1984 Cadillac Eldorado

[simp35]

right now I have a HT4100 in the car. but would like to know if I can put a 350 engine, or what would be the best other then the HT4100 
I also heard I can put a 4.5L but don't know what car to get one from

[Rusty Shepherd CLC 6397]

From what I have learned on this board, you can replace the HT4100 with a 350, but it is a very difficult job particularly since some of the 350's are carbureted and the electronics of the fuel injected ones don't correspond to those of the HT4100. The 4.5 and 4.9 won't work because they were built only for transverse, not longitudinal installation.

[bcroe]

You certainly can add a 79/80 carb small block engine without much trouble.  My choice would be an Olds 403, 350, or 5L, depending on the performance you want.  These engines need a flywheel from a 79-85 E car (Riv/Toro) with an Olds V8.  A parts 79 Toro/Riv will give you all the parts you need & a 350. 

Adding some kind of fuel injected engine would mean transfering over all the computer controls with it, which may extend to other parts of the car.  You may also find your current engine computer affects other than engine functions as well.  Bruce Roe  CLC # 14630

[Otto Skorzeny]

Do a search of this forum for information about what to do with your 4100.

A recent thread describes the Goodwrench HT4100 replacement engine. This incorporates GM's improvements and corrections to the original design. Try to find one of those. The threads describe the differences and how to identify one.

If you're hoping for a bolt-in replacement engine of conventional design, none exists.

[TJ Hopland]

Only way I would take on a swap like that is with a donor car.   The 4100 was different than any other motor so you will have to change all sorts of stuff which wont be a big deal if you have a whole car but if you have to track down and buy individually would probably cost you more than you could imagine.   Unless you are into total fabrication and custom work you will have to use a motor that was an option in one of these cars.  The FWD configuration has unique mounts,  oil pan, and exhaust manifolds to clear the drive train.  Oldsmobile V8's (gas and diesel) were used during the entire run of this body style which was 79-85.  Buick 3.8 and 4.1 v6 (even turbo 3.8's) were used most years.  80 and 81 used the Cadillac 368 which was based on the 472 / 500 /425 which opens up all sorts crazy performance options if thats what you are after.    There was never a chevy motor made for this configuration.   Its the Cad Eldo, Seville (with the funny trunk), Riv, and Toro you would be looking for.   Even a diesel would give you the parts you need to swap in a Olds gas engine.

[76eldo]

TJ is 100% correct.

I would look for a 1980 Eldorado for all of the needed parts, and you can use the 368 cast iron engine.  With the proper parts, it's a bolt in.

Here's the best website for the exact info you are looking for:

http://radar58.com/eldo/swap.html

Read the whole page, it will make your head spin...

Brian

[bcroe]

The beauty of the FWD 79-85 transmission, is that it will accept any engine used in those years such as 5L, 350, 368, turbo charged V6, or 4.1.  AND it will accept any front OR rear drive engine from the SAME  families, such as 403/455 Olds, 472/500/425 Cad, or diesel.  The same engine will work FWD or RWD, I have converted them both ways.  But the FWD needs the 79/85 FWD flywheel, exhaust manifolds, oil system including pan, pickup, & pump, and some other details.  So a parts car with an engine from the right family is good advice.  Changing to a carb mainly means changing the tank pickup or just the whole tank (parts car again) to eliminate the electric fuel pump. 

Getting a new engine properly fuel injected is probably a bigger project than the actual engine swap, these need some expertise.  My 79 Eldo has a 403 with original 350 fuel injection, but the ECU has been modified for the larger engine. 

A heavier engine will beg for a step larger torsion bars.  Bruce Roe  CLC # 14630

[simp35]

Thinks for the help it's new to me an now I ask this because I just got off the phone with The staff at remanufactured.com
an was told that  they had a swap for my car. I believe it was a 4.1 to4.5 273 V8 Custom upgrade 85-86 4.5 liter 'FWD or RWD as long as it sits front to back, Block #864, Head #556, 558, HSC heads, Eldorado & Seville only. Not transverse engine. or HT 4500 Cadillac Transverse one of the to but Im still talking to them an once I know more I'll be sure to let u know. but my ? is have anyone heard about this or had it done

[TJ Hopland]

I have heard of the 4100 to 4.5 conversion.  The front to back (longitudinal) vs transverse are the key differences.  The 4.5 and 4.9 were never made for longitudinal but I guess the 4.5 was not much different than the 4100 so the internals can be swapped.  The 4.9 had more changes so I guess that wont fit in the 4100 block.

[simp35]

thanks TJ

[John Paul]

I would try to find an 307 olds set up from a riviera or tornado.. IMHO