: 1987 Deville 4.1 to 4.9 Conversion



Edahall
08-12-12, 09:05 PM
This car was the last year that the infamous HT4100 was used. It's got 270k miles on the clock and everything on the car (paint, interior, transmission) is still in good condition except the engine. The engine has had a noisy valve train for a long time but lately, it has been getting progressively worse to the point that everybody could hear it coming from several blocks away. Also, the rated 125 hp was more like 50 hp. The engine would struggle in 2nd gear with the pedal through the metal going up Snoqualmie pass and passed by semi's that were carrying a full load. By the time you got to the top of the hill, 25 mph was as fast as she would go. We did open up the valve covers to inspect the rocker arm support fixtures for cracks and they were fine. So most likely, the camshaft and cams were wiped out. Also, average fuel economy had dropped down to 12 mpg. Even my 1990 3/4 ton Suburban could actually do better than this.

Anyways, long story short, we were given a 4.9 out of a 1992 Seville with 80k miles on it. The decision has been made to put this engine in place of the 4.1. The plan of action is the following:

1. Block off all the injector ports on the 4.9.
2. Bolt down the 4.1 throttle body to the 4.9 intake manifold
3. Transfer all the accessories over to the 4.9
4. Use 350 Chevy injectors
5. Bolt the stainless steel 4.1 exhaust manifold onto the 4.9
6. Use the 4.1 distributor
7. Modify exhaust system to have 2 glass packs in series and replace the back muffler with a chambered muffler.

Replace this
http://img.photobucket.com/albums/v48/rhedahl/P1030093.jpg

With this 4.9
http://img.photobucket.com/albums/v48/rhedahl/P1030098.jpg

dennis93coupe
08-13-12, 01:35 AM
I would try to find the alternator brackets and all other accessories from the 4.9L and use them instead. The tensioner, idler, brackets from a Deville are plentiful in junkyards. You won't need the AIR pump, 4.9's didn't have them, and I don't think there would be an advantage to having one on there. The Seville's had 2 O2 sensors, the Deville of your era had only one O2 sensor. I don't know how the 4.1 manifolds work on the 4.9, here again I would look for a pair from a 91-93 4.9 at the junkyard. And grab the crossover exhaust pipe also. You might be able to use the distributor that is in the 4.9 instead of using the 4.1. You will have a better oil pump in the 4.9 and the gear on the distributor should be in better shape, I'd leave it in there. If you do anything to the 4.9 before you drop it in, replace the valve cover gaskets. Good luck and anxious to see how it turns out.

ehall
08-13-12, 03:21 AM
You've done this before, IIRC. Also, I'm sure you already read through my conversion but here's a link (http://www.cadillacforums.com/forums/ht4100-4-1-4-5-4/128447-im-going-try-4-1-4-a.html) anyway



1. Block off all the injector ports on the 4.9.
I thought long time about doing that and experimented with some options but eventually decided to use the 4.5 manifold for simplicity. One thing I remember for some reason is the PFI valve covers are different from the TBI valve covers, and they are setup for different accessory mounts, I dont remember if its important it just sticks with me.


2. Bolt down the 4.1 throttle body to the 4.9 intake manifold
Should be no problem


3. Transfer all the accessories over to the 4.9
I had to use the 4.9 upper brackets. The accessory bosses on the 4.5 TBI manifold were different and will be different for the 4.9 too. Also the alternator in the 4.5/4.9 is a CS-144 instead of the SI-17 that was in the 4.1, and that has a different bolt pattern on the back, and a different wiring connector too. You might be able to keep the old brackets but I went ahead and used the 4.9 brackets and alternator, with a wiring adapter, since this lets me use CS-144 alternators instead of the old SI-17 alternators.

Also the smog pump setup will not perform any kind of functional purpose on a 4.9 engine since the block does not have the ports for the exhaust gasses. It will just be dead weight, a useless part that can only cost money, etc.

Rest of it should be straightforward


4. Use 350 Chevy injectors
Do you mean 305 injectors? The 4.9 is about 299 CI, so 305 TBI injectors are pretty close. Even those are rich at cold start. 350 injectors will probably flood it out.


