: 81 deville with a v864 injected 500???



sizanjdf
03-27-06, 03:58 AM
Ive been looking for a local caddy for a while with at least the 368 or larger engine. I finally found one today and started reading up on them. I didnt realize before that the 368 was fuel injected when matched with the v864. I know that the 368 is the baby brother to the 500 and was wondering if you could swap them... maybe use bigger injectors or something and have a v864 500. anybody ever tried this? or someone with more experience with fuel injection might know what all is needed to feed an extra 132 cubic inches?

Bro-Ham
03-27-06, 09:05 AM
Hello,

There was discussion on this forum last fall about doing what you're wondering about. Engine swaps are heavily discussed on this forum although it seems rare when one actually happens.

I have a 1981 V8-6-4 and the technology for the system was not in any way perfect back in 1981 and continues to cause problems for owners today. There was a thread about V8-6-4 problems on this forum as recent as a day or two ago. I would remove the V8-6-4 system right now from my car if it were possilbe to do easily, but I've been told it is not.

If I were you I'd bolt in the new 500 engine and forget about the ancient variable displacement technology that hardly works.

Good luck!

Dave

brougham
03-27-06, 05:33 PM
A lot of people with that engine don't haev any problems with it. But like Bro-Ham said do a search because there are a lot pf posts about it.

davesdeville
03-29-06, 07:04 AM
There's a guy on another forum who was trying to adapt the MD system onto a 500. I haven't heard any updates in awhile. I wouldn't bother with the 368 FI intake and the original computer. If you want FI using a FI 500 intake or even a bulldog along with a newer controller such as a megasquirt would be a better idea.

Series75
03-29-06, 12:19 PM
The f/i system on the MD368 was simply a throttle body with 2 injectors instead of the usual Q-Jet. The MD system involved the solenoid activated valves and was basically a seperate system. In 1980 the 368 had just the f/i but in 1981 it had both the f/i and the MD systems.

I'm not sure of the flow of the f/i 'carb', but I know the ports on the intake manifold were not as large as those on the 500. I guess it could be made to work on a 500, but I'm not sure of the benefits.

I took the 368 (f/i and MD) out of our '82 Series 75 and dropped in a 500 with a Q-Jet. Much better performance and no computer headaches. Just fuel bill headaches....

Dave

Bro-Ham
03-29-06, 12:46 PM
Hi Dave,

I'm making a separate posting about my desire to get rid of the V8-6-4 in my car. If you'd be kind enough to take a look I'd appreciate it much!

Dave T

Bro-Ham
03-29-06, 01:41 PM
Hi Dave, again,

If I got rid of my V8-6-4 and went with a regular 368 or a 425, is there still a computer? What about the climate control which has all the engine diagnostics? I'd prefer a 368 with a carb and even the unloved 425 would be good for me too. Ape Man has been nice to share some ideas on this too.

Dave T

Series75
03-29-06, 02:10 PM
Dave,

You should be able disable the MD 'feature' by snipping a wire that goes to the tranny. It needs a signal from the tranny that it's in 3rd gear to think about working. You'd still have the f/i and you could leave the solenoids in place. This is how ours was when we bought it. Even like that, the f/i would mess up from time to time and we had to replace the ECU once.

When we did the swap I attacked the wiring harness since I was doing away with the a/c as well. Not sure how complicated it would be to switch to a regular carb (either on a 368 or 425) and keep all the computers happy. If you do find a 425, save the passenger side exhaust manifold since it fits the 500 and has the indentation for #1 cylinder.

Dave
http://www.mindspring.com/~dburden/engine_swap.html

sizanjdf
03-29-06, 03:49 PM
well I test drove the car and it was a total disapointment it had less power even than my 86 with the 307. I was disapointed with the fuel injection and I doubt the MD was working. I should have bought the 91 a few months back with the 350 in it for 1700 bucks, but I was broke and stupid. Now I will suffer not having the car I want.

Series75
03-29-06, 04:51 PM
If the rest of the car is in good shape, and you feel like doing a transplant, it might still be worth it. The 500 will basically drop right in and any parts you need are already on the car. Like I said, though, not sure how the climate control system will work since we skipped that step on our car.

Dave

The Ape Man
03-29-06, 07:10 PM
To convert from 8/6/4 to carbonated engine, leave the ecm in place to operate the AC. Just remove the esteemed Czech engine lamp. Same for RWD HT-4100 cars. Pretty much the same exact system without the modulated displacement.

Bro-Ham
03-30-06, 01:26 AM
Hi Ape,

What are your thoughts on keeping the current engine but cutting the wire to the transmission as had been done in 75's car with the V8-6-4? My engine seems to run fine until the computer (compuker!) starts to interfere. My 79 with a carb runs perfectly every time and I only can dream of the 81 doing the same.

Dave

The Ape Man
03-30-06, 05:37 PM
Try it and see. The info is on this board. All it takes are the right search words.
A quick check can be done by simply pulling out the electrical connector located on the driver's side of the transmission. Note: You will lose the back-up lamps with the connector unplugged.

Bro-Ham
03-30-06, 07:21 PM
Hi Ape Man,

As always, thanks for guiding me! Is it possible to convert my V8-6-4 FI car to a carb?

Dave

The Ape Man
03-31-06, 04:32 AM
Yes, but it is more work than repairing it.