. note use of radio supression capcitor and a press fit zener diode in coil/module negative to act as a clamp.... (in the jag ab14 box below)
FBO's benefits from a nice modern and potentally the best 4 pin module and a mopar connector, but you can make one yourself usuing the guts of your old mopar igntion amp and any mid priced known brand 4 pin HEI.
big gap small gap
too big too small both bad
the aim is to have one that works at all rpms
hei specified 45 thou that was for the big chevy distributor with a diameter twice the size of a mopar.
35 thou seems ok on my six cylinder with a mopar dizzy. This size gap and a full HEI system with a reverse zener diode protection clamp has my car running leagues better because it now ignites mixtures that previously were un ignitable by the old igntion set up.... HEI was designed to make a chevy with a horrible restrictive first year of catalytic converters ... actullay run... and this on a motor where they didn't even have the mopar benefit of the valves being positioned to open into the widest diameter line, of the cylinder bore... think standard cam poor flowing inlet and a massively restictive exhaust.... none of us have those problems which means the ignition is going to be complete overkill... or as i like to think of it.....an upgrade.
if they used 4 pin HEIs on v12 jaguars, a mopar with reasonably sensible static CR should be no problem.
