1984 Eldo Biarritz 4.1 V8 Engine

[James Landi]

Eric...TJ... electronics do run with the 260 Olds ...fuel mileage included. I've been there (260 Olds conversion) and done that .,6 years ago, I.know it works  just fine  James.

[79 Eldorado]

I'm just curious why nobody has mentioned the Olds 307. It seems like the 307 was used in basically everything Olds powered from ~1981 through whenever they stopped using it in the Cadillac Brougham (Including the Riv and the Toronado from 1980-1985). As I recall the 260 was not highly regarded but I don't remember what the concern was and how easily it could be overcome.

Regarding donor vehicles an E-Body is ideal but it seems like any vehicle with Oldsmobile compatible brackets will work. Using something other than an E-Body would require motor mounts and the shallow front oil pan used on the E-Body. The AC line could be re-made because those would likely be unique. Bruce pointed out exhaust manifolds. There is a place manufacturing Olds exhaust manifolds. They have one for the passenger side with a single outlet. The E-Body is pretty unique on that side but I don't remember what it's trying to clear HVAC module? I can go look. What became a crossover on later Olds with single exhaust was more of a Y on the E-Body at least in 1979.

Am I missing any other hard to source parts? Again E-Body ideal but opening up the search would make it easier to find at least a donor motor. I recently looked to see if motor mounts were available new... I did see at least one seemingly incorrect listing. I didn't check for an oil pan.

Scott
PS: My preference would be either the 403 or the 350 but just following on the lines of those might be harder to find.

[Eric DeVirgilis CLC# 8621]

Eric...TJ... electronics do run with the 260 Olds ...fuel mileage included. I've been there (260 Olds conversion) and done that .,6 years ago, I.know it works  just fine  James.

You were able to keep Fuel Data panel in operation with a carb engine?   

Out of curiosity, do all the self diagnostic functions through Climate Control panel still work, ie: when depressing the OFF & WARMER buttons?

[TJ Hopland]

I do recall James' story about the 260 with a carb and the 4100 dizzy still working.   What I was wondering is if you could go a step further and also put the throttle body injection on. 

I would think in his case the diagnostics would work the same.  All he would have had to be missing was the injectors and possibly what ever the idle control method was.  It is a little odd that the computer wasn't angry that the injectors were missing but I guess I never tried running an engine with them disconnected so maybe in the design meeting when the computer nerd said we need a trouble code for that everyone else in the room sad why?  You will know if they are not connected because it won't run.   With multiport there are codes for injectors but maybe when there was 2 it just wasn't needed.

Thinking more about it I also wonder how it would not be angry that a lot of the emissions stuff was missing too.  I'm assuming he didn't re install things like the EGR control solenoid to the Olds motor and the diverter valve on the smog pump.  Those things would for sure have codes because they were required to for emissions.   Hopefully he can fill us in on those details. 

I didn't recall in James' story that the trip computer still worked and seemed to be useful.  That is interesting but I guess shows how not especially smart it must have been.  I guess I never really thought about what data it was using to calculate economy.   Apparently its just using manifold pressure and rpm which I guess makes sense.  It takes those readings and then some sort of calibration number burned into the prom chip and does its calculation.  RPM is RPM and the manifold pressure would give you an idea of the load so that would be all you really need to make a good guess.  Manifold pressure would have had to been still hooked up and working because that signal is used to adjust the timing just like it did with the vacuum can on the old dizzy.

A 307 would be an option I was just saying 260 because I wondered if the displacement being close to the 4100 would let the EFI system work reasonably well.   I don't think you would have a good a chance with a 307 and I suspect a 350 would be a disaster without the ability to create a completely new tune in the computer as well as change injectors and other things like maybe even the size of the throttle body.   All possible since the trucks used the same basic system on 260-454 motors but just 10 more things you would have to source and figure out on top of the 100 you already had on the list.

I don't think there was really anything wrong with the 260.  I think it was actually the best of the bunch, the Chev and Pontiac versions seemed to be a lot worse.   I think the big reason it just never got anywhere is it for sure wasn't any smaller physically than the 350 or 403 (307 came later) and I don't think it was any lighter so it really didn't gain you anything.  IF you could keep your foot out of it you could likely get the same MPG with the 350 or even 403 thanks to the Quadrajet but when and if you needed more power you had it with those engines.   

