81 Imperial - Carb/ FI swap?

[Turbodave]

My wife's Uncle has a good condition 81 Imperial, the car has been sitting for the last few years because he's had troube getting it to run right and it's been through a bunch of mechanics. The original fuel injection system is long gone and a 2bbl carb is currently in it's place.

I offered to help him get it running better, and would like it to have the driveability of a modern efi car. Performance isn't a huge concern as I think any of the options I've got in mind would be better than the 2bbl.

Looking to keep the cost of the conversion to under $1,000

I'm thinking a TBI setup will work fine for this car so I've got 2 possible plans let me know what you think.

Plan A - Piggyback the electronics from a late 80's TBI ram truck and grab all the components from that vehicle

Plan B - Run a holley Pro-jection setup with feedback

[Clay]

run 92+ magnum MPFI on it.

get a complete intake, all the wiring and computer.

Intake bolts on different, but can be made to work fairly easily.

[88_pacifica]

...would like it to have the driveability of a modern efi car. Performance isn't a huge concern as I think any of the options I've got in mind would be better than the 2bbl.

Is the body in THAT good of shape to warrant that much effort? Are they just REALLY attached to this thing? Personally since it has the smog-era heads, I think getting a different OEM style F/I system to "sync-up" is going to be a MAJOR beotch because of chamber diff, comp ratio, emissions, etc, unless it's adjustable....

Is it a DD for short distances(groceries, work, etc) or for major roadtrips? Is this a 318(I'm assuming) with the poopy OEM style emissions crap that was a nightmare(name is escaping me right now)? Why not get a totally rebuilt crab and start from scratch. Maybe $250 tops dialed in except for minor tweaking? I would do this if the life of the car or the long distance needs are minimal.

Now, if you're doing it just to do it though.... More power to you. I'm lazy.

[Clay]

if it has crap smog heads, then I would just do a magnum motor head/intake swap. Good heads, good MPI, good to go!

[raccoon]

wow a RWD j-body! any photos of it?

[banger68]

run 92+ magnum MPFI on it.

get a complete intake, all the wiring and computer.

Intake bolts on different, but can be made to work fairly easily.

You would have to swap the heads too. The bolt pattern is different on the intake. The magnum heads are much better anyways. Can you use the stock computer without the tone ring? I was considering this same swap in my 83 Cordoba.

[BadAssPerformance]

Are you going to get to borrow it so we can cruise it at the Moapr Nats?

[Turbodave]

Is the body in THAT good of shape to warrant that much effort? Are they just REALLY attached to this thing? Personally since it has the smog-era heads, I think getting a different OEM style F/I system to "sync-up" is going to be a MAJOR beotch because of chamber diff, comp ratio, emissions, etc, unless it's adjustable....

Is it a DD for short distances(groceries, work, etc) or for major roadtrips? Is this a 318(I'm assuming) with the poopy OEM style emissions crap that was a nightmare(name is escaping me right now)? Why not get a totally rebuilt crab and start from scratch. Maybe $250 tops dialed in except for minor tweaking? I would do this if the life of the car or the long distance needs are minimal.

Now, if you're doing it just to do it though.... More power to you. I'm lazy.

It's in good shape from what I remember, it's been a few years since I've seen the car. It's all black and looks just like a Grand National, only different...

I've thought about doing a Magnum swap, but I'm not sure about the hood clearance needed with the tall magnum intake.

It's a 318 with all the lean burn junk on it. Originally it had an factory fuel injection setup, but that was prone to failures so it was converted to a carb, it hasn't run right since.

I could go the rebuilt carb route, it may not even need that, but I know the car has been many mechanic's nightmare over the years and my carb skills are limited.

The TBI 318 trucks I've had were always excellent runners (crappy performance however), and I think if I got this car to run like that it would be exactly what he wants, just being able to get it, fire it up and go without worries about it stalling at lights or hard starts when hot etc...

[Clay]

You would have to swap the heads too. The bolt pattern is different on the intake. The magnum heads are much better anyways. Can you use the stock computer without the tone ring? I was considering this same swap in my 83 Cordoba.

no you dont.

2 options.

1. You can redrill the new intake to match the old heads.

2. You can redrill the heads to match the new intake.

Option 2 is done more often than you think. There are actually jigs out that make the job very easy.

and tone ring?????? why do you need a tone ring? your only using the computer for the FI, or are you talking about the HEP in the distributor?

[88_pacifica]

It's in good shape from what I remember, it's been a few years since I've seen the car. It's all black and looks just like a Grand National, only different...

Ha.. riiggghhhhhhtttttt....

