george glover
New Member
i have an 81 imp with efi n want to convert to carb, can anyone help me with what needs to be done? tks
efi to carb
- Thread starter george glover
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intake if you go to a 4v, carb obviously, linkage, mechanical fuel pump 1st come to mind.
you will lose the dash computer's mpg function.
i had an 81 that we put a 4v on, but it had already been converted to a 2v.
if you do dual exh the gas tank will need to be shifted over ( easy) and a longer rear brake hose will be needed too.
and check what what your axle gear is, mine was a 2.24 sure grip which we changed to a 3.23
im sure there is more ive forgotten, others can add their knowledge.....
you will lose the dash computer's mpg function.
i had an 81 that we put a 4v on, but it had already been converted to a 2v.
if you do dual exh the gas tank will need to be shifted over ( easy) and a longer rear brake hose will be needed too.
and check what what your axle gear is, mine was a 2.24 sure grip which we changed to a 3.23
im sure there is more ive forgotten, others can add their knowledge.....
george glover
New Member
yup guys are trying to help but they did this swap so long ago they forgot all of what they did tks
Justin Plant
Well-Known Member
Why not use a FI Tech FI system? Holley Sniper offers some options too. It would probably cost about the same only the reliability would be better. 2 BBL and 4 BBL styles are offered by each company. You've already got the return lines and presumably an in tank pump too. Just a thought.
The factory conversion kit from Chrysler included a complete fuel system, from the tank to the engine, which was basically the same as a Dodge Mirada or the similar Cordoba.
Other than unobtainium parts, the one observed issue with the Imperial EFI was that the mass air flow sensor was placed in the air cleaner snorkel. With the engine running, and the air cleaner/fuel plate top removed, no air flow through the snorkel and the engine automatically died . . . usually to a "What did YOU do?" reaction. By the same token, if the air cleaner band clamp was not holding the top on the fuel plate securely with no leaks, that little "leak" would affect the air flow through the snorkel and cause rough running or similar.
One year at Mopar Nats, we were seeing what was in the hotel parking lot. One guy had a white Imperial there, which he had just bought. His buddy at the Chrysler dealer alerted him to it, on the back row of the used car lot's "wholesale" area. The grand-daughter of the original owner had traded it in, as it was not running well and nobody knew what to do to make it better. The guy knew of the air cleaner issue, he related, so he made a "cheap deal" and drove the car home. Fixing the band clamp's position later on. It had about 100K on it and he said it ran well. Of course, 100K with a 2.2 rear axle ratio would be more like 75K miles with a 2.71 rear axle ratio, possibly.
From what I figured out, that particular EFI system was a quick and relatively inexpensive way to offer (class needed) EFI. It was more self-contained, with the bulk of the mechanism on the "air cleaner fuel plate". This tended to reduce complexity and the number of unique parts, too.
Considering that Holley Sniper EFI has 2bbl self-learning EFI kits now, that might be the path of least resistance. I suspect the throttle body of the Imperial system uses the 318 Carter BBD bolt pattern? If so, then there's a "car, not Jeep" Sniper EFI kit for it. Not sure if the Imperial EFI distributor might need to be replaced, though. OR, if a 4bbl was desired, then the one of the several variations of self-learning EFI kits from Holley?
I'm not sure where the "MPG" reading came from or how it was derived on the Imperial EFI system, but that might be a minor consideration? Perhaps there is a MasterTech video that explains how it all works?
One other consideration might be one of the Holley factory OEM 2bbl TBI kits like were on pre-Magnum pickup trucks? Which would need a matching intake manifold . . . and possibly some other interfaces, too. FWIW
In the current time, those Imperials are classy cars and deserve something more than a more-mundane carburetor under the hood.
Just some thoughts and observations,
CBODY67
Other than unobtainium parts, the one observed issue with the Imperial EFI was that the mass air flow sensor was placed in the air cleaner snorkel. With the engine running, and the air cleaner/fuel plate top removed, no air flow through the snorkel and the engine automatically died . . . usually to a "What did YOU do?" reaction. By the same token, if the air cleaner band clamp was not holding the top on the fuel plate securely with no leaks, that little "leak" would affect the air flow through the snorkel and cause rough running or similar.
