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Discussion Starter · #1 ·
Hello,
I have a 1985 Seville and a 1984 Toronado complete swap happening and am curious to hear from the pros if the tail end of this project is getting into crazyville.
So to be consise, I have a sweet, low mileage (40k) 85 Seville with a mildly leaky 4100.
After reading these forums I was inspired to take that out and proceed with upgrading my Seville with a pre76 Olds Rocket 350. This project is going well, down to the wiring now and probably will be consulting here later for help with stumpers.
But for now my question is about using the 4100 that I removed from the Cadillac in the Toronado after this Cadillac project is done.
The Toronado is also low mileage and I don't really want to just give up on it. In fact, the 4100 needed a place to go when I took it out, and the Toronado was just sitting there with the hood up, it seemed like a good idea to just set it down in there.
This whole idea was reinforced buy all the other parts that I took off of the Cadillac, it is nearly everything that I need to complete the install into the Toronado! The gas tank w/ pump, complete exhaust, motor mount brackets, everything. Too good to give up on! Except for when it comes to the computer (ECM) that controls the 4100.
So the Question is, how much of the array of inputs and outputs need to be hooked up to make this motor run in this Toronado? Is this altogether stupid? A deal breaker?
I am planning on leaving the 4100 ECM in the Cadillac and connecting as much as possible to it with the 350.
Guessing I'll need to get a used ECM for the Toronado for timing advance control, and fuel injection control, but it gets pretty deep in it's sensing of what's happening with the Cadillac. How much interfacing will it need?
I guess, "what are the bare essentials?" Is a better question.
Is it possible to take some of the "HT" away from the 4100 and still have it run?
I usually stick with older simpler stuff.
 

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1984 Eldorado Biarritz, 1983 Sedan deVille
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Keep the entire throttle body injection system and put it on the Olds engine. It is the best part of the 4100 system.

Transfer the distributor from the 4100 to the Olds engine. I do not believe the Olds engine had a provision for a MAT sensor, if it did not, find someone to weld a bung onto the manifold and drill & tap a hole thru it that the 4100 MAT sensor can sit in. Run the 4100 coolant temp sensor to wherever the coolant temp sensor is on the Olds. Buy 350 chevy TBI injectors and swap them into the 4100 throttle body, and get a quadrajet to TBI addapter (watch hood clearance here) to put the TBI on the Olds. It would be in your interests to not reinvent the wheel as the fuel injection system will work with the coolant, MAT and MAP sensors hooked up.

I think you are nuts to put a 4100 into the Toronado. But if you do, I would graft all of the CCC system onto it. Everything will work. But, why?

Have you swapped the suspensions yet?
 

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Discussion Starter · #3 ·
Keep the entire throttle body injection system and put it on the Olds engine. It is the best part of the 4100 system.

Transfer the distributor from the 4100 to the Olds engine. I do not believe the Olds engine had a provision for a MAT sensor, if it did not, find someone to weld a bung onto the manifold and drill & tap a hole thru it that the 4100 MAT sensor can sit in. Run the 4100 coolant temp sensor to wherever the coolant temp sensor is on the Olds. Buy 350 chevy TBI injectors and swap them into the 4100 throttle body, and get a quadrajet to TBI addapter (watch hood clearance here) to put the TBI on the Olds. It would be in your interests to not reinvent the wheel as the fuel injection system will work with the coolant, MAT and MAP sensors hooked up.

I think you are nuts to put a 4100 into the Toronado. But if you do, I would graft all of the CCC system onto it. Everything will work. But, why?