I could go the rebuilt carb route, it may not even need that, but I know the car has been many mechanic's nightmare over the years and my carb skills are limited.

The TBI 318 trucks I've had were always excellent runners (crappy performance however), and I think if I got this car to run like that it would be exactly what he wants, just being able to get it, fire it up and go without worries about it stalling at lights or hard starts when hot etc...

TBI would be very cool and faitly straightforward except for wiring. The heads won't be AS big of an issue since a TBI is basically a "precise carb." I would think a professionally rebuilt carb set at '78 factory specs though would be the hot ticket. If you get a rebuilt one with those settings(same poopy settings except torquey'er(sp)). That should even have the necessary crap to make it run right and if run like grandpa Jones, then the mileage will be about the same within a 1 or 2 mpg...

[JDAWG]

didnt those cars orgionally have the lean burn crap? Could you get a tb and get the conversion kit from MP that takes the lean burn crap away?

edit- or maybe the lean burns were carb? i cant remember

[turbovanman²]

I would pick up the MPFI setup, I have one upstairs, cost me $100 for all the hardware.

Tone-ring? the dist drops in place of the old one, thats where they house the HEP,

[guyd_15]

I remember working on those way back when, even Ma Mopar thought the fuel injection was whacked out. It ended up being a sealing problem with the top of the air cleaner housing.

[Spraynlog]

I'd replace the lean burn nightmare with an 'Orange Box' ecu and an Accel super coil. Then install an Edelbrock Performer with a 600 cfm carb. Add in some exhaust clean up, and it'll have more poop than you might think.

I'm not too sure about the wiring on the EFI it had, but another idea would be to use a DUI distributor. All you need is one 12v 'key on' power source and you got yourself a strong ignition.

[banger68]

no you dont.

2 options.

1. You can redrill the new intake to match the old heads.

2. You can redrill the heads to match the new intake.

Option 2 is done more often than you think. There are actually jigs out that make the job very easy.

and tone ring?????? why do you need a tone ring? your only using the computer for the FI, or are you talking about the HEP in the distributor?

Yeah, I've heard about that jig. There is a guy that rents one. But the magnum heads are much better than the original. Go to the trouble swapping the MPI take the heads too. What I meant was I thought there was a crank sensor.

[banger68]

My goof. The crank sensor gets it's reading off the flexplate or flywheel.

[banger68]

didnt those cars orgionally have the lean burn crap? Could you get a tb and get the conversion kit from MP that takes the lean burn crap away?

edit- or maybe the lean burns were carb? i cant remember

The lean burn is the "computer", carb, and the distributor. The fuel injection on these cars was even more troublesome.

[moparzrule]

I'd replace the lean burn nightmare with an 'Orange Box' ecu and an Accel super coil. Then install an Edelbrock Performer with a 600 cfm carb. Add in some exhaust clean up, and it'll have more poop than you might think.

+1 to this. I had a 77 Chrysler newport with a 440 lean burn, but it was carbed and had a thermoquad. Bought the Mopar performance conversion kit, comes with the orange box, ballast resistor, and the distributor with cap+rotor and vacuum advance for $215 from Jeg's. It's meant to convert old points cars to electronic ignition, but the same thing needs done with the lean burn so it's a perfect kit.
Do that and put that intake and carb on, should have plenty of pep after that. And tuning an edelbrock is a snap even if you don't know what you are doing. For the most part the 600 is tuned very well right out of the box and good enough left alone for most applications.

[The Pope]

you need the performer 4 barrel carb for all of the factory BS to bolt and screw to. Then get a used TBI pro jection on ebay and a wide band sensor.

The 81 Imperial is a sweet car, the nicest of the old V8s. The car even bigger and heavier was great in NASCAR because it really cut through the air, the body wasn't just for looks. My dads new 81 got 31 MPG on the highway, always averaged better than 30 running 65 MPH. If the car is really nice consider buying a junk yard 360 magnum complete with harness and rebuild it with 9.0 pistons and a 4.00" crank. Then run 24 lb injectors and a MP FI cam. Cool Mopar.

Rob

[glhs0426]

I drove an '81 Imperial for several years. I converted the FI to carb by purchasing an '83 Cordoba from the police auction in order to get tank, wiring, engine harness, carb and intake. Next was the "orange box" kit, carb rebuild, and a new exhaust w/o cats. Total investment about $400. I had to recurve the distributor because the advance curve was not optimum for a heavy car with 2.24 gears. The thing ran great and returned 25+ @ 75mph! Routine maintenance and the car never had any problems for more than three years.