awadecki
07-13-09, 03:08 PM
Hi all,
I just made a 550-mile round trip in my 76 Eldorado with 51k miles. Car was a blast to drive. Just thought I'd share that I averaged 15.8 mpg with the cruise set at 68 mph and the A/C on about 1/3 of the time.
For an 8.2L V8 with a 3-speed auto, I couldn't believe the mileage! I get about 10 mpg city and almost 16 highway.
I've rebuilt the QJet carb, put in new Delco plugs, wires, cap & rotor, fuelt filter, air filter, fresh oil change, new fuel pump (old one worked fine, but didn't trust it for long trips), new ignition module in distributor (again, replaced preventatively--always keep a spare in my glovebox!), gutted the converter and resonator, set the timing at 8 degrees base instead of 6, and put on a big muffler that sounds great--not too loud or quiet, just right.
A couple of tips from my experience owning two 1976 Eldorados:
1. If you're having problems with your blower turning on while not in "Off" or "Lo", check for a loose connection at the "Auto Relay" on the driver's side of the evaporator case. Clean off the contacts and reattach. If this doesn't work, try a new "Auto Relay". They seem to go bad.
2. Keep the EGR valve and make sure the diaphram moves freely with firm pressure. This will allow you to run at about 8 degrees timing advance with no spark knock on 89 pump gas. This will increase power by about 5% and mileage by about 5% too.
3. Replace the primary choke pull of (vacuum break) on the carb. It's $15 and most of them are shot. This will lead to poor cold driveability as the choke won't open properly. Takes about 30 mins to replace.
4. Rebuild the QJet and make sure to seal the well plugs in the bottom of the float bowl. These start leaking after 30 years, creating long hot-start cranking times and that puff of black smoke on start up. Not to mention, you're wasting the gas that drains through the plugs into the intake. This will also help cold starts. Without resealing these plugs, the float bowl will drain, and you'll have to crank until the bowl is refilled. If my car sits for 3 days, all I need is ONE pump on the pedal to set the choke, and the car starts INSTANTLY. Instant hot starts, too! Rare for an old carbureted car.
5. If you've got a "sagger" in the rear, try filling the compressor on the passenger side to 90 psi. If the shocks air up, they may hold air. If the car sits for a long time, the compressor isn't strong enough to pump them up on its own.
6. If your car has cruise control and the speedo is jiggly/making noise, you probably need a cruise control transducer. This is also the case if, when you set the cruise, the car surges, then coasts. They cost about $120 and can be swapped in about 30 mins. I've owned 3 GM cars where I've had to replace this. If you don't replace it, the transducer will likely freeze, snapping the speedo cable from the trans.
7. For long trips, replace the ignition module in the distributor with a new genuine GM part ($35). This part is the weakest link of 70s/80s GM cars in my opinion. If it dies, you're stranded. The car will not start. Just remove the cap and rotor and take out two screws. I always keep a spare in my glovebox and a phillips head screw driver in case one goes out--this has happened to me twice in the 6 years since I've owned about 8 70s/80s GM vehicles.
8. Next time you change the oil, look for the hole in the bottom of the evaporator case. If you still use your A/C, clean this hole out gently with a screwdriver. It becomes plugged with dirt/debris over time and won't let the water drain out of the case. You'll then end up with water on your floor when you turn a corner on a humid day.
I just made a 550-mile round trip in my 76 Eldorado with 51k miles. Car was a blast to drive. Just thought I'd share that I averaged 15.8 mpg with the cruise set at 68 mph and the A/C on about 1/3 of the time.
For an 8.2L V8 with a 3-speed auto, I couldn't believe the mileage! I get about 10 mpg city and almost 16 highway.
I've rebuilt the QJet carb, put in new Delco plugs, wires, cap & rotor, fuelt filter, air filter, fresh oil change, new fuel pump (old one worked fine, but didn't trust it for long trips), new ignition module in distributor (again, replaced preventatively--always keep a spare in my glovebox!), gutted the converter and resonator, set the timing at 8 degrees base instead of 6, and put on a big muffler that sounds great--not too loud or quiet, just right.
A couple of tips from my experience owning two 1976 Eldorados:
1. If you're having problems with your blower turning on while not in "Off" or "Lo", check for a loose connection at the "Auto Relay" on the driver's side of the evaporator case. Clean off the contacts and reattach. If this doesn't work, try a new "Auto Relay". They seem to go bad.
2. Keep the EGR valve and make sure the diaphram moves freely with firm pressure. This will allow you to run at about 8 degrees timing advance with no spark knock on 89 pump gas. This will increase power by about 5% and mileage by about 5% too.
3. Replace the primary choke pull of (vacuum break) on the carb. It's $15 and most of them are shot. This will lead to poor cold driveability as the choke won't open properly. Takes about 30 mins to replace.
4. Rebuild the QJet and make sure to seal the well plugs in the bottom of the float bowl. These start leaking after 30 years, creating long hot-start cranking times and that puff of black smoke on start up. Not to mention, you're wasting the gas that drains through the plugs into the intake. This will also help cold starts. Without resealing these plugs, the float bowl will drain, and you'll have to crank until the bowl is refilled. If my car sits for 3 days, all I need is ONE pump on the pedal to set the choke, and the car starts INSTANTLY. Instant hot starts, too! Rare for an old carbureted car.
5. If you've got a "sagger" in the rear, try filling the compressor on the passenger side to 90 psi. If the shocks air up, they may hold air. If the car sits for a long time, the compressor isn't strong enough to pump them up on its own.
6. If your car has cruise control and the speedo is jiggly/making noise, you probably need a cruise control transducer. This is also the case if, when you set the cruise, the car surges, then coasts. They cost about $120 and can be swapped in about 30 mins. I've owned 3 GM cars where I've had to replace this. If you don't replace it, the transducer will likely freeze, snapping the speedo cable from the trans.
7. For long trips, replace the ignition module in the distributor with a new genuine GM part ($35). This part is the weakest link of 70s/80s GM cars in my opinion. If it dies, you're stranded. The car will not start. Just remove the cap and rotor and take out two screws. I always keep a spare in my glovebox and a phillips head screw driver in case one goes out--this has happened to me twice in the 6 years since I've owned about 8 70s/80s GM vehicles.
8. Next time you change the oil, look for the hole in the bottom of the evaporator case. If you still use your A/C, clean this hole out gently with a screwdriver. It becomes plugged with dirt/debris over time and won't let the water drain out of the case. You'll then end up with water on your floor when you turn a corner on a humid day.