5. Bolt the stainless steel 4.1 exhaust manifold onto the 4.9
Yup same port sizes.


6. Use the 4.1 distributor
Yup keep it simple--some of the wiring changed for the 4.9 distributors


edited to fix a couple of comments

Edahall
08-13-12, 02:13 PM
Engine yanked out! Bye Bye HT4100. Anyone want it? Might be good for a riding lawn mower.
http://img.photobucket.com/albums/v48/rhedahl/P1030096-001.jpg

I got the engine bay pressure washed. It was a terrible mess from all the oil that the HT4100 leaked out.
http://img.photobucket.com/albums/v48/rhedahl/P1030102.jpg

Instead of switching distributors, I took some of the guts from the 4.1 distributor and put it into the 4.9 distributor. I left those 2 connectors (at the bottom of the picture) disconnected because the 4.1 doesn't use those. I hope it'll work.
http://img.photobucket.com/albums/v48/rhedahl/P1030106.jpg

ehall
08-13-12, 02:36 PM
If you look at the aftermarket HEI parts, you'll see they are different for 4.1 and 4.9. From what I remember, wiring from the coil was different at the connector. It was something like yellow and red were reversed, I don't remember the exact details, but they were basically incompatible electronics. You might be able to get away with swapping the innards, I decided to just buy a new 4.1 dizzy to reset the maintenance clock and keep it simple.

Ranger
08-13-12, 03:49 PM
Also, the rated 125 hp was more like 50 hp. The engine would struggle in 2nd gear with the pedal through the metal going up Snoqualmie pass and passed by semi's that were carrying a full load. By the time you got to the top of the hill, 25 mph was as fast as she would go.
:histeric: I had forgotten just what a gutless wonder those engines where. I can remember mine (I actually had 2) downshifting with the cruise set and driving into a strong headwind. I think both of mine had permanent creases in the seat cushions from my attempts to pass on a 2 lane highway.

dennis93coupe
08-13-12, 06:01 PM
I worked for a guy years ago that had an Eldorado with a HT4100 in it. Wasn't bad enough it didn't have power enough to pull a sick whore off a pisspot, let alone all the times I had to drain the cheap gas and water in his fuel system. Most of the time I always thought the water in his gas was the problem until I went on a road test with him and he told me that is how it is supposed to run.

Edahall
08-14-12, 12:29 AM
Here's what was partly responsible for the terribly low power. Hint... Take a look at what has come out of the end of the pipe.

http://img.photobucket.com/albums/v48/rhedahl/P1030107.jpg

Plugged up all the injector holes on the 4.9 with some bolts and RTV. Those injector holes don't need to be used since I've converted it over to TBI.

http://img.photobucket.com/albums/v48/rhedahl/P1030110.jpg

The distributors are different between the 2 engines but wanted to avoid swapping them. So I swapped the innards instead. I hope it will work.

http://img.photobucket.com/albums/v48/rhedahl/P1030111.jpg

4.9 engine ready to be installed.

http://img.photobucket.com/albums/v48/rhedahl/P1030109.jpg

Ranger
08-14-12, 10:35 AM
A clogged CAT will certainly kill performance.

Edahall
08-15-12, 04:00 PM
Got it running. I'm currently working out some of the kinks. The exhaust was a major success. It sounds very good and produces just the right level of noise.

ehall
08-15-12, 06:20 PM
good to hear... pretty simple swap once the mystery is taken out of it

Edahall
08-16-12, 01:18 AM
Here's how the 4.9 engine sits in the car. It runs very smoothly and has tons more power than the HT4100. So far, I'm very pleased with the results and I'm glad that I saved this very well built car from being sent to the crushers and recycled into a Smart car. With only 80k miles on the heart transplant, it should last for a very long time. Also, my homemade exhaust fits like a glove and sounds like some of the more expensive exhaust systems out there. It was easy to do with the engine out.

I don't know if anyone else is interested in saving an old car like this but if someone is, I would be willing to write something up on how to do this. The job was not difficult but there was someone planning and homework that went into this to make the conversion successful.

http://img.photobucket.com/albums/v48/rhedahl/P1030116.jpg

ehall
08-16-12, 04:24 AM
What did you do about the accessories and brackets?

