L-Jet going full Rich on Deceleration Options

[Brian Fuerbach]

1974 1.8 with L- jet. Been playing with a wide band air fuel meter and noticed that when I lift the throttle the AFR goes to max value on the gauge. I thought it was supposed to go lean. I checked the throttle position switch and it checks out fine. Going to check the wiring harness next.

What else should I check? Decel valve?

[Van B]

You guys just aren’t willing to talk about spark timing…
Riddle me this, why is timing retarded at idle conditions?

[wonkipop]

You guys just aren’t willing to talk about spark timing…
Riddle me this, why is timing retarded at idle conditions?

i agree.
double vac can distributor is an integral part of the emissions equipment.

part of a sequence.

a sequence that produces more hydrocarbons in initial combustion.
then burns them up kind of crudely on the way out the door.

have i got that right Van.
you have your head around this better than me.

[Brian Fuerbach]

You guys just aren’t willing to talk about spark timing…
Riddle me this, why is timing retarded at idle conditions?

i agree.
double vac can distributor is an integral part of the emissions equipment.

part of a sequence.

a sequence that produces more hydrocarbons in initial combustion.
then burns them up kind of crudely on the way out the door.

have i got that right Van.
you have your head around this better than me.

I understood that the retard was mostly for idle emissions. When I had mine hooked up the engine would get hotter if left idling. Never could get a consistent idle either. I have heard many say that it is required for the proper idle with L-jet but I tried and hated the tune.

[wonkipop]

You guys just aren’t willing to talk about spark timing…
Riddle me this, why is timing retarded at idle conditions?

i agree.
double vac can distributor is an integral part of the emissions equipment.

part of a sequence.

a sequence that produces more hydrocarbons in initial combustion.
then burns them up kind of crudely on the way out the door.

have i got that right Van.
you have your head around this better than me.

I understood that the retard was mostly for idle emissions. When I had mine hooked up the engine would get hotter if left idling. Never could get a consistent idle either. I have heard many say that it is required for the proper idle with L-jet but I tried and hated the tune.

no, not just idle if you happened to own a 74 cal 1.8 or any of the 75s. they were just vac retard connected. which meant the ignition was retarded any time you were in a manifold vac situation with the engine. ie cruise. or throttle shut down.

only the 74 1.8 49 state car had the advance hose actually hooked up to the t/b to give you a big vac advance at cruise/light load. mostly for economy and cool running.
but as soon as you closed the throttle the same scenario would go into play as per all the others with regard to distributor.

see van's masterful economical description.

the californians were using that retard to clean up emissions at cruise in 74.
and the rest of the USA was doing the same thing in 75.
with added EGR in california which did some stuff emery is right up on.


and yes brian it really does make them idle noticeably hotter.
spot on there.
so much so that i tend to avoid driving mine in high summer in australia where air temps get up easily into low 40C range.