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I have an 85 Spider with a very noisy engine (knocking in the bottom end, low oil pressure and low compression). It's not really drive-able anymore, and I've got everything disconnected and ready to pull (motor and transmission).

I have gone back and forth on what to do - rebuild what I have (not knowing what is wrong at the moment) or just buy a used motor, do some basic rehab on it (seals and valve adjustment) and drop it in. My question is if a later motor (say a Motronic motor) will work with my existing car (with L-Jetronic)? Is there anything I need to watch out for? I haven't found a good donor motor just yet but I want to know what fits before I get too far along.

I know there's probably a chart here somewhere - I just haven't had time to look. Can anyone tell me "yes" or "no"?

Thanks.
 

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Any L-jet ('82-'89) engine can be a bolt-in replacement. The earlier ('82-'84ish) will have a centrifugal VVT, later L-jet ('85ish-'89) have a solenoid activated VVT. Easiest replacement would be one with the same VVT as you have now.

Motronic series ('90-'94) won't be plug-n-play but it could be done.
 

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Discussion Starter #3
Any L-jet ('82-'89) engine can be a bolt-in replacement. The earlier ('82-'84ish) will have a centrifugal VVT, later L-jet ('85ish-'89) have a solenoid activated VVT. Easiest replacement would be one with the same VVT as you have now.

Motronic series ('90-'94) won't be plug-n-play but it could be done.
Thanks for the reply. I assume, by "won't be plug-n-play" you're just talking about the EFI connections and such? I am mostly concerned about the VVT, which on my car is a solenoid and the two flywheel sensors on my L-Jet car. Will these bolt up to the later engine? I'm curious about the later motor because I may have found a good donor. The only thing I'm a little nervous about is that the potential donor IS from a Motronic-era car. I have no problem fitting all my L-Jet parts to a later engine, as long as there are places to bolt everything up. If I had to, I'd even be willing to pull the whole Motronic system out of another car and retrofit my 85. I just don't want to encounter something insurmountable.

Thanks again.
 

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Putting an earlier L-Jet engine with the mechanicall VVT in your car is not an issue. I replaced the engine in my '88 with one from an '82.

The difficulty of a Motronic swap is a good question and one I don't have an answer to. If the heads are the same then you could use the intake manifold from your engine with all of its L-Jet hardware. Additionally, you could probably use your intake cam, the solenoid actuated VVT, and your L-Jet cam cover... if the heads are the same.

I think the decision of whether to rebuild or replace comes down to what you want to do with the car and what the current engine requires. A replacement engine may be less expensive and get the car going again sooner (as long as you know it is a good engine). But now you have another old engine with no baseline to move forward from. If you plan on keeping the car for several years, then a rebuild starts to make more sense. I would tear the current engine down and determine its needs and the cost before proceeding one way or the other.
 

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Everything from your 85 engine will bolt on to a motronic engine. Putting the motronic injection system in your car will give you the full performance of the motronic engine. The downside is if want to keep your a/c and run the motronic you have to find the rarer the hens teeth 1990 crank pulley. This is a one year only pulley thats has a v belt groove for the a/c belt. 91's and later are the poly v belt.
 

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pgman,

spiderjump2 is buying back his rear ended 87 and will be parting it out. Copart said it has 52K miles and is in Texas. Why don't you PM him about the motor? He had the car for 15 years before it was wrecked, so he will know the history perfectly. Go back one page and read "I am fine but I lost the baby". There is a link on page 3 to the Copart listing, so you can see what the wreck looks like right now. The motor would be a "drop in" installation.

Robert
 
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