Edahall
08-16-12, 10:34 AM
I ended up using the bracket (that supports the alternator and power steering pump) from the old 4.1 engine. It fit pretty well except 1 bracket feet bolt hole in the back (of the bracket) did not line up and I had to put some washers under the front two bracket feet bolt holes. I didn't have the accessories from the 4.9 so for me, this was the preferred route to take. The bracket is plenty stout enough even with the 1 feet bolt hole not bolted down.

I also used the 4.9 distributor with some of the guts transferred from the 4.1 distributor. This was a lot easier than swapping distributors. I never even had to set the timing.

dennis93coupe
08-16-12, 06:13 PM
Did you happen to get a picture of the block on the side down behind the starter? In 92 they were supposed to have changed the casting with ribs on the side and a thicker oil pan rail. Glad to see you got it running.

brougham
08-18-12, 08:28 PM
That's neat that you got a 4.9 working in it and without much extra work by the sounds of it. Why did you use 350 fuel injectors? 305 would have been sized better for that engine.

Edahall
08-18-12, 08:45 PM
That's neat that you got a 4.9 working in it and without much extra work by the sounds of it. Why did you use 350 fuel injectors? 305 would have been sized better for that engine.

I got the engine running on 4.1 injectors but it was hardly derivable from being too lean so I installed a set of 350 fuel injectors that I had laying around. Eventually, I'm going to install a 4.5 throttle body with 4.5 injectors. The 4.5 throttle body is a lot larger CFM than the 4.1 so it should match the 4.9 engine a lot better.

drewsdeville
08-19-12, 10:41 AM
Be careful with your injector selection. The pcm's integrator algorithm has it's limits, and the 4.5 injectors will flow about 15% less than the 4.9 would ideally take.

You'll want to choose the injector that gets you closest to the ideal fuel integrator value of 128. You should be able to view this through your on-board diagnostics.

Edahall
08-19-12, 04:05 PM
Be careful with your injector selection. The pcm's integrator algorithm has it's limits, and the 4.5 injectors will flow about 15% less than the 4.9 would ideally take.

You'll want to choose the injector that gets you closest to the ideal fuel integrator value of 128. You should be able to view this through your on-board diagnostics.

With 350 injectors, I'm getting a fuel integrator value of around 123 while accelerating. At idle, it'll go down to 99 at times. While coasting, it's usually 128.

I tried running mixing a 350 injector with a 4.1 injector and it ran poorly and the fuel integrator value was generally around 135.

Is 305 TBI injectors the best choice or is there something that's even a better choice?

drewsdeville
08-20-12, 05:30 PM
With 350 injectors, I'm getting a fuel integrator value of around 123 while accelerating. At idle, it'll go down to 99 at times. While coasting, it's usually 128.

I tried running mixing a 350 injector with a 4.1 injector and it ran poorly and the fuel integrator value was generally around 135.

Is 305 TBI injectors the best choice or is there something that's even a better choice?

I would assume that the 305 injectors would be a decent match, but I can't offer any experience-derived advice. Ehall has done this swap, as he mentioned. Maybe he can post what kind of integrator values he gets.

ehall
08-23-12, 02:27 PM
My 85 ECM doesnt seem to publish an integrator value. The nearest display option is injector pulse width (0.6), which runs from about 2.5 at cold idle to 1.7 at warm idle.

Also just noticed that the car did not go into open loop after about 10 minutes of driving. Coolant temperature got warm enough, so maybe the O2 readings are confusing the computer (the sensor does not have an integrated heater or temperature switch). Could also be the replacement ECM having trouble. That would certainly explain why fuel economy is so poor. I'll have to check into it, but I need another battery first, and want to install an adj. FPR in the TBI, and need a few other things, but I'm working on other stuff that is more important right now. /hijack

Edahall
08-24-12, 01:07 AM
Try this to get your Fuel Integrator value.

1. Press (Off & Warmer) simultaneously to enter diagnostics.
2. Wait until code .7.0 is displayed.
3. Press (Lo) repeatedly until P.1.4 is displayed
4. It'll show a Fuel Integrator value ranging from 0 to 255.

ehall
08-24-12, 09:18 AM
My 85 doesn't have 1.4. It stops at 1.3 (PROM ID). I can give you injector width (above) and there is an O2 reading that might be useful for something.

brougham
08-28-12, 12:11 AM
With 350 injectors, I'm getting a fuel integrator value of around 123 while accelerating. At idle, it'll go down to 99 at times. While coasting, it's usually 128.