All those downsized engines including the Cad 368 were really not efficient for their size and weight.  They all had pretty tiny valves to accommodate the small bores because they all kept the 305/5.0 ish or even 350/5.7 strokes (or 472/425 in the case of the Cad).  That just isn't a combo for a good breathing engine which was an extra problem trying to control emissions.       

[JerRita]

Despite the negative comments I'll give you a positive one I have 3 of these a 84 Brougham D'elegance, 84 Eldorado H and E convertible and an 85  Seville D'elegance roadster. The brougham has over 100K on the original motor, the Seville is the upgraded motor and the convertible I got for a song and rebuilt the motor to the new specs. Great cars to cruise around town. I don't drive aggressively and haven't had any major issues, fingers crossed. JeRita   

[TJ Hopland]

I don't know what it is about the above photo of the Seville but that specific photo really captures the love it or hate it aspect of those cars.    Maybe its the angle?  You don't often see a shot fairly square from the side like that.  Maybe its the colors and the background?   

I was hoping James would be back with more details about the electronics part of his swap.  I was working on a TBI system yesterday thinking what if and noticed that I forgot about the Throttle Position Sensor which he would have been missing unless he was using an 80's carb not native to a 260.  You need the TPS for the fuel part but I suppose maybe its not needed for timing.  I would guess that the timing signal would primarily come from MAP and TACH but a missing TPS signal like the rest I mentioned you would really think would throw a check engine light and throw the computer into a fault mode where its going to do things like run fixed timing.   

[79 Eldorado]

TJ,
The Cadillac may have used a more sophisticated fuel economy algorithm but I still remember the first fuel economy gauge I ever saw. It was a mechanical needle and I think it was in an 80's B-Body. I asked a colleague and they told me it worked on vacuum only. It was an instant-only with no averaging. It's been a very long time since I saw it.

If you are looking for a vote on the polarizing Seville design I would just say IMO it would be a PERFECT donor car for the engine/brackets/AC..... I've seen other threads on that specific topic so no sense getting off the track.

Scott

[Eric DeVirgilis CLC# 8621]

Fuel economy gauge is completely different than the mileage display used in Cadillac which used engine data input to make mileage calculations.

I would love to see a working MPG display on a car whose engine was replaced with a carburetor engine. HT4100 MPG display had readouts for instant/average economy (the latter figure displayed as a decimal), fuel used and range. I can't see how this could work without the fuel consumption being metered in some way.

Although not mentioned in the owner's manual, I discovered that depressing the RESET button with the RANGE displayed, the display would read the number of gallons in the tank (displayed as a decimal). 

[TJ Hopland]

If GM didn't change their TBI systems in later years disconnecting an injector doesn't seem to bother them, no check engine light or anything.  I found that out today trying to keep a truck alive.  Its a long story as to why I'm running on a single injector now but it looks like the truck will live to haul garbage around the property for a while longer.   I do really like the TBI systems and some GM engines.  This truck kinda like the knight in Monty Python,  its pretty much just a torso but it keeps screaming 'come back and fight'.   

[James Landi]

The 4100's ECM has a "soft fail" mode, so that when we substituted the Olds 260 and dropped in the 4100 distributor, all systems were "go" - we reconnected the temperature ecm plug ( and, of course the distributor plug), but as mentioned above, nothing having to do with anti pollution devices-- if you're wondering how the ecm handled fuel economy with some of its functioning disconnected, I calculated that with the 260, I lost an average of 1 mpg but had the peace- of- mind that Mrs. Landi and I would not have to ride home in a rental, while the 4100 ignominiously dropped dead somewhere on interstate 95. And you're correct about the mileage/fuel economy digital display-- it is, in fact, connected to the engine through a vacuum hose-- I was both very happy it still worked, and disappointed to learn that I had assumed a much more sophisticated and accurate engineering design stunt. ALL of the automatic air conditioning controls fully functioned after the change. The 260 pulls the Biarritz convertible (250 lbs heavier than the Eldo coupe) just fine... and as far as the ride quality with the heavier iron lady in the front end, the suspension did just fine.  I always add, at this point, that having owned four of these misbegotten 4100's, I had an Eldorado coupe that I purchased in the early 90's with 58k miles, and it ran until it reached 315,000 miles-and died in 2013.  I have absolutely no idea why this happened and the other 3 4100's developed "death" rattles after 100K.   I feel that you can get some decent service out of the 4100's if you don't use them for extensive highway travel... that's when they fail, I could go into detail about getting the panicky, sinking feeling, but I won't ruin your weekend.-- Happy day, and be of good cheer,  James