One year at Mopar Nats, we were seeing what was in the hotel parking lot. One guy had a white Imperial there, which he had just bought. His buddy at the Chrysler dealer alerted him to it, on the back row of the used car lot's "wholesale" area. The grand-daughter of the original owner had traded it in, as it was not running well and nobody knew what to do to make it better. The guy knew of the air cleaner issue, he related, so he made a "cheap deal" and drove the car home. Fixing the band clamp's position later on. It had about 100K on it and he said it ran well. Of course, 100K with a 2.2 rear axle ratio would be more like 75K miles with a 2.71 rear axle ratio, possibly.
From what I figured out, that particular EFI system was a quick and relatively inexpensive way to offer (class needed) EFI. It was more self-contained, with the bulk of the mechanism on the "air cleaner fuel plate". This tended to reduce complexity and the number of unique parts, too.
Considering that Holley Sniper EFI has 2bbl self-learning EFI kits now, that might be the path of least resistance. I suspect the throttle body of the Imperial system uses the 318 Carter BBD bolt pattern? If so, then there's a "car, not Jeep" Sniper EFI kit for it. Not sure if the Imperial EFI distributor might need to be replaced, though. OR, if a 4bbl was desired, then the one of the several variations of self-learning EFI kits from Holley?
I'm not sure where the "MPG" reading came from or how it was derived on the Imperial EFI system, but that might be a minor consideration? Perhaps there is a MasterTech video that explains how it all works?
One other consideration might be one of the Holley factory OEM 2bbl TBI kits like were on pre-Magnum pickup trucks? Which would need a matching intake manifold . . . and possibly some other interfaces, too. FWIW
In the current time, those Imperials are classy cars and deserve something more than a more-mundane carburetor under the hood.
Just some thoughts and observations,
CBODY67
george glover
New Member
tks
Here's a link to the factory conversion manual:
george glover
New Member
Rustyrodknocker
Senior Member
A question I would ask is, do these engines have the accommodations to add a mechanical fuel pump?
If that can be done, that is the way I would go.
I have had fi to carb conversions and used fuel pressure regulators with poor results. I think it's too much of a step down. Trying regulate down to 10 percent of normal pressure. Mine tended to run rich in town and was fine on the hiway.
That was a gm block and it was not drilled for a fuel pump pushrod and may not of had the eccentric on the cam to run it.
If the imperials cant be swapped to manual pumps I would reccomend an electric clickity clack style pump of good quality, mounted at the rear of the car. These are designed for carburetor pressures.
Ignition wise, a regular small block electronic distributor and the matching box or a gm hei module like I use.
Then ofcourse the manifold and carb.
For my obligatory offering of derailing your intentions, but only after I answered the original question to the best of my ability...
The carb I would reccomend would be the one mounted on a strong running short deck big block. To which you can leave on said engine and drop it in the Imp. That way the distributor is easy to get too amongst other logical reasons.
As far as no you don't want a carb.
My version 1 is go pull a late model magnum series 360 out of a donor truck.
Or a cheap 5.7 hemi in version 2.
I dont know the ins and outs of the best ecu solution. Maybe a megasquirt or some other aftermarket.
If that can be done, that is the way I would go.
I have had fi to carb conversions and used fuel pressure regulators with poor results. I think it's too much of a step down. Trying regulate down to 10 percent of normal pressure. Mine tended to run rich in town and was fine on the hiway.
That was a gm block and it was not drilled for a fuel pump pushrod and may not of had the eccentric on the cam to run it.
If the imperials cant be swapped to manual pumps I would reccomend an electric clickity clack style pump of good quality, mounted at the rear of the car. These are designed for carburetor pressures.
Ignition wise, a regular small block electronic distributor and the matching box or a gm hei module like I use.
Then ofcourse the manifold and carb.
For my obligatory offering of derailing your intentions, but only after I answered the original question to the best of my ability...
The carb I would reccomend would be the one mounted on a strong running short deck big block. To which you can leave on said engine and drop it in the Imp. That way the distributor is easy to get too amongst other logical reasons.
As far as no you don't want a carb.
My version 1 is go pull a late model magnum series 360 out of a donor truck.
Or a cheap 5.7 hemi in version 2.
I dont know the ins and outs of the best ecu solution. Maybe a megasquirt or some other aftermarket.
george glover
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I had a retrofit complete in the OEM box...it filled the back of a pickup truck. Insane mess to change over and it came with a different digital dash cluster too.
I did not install it. I sold it to someone who did an install for a customer.
If you do change it out keep what you remove....somebody else will be needing it!
I did not install it. I sold it to someone who did an install for a customer.
If you do change it out keep what you remove....somebody else will be needing it!
george glover
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it will be up for grabbs
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george glover
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