Here in New Jersey, I always struggled to get my 78' Spider through the state emmissions test as it has twin Webbers. I leaned the carbs out as best I could with jetting and settings and still it would fail. What ultimately worked was eliminating valve overlap/scavenging (the slight moment when both valves are open at end of exhaust stroke and start of intake stroke) by advancing the exhaust cam and retarding the intake cam by approximately three widths of the timing marks on the cams/caps. After doing so, the car ran much leaner and I was able to pass the NJ emmissions test, however, as soon as I got home I readjusted the cams back to the factory setting as running too lean for extended periods can result in catastrophic failure not to mention the loss of performance due to the elimination of the scavenging effect. You might consider this strategy for enhanced fuel economy, perhaps not so aggressively, maybe one width of the timing mark on each cam and see what your result is before adjusting further. Ensure that your resecure all of the cams'/vernier wheels' lock nuts/cotter pins/etc after each adjustment to avoid anything coming apart in operation. Best of luck.
1978 Spider (Triple Black/the good sports car)
1969 E-Type(Silver+Cinnamon/the evil sport car)
You can pick up 11 degrees on the intake cam by simply disconnecting the VVT solinoid. (provided yours is electronic and not the mechanical centerfuge version)
Well, 'pick up' is the wrong phrase. More like prevent an 11 degree advance, or, leave the cam 11 degrees retarded. However you want to look at it. :shrug:
That way it'll never kick into power mode and stay in the much 'softer' econo/closed loop (and better emissions) mode most all the time. There will still be a bit of open loop enrichment when you honk down on the throttle, but the intake cam won't kick over to the suck fuel degree index.
I suppose one could even disconnect the full throttle contact at the TPS also so that it didn't even get into an enrichment/open loop mode, but I'd imagine that would turn the car into a downright pig.
Well, actually, no 'imagine' about it, it would turn it into a pig. But hey, if it's mileage you're after, then sacrifices must be made, right?
Still, in a proper state of tune, you should be seeing milage in the upper 20's if not 30mpg range.
If you're not getting around that now, tinkering the cams is going to be far less benificial than an actual factual tune-up.
Make sure the Manifold Pressure Sensor (measures intake vacuum) is functioning. It is located under the trim panel behind the right side seat. If it is faulty (they've been known to leak) or its hose is cracked & leaking the ECU (computer) won't know to advance the igniton timing under cruise conditions. That'll reduce fuel economy.
i just drove from LA to Vegas with much luggage which primarily uphill as well and recorded 30 MPG. I'll see in a few days how it is since i will be driving more highway miles at a much lighter weight. i've read numerous of time from all those people with hybrids that are trying to set all their MPG records, that they allow hotter air into the intake among many other little tricks. figure, less density air, less fuel used, or hotter air, better fuel atomization. do you think adjusting the AFM spring for the flapper a little tighter is going to do anything? i've done a few mods already which don't necessarily help my gas mileage. i went from 26-27 before my mods/complete lookover and tune up. and then after, it dropped down to the low 20's. but that could also do with my heavy foot. i could definately feel a difference in power. but for the mean time, i'm more concerned with gas mileage right now. i'm running some goodyears which measure about an inch taller than stock at 25.2" in diameter. well, at least they were much taller than the tires that were on the car before. so i did this to reduce my RPM at highway speed so i could cruise at a higher speeds yet keep a lower RPM. i usually dont go above 3000 while shifting and cruise at 3000-3200.
Also pump up the tires as hard as you can, that can help. it might be just me but I think the headlight covers make a difference. and a hard top will also help with the drag some.
run as much timming advance as you can. changing the AFM should have no affect at cruise as you should be runing close loop with the NBO²
but it seems the spiders just do not get as good as MPG as the bigger Verde, seems strange.
try syn-oil all around that should also help some. rember to use the redline NS in the tranny.
every bit of drag adds up.
i'm pretty firm with the tires and i have a suspension stiffer than ever. my aerodynamic drag should possibly be lower also due to the ride height. i can't change the ignition timing on the L-jetronic. can you explain what the closed loop thing is with the NBO2? i've been running the Valvoline VR-1 20W-50 with a remote oil filter. also lined-in is a 180 degree thermostatic bypass to a massive oil cooler. i don't think my oil gets hot enough to create a large enough bypass through the cooler because after driving, i touch the cooler and the inlet is somewhat too hot to touch but the outlet is somewhat ambient. maybe its just really efficient? one thought was the oil thermostat is behind the radiator so its possibly getting false colder readings due to the ram air. so i was thinking of putting a plate in front of the oil thermostat to deflect the oncoming air. or maybe its just not working up to specs. i dont know, i need to mess with it some more.
do you know where i can get some headlight covers for this year alfa 83'?
i've look before back in the day with no luck.
You won't find headlight covers for the series 3 or 4, they just never made them and the tinwork around the lights is different enough to prevent any real bolt on of the older style lenses unless you want to fiddle around knocking tin or slathering bondo to close the gaps.
Closed loop is when the ECU gets it's signal from the O2 sensor and another signal from the TPS that tells it that you're not up on the gas or at idle. (there's a trigger signal from the TPS at idle and at 55 degrees & up throttle deflection. Stay between those points and the ECU will try to go into closed loop)
The ECU 'reads' the O2 signal and corrects the A/F mixture to stoich, which is 14.7:1. (supposedly the be all end all for efficiency, economy and emissions)
Fiddling around with the AFM 'may' cause the ECU to not be as efficient at maintaining closed loop, so it can be more harmful than benificial. (though the ECU does work over a pretty broad A/F range, so it may be possible to improve on things if you've got time to do a few dozen tanks of gas to prove one way or the other)
does it have a timminging wheel on the crank? (front pully)
on the V6 the L-jet got the timming off the dizzy so if it was moved the timming would move too.
if you can not bump the timming try a lower grade of gas. if you do not ping the lower grade will give more power. so you should use less.
and it cost less.
one thing that might help some it to use newer type injectors. but you would have to convert to a rail.
the BMW guys say they get a few more MPG by puting in some newer ford type injectors that seem to mist up the gas more. they get them used off ebay. but I think they are Hi-Z the L-jet is Lo-Z
my guess is a peak-n-hold circuit will be fine with Hi-Z
Motronic ('90-'94) has a crank sensor at the front pulley. L-jet ('82-'89) has two flywheel sensors. Note that 'adjusting' the distributor will have no effect on ignition timing. The ECU controls that (based on info from the flywheel sensors & the vacuum sensor). The distributor functions only as a 4-way switch.