I tried running mixing a 350 injector with a 4.1 injector and it ran poorly and the fuel integrator value was generally around 135.

Is 305 TBI injectors the best choice or is there something that's even a better choice?

I think the 4.5 throttle body would be the best match unless the 305 is similar in size sine it is closer to 4.9. Cadillac engines are oddballs but I think the 4.9L uses the smaller injector size that is probably the same as a 305. 350 uses bigger injectors.

ehall
08-31-12, 07:26 PM
What's the current status? Any more changes?

Edahall
09-04-12, 11:02 PM
What's the current status? Any more changes?

Yes, I ended up installing a 350 throttle body.

steelybill
12-10-12, 11:33 AM
Great thread. Not sure I want or need to go that route myself. My 4.1 actually runs great, after a bunch of fooling around with it. Getting rid of the converter surely helped. It has to come out ( again) to replace the rear main seal. I put new main bearings in it last year, and should never have replaced the rear mains, because I disturbed the rear seal when I removed that rear bearing cap. At least I got rid of the typical "thump" at idle.
Had oil pump problems, because of the pickup tube breaking off twice, on new pumps.
Biggest problem with this car is the brakes, which really suck. Vacuum pump is a sick joke.
Good to hear that the 4.9 is working out though.....

gsim
12-10-12, 11:39 AM
That is a pretty ambitious project. I do believe tho that if a car is otherwise good, it is worth replacing an engine on one. I am not sure if I would try it on mine though. However it could be easier than what you are facing being as mine is an 84 Deville with the 4.1 engine. BTW, I have only 126,000 on my car, so I suspect it may outlast me. Other than being underpowered as all of the 4.1 engine cars were, I have had no complaints whatsoever. Mine has been extremely reliable, although not popular. In our part of town, it is easily the oldest car in any parking lot nearly any day of the year. I still have the original freon in the air cond. system.

I did have to replace a water pump and it really sucked. Worst water pump replacement I ever did, bar none! Thought because of all of that room in front of the engine after shroud removed would be a piece of cake. Nope! Had to do my '95 BMw which I thought would be bad due to lack of any extra space and it turned out to be the easiest I ever did. Who knew?

I am surprised that wire harness, etc would work on such a conversion. I thought of removing the tranny to replace the rear main seal on the engine, a real leaker. But the thing looks like more trouble than it is worth. I park it over a drip pan and that takes care of that! Torx bolts to pull from bellhousing. Never saw those before and looks to be a bit tight to work on, for a rear wheel drive car. Maybe I am wrong and it is not a bad job???? Anyone know???

Good luck on your conversion.

Gerry

The Gold
12-10-12, 01:46 PM
Great thread. Very interesting.

Your car must be a woot to drive now.
I just understood the throttle body injector (TBI) general concept.

Can you post a picture of it sometime?

Also I am curious whether that system is controlled by the onboard computer and whether you used the original computer or replaced it with a 4.9 L engine computer/eprom ?

Edahall
12-12-12, 11:52 PM
Great thread. Very interesting.

Your car must be a woot to drive now.
I just understood the throttle body injector (TBI) general concept.

Can you post a picture of it sometime?

Also I am curious whether that system is controlled by the onboard computer and whether you used the original computer or replaced it with a 4.9 L engine computer/eprom ?

Yes the system is still controlled by the original 4.1L computer. There was no change whatsoever there. From the pictures, nobody can tell that the engine is not original other than the fact that the valve covers say PFI. But when you get into the car to drive it, it doesn't feel like a 4.1L.

cady lover
07-14-13, 11:26 AM
hi I hope someone can answer some the questions I have. I have a 88 Fleetwood fwd, a few years ago I put on a 4.9 in it. the smog pump is on the engine because I thought I need it. can you anyone please tell me what do I do with all the parts that connect to the smog pump if I remove the pump. the cables, the hoses.

dennis93coupe
07-14-13, 01:50 PM
What cables are you asking about?

drewsdeville
07-16-13, 05:17 PM
Remove the hoses from the cat, manifold, and air duct and cap the holes. Remove the diverter valve. Remove the pump and install the substitute brace (from a 4.9) that bolts from the AC compressor to the bracket behind the timing cover. Install 4.9 length belt.