Have you swapped the suspensions yet?
Thanks so much for your reply! I was hoping you'd see this.
Really good and smart ideas for the 350 in the Cadillac, it is a unique car and is gonna be so amazing with this upgrade.
But, I have a Holly Sniper Quadrajet rig for the Olds 350, and a Progession Ignition distributor for timing control already.
About the Toronado, the why is just because it is all there, a low mileage motor and car that work together mechanically.
Also, the Cadillac doesn't belong to me, I am doing this project for my friend/boss. He gave me the 4100 and the car. I'm not in love with the Toronado but still seems too good to give up on. It's pretty cool.
So by "graft the whole CCC system into it"
CCC = computer?
If one were to proceed with this crazy idea, I was picturing maybe mounting the computer in the engine compartment and making a cable loom with connections directly to the computer plug tabs.
I do see why No one in their right mind would want to do this, it will be a downgrade for sure from the perfectly good 307 that I can't put back in it anymore, but at least it can be complete again, with a Cadillac motor in it. That sounds like an upgrade to the uneducated ear.
I was amazed at the ease of install in the Toronado, complete with all accessories, it just glided right in.
Do you say it's crazy because of how slow the car will be in the end? Or because adapting the computer to a non computer car is a huge undertaking?
The mechanical stuff is already done. While under the car, I got this bright idea to ask you if this is even doable?
These things have to be hooked to the ECM for sure...
Injector connections, fuel pump relay via oil pressure sending unit, O2 sensor, several more i'm sure.
But what about outside air temp, vehicle speed sensor...
Is it kinda "all or nothing?" situation, that might make it a deal breaker, but if I could just hook up a few engine monitoring, timing control and FI, I might try to continue.
Thanks for considering this ridiculous swap.
As for suspension, no, I added gas charged KYB in the rear that claim to delete the loadleveler system. I am hoping that actually works. As for the front, I have done nothing but installed a heavier motor, and the front is a little higher that with the 4100. So far. Haven't driven it yet though.
The T bars don't appear to be any different.
Also, they are adjustable, right? I do not have much experience with them.
 

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1984 Eldorado Biarritz, 1983 Sedan deVille
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It sounds like you're well on your way, you're doing everything right in having the complete Olds-equipped donor car available to you.

Why is the 4100 in the Olds crazy? Well, it might make you the first person on earth to ever put an HT4100 in a car that didn't come with one. Low power, coupled with all the issues they had, and now 35+ years old and tired...crazy. Personally I have no lost love for the Toronado so seeing it get hauled off wouldn't bother me. That said, I understand your reasoning in that you have all the parts and a nice body to put it into. Talk on my end is cheap, if you have the Toronado there and like it, by all means do what you think is right. This is basically the issue with doing a swap like this nowadays, everything is so old now that it is either a well-preserved car with everything you need in good condition to do the swap that you feel bad mutilating, or a complete junker that will have parts damaged or missing and won't be much help to you.

CCC=computer command control, GM's gimmicky name for the computer controlled quadrajet at the time. All together, it makes for a very efficient, easy to start and clean/decent performance. You would be wise to keep all of these things and not try to put the Caddy fuel injection in the chassis it didn't come with. I'm sure they make 4bbl to TBI adapters, secure one of them (again, watch hood clearance as there is very little in an E body) and put it on the 4100. Or if possible drill the manifold to fit a 4bbl. 4100 is a wet manifold as is so you will have no trouble with the way that it runs, in fact you may find more power with a working 4bbl than the TBI had.

Sniper may be a different story as I'm sure its a lot more simple, but I don't know what inputs those need.

The torsion bars all look the same but have different spring rates. The 4100 ones are the softest riding as it was the lightest engine. The Olds ones are a good bit stiffer to deal with the extra weight. The bars are adjustable for standing height, but ideally you want to just swap them to keep the ride/handling from getting squirrely.

Opinion on the fuel injection: keep the complete TBI in the Seville, and put the Sniper on the Toronado (if you don't want to deal with the carburetor)

Rear suspension, my experience is that you should keep the level control. KYB shocks change the ride to be too harsh for me for a very minute handling benefit. Without the level control working right, these cars develop a strange "bump steer" that will have you moving around a lot in your lane as you hit potholes. The level control system is very simple, just a compressor/exhaust valve combo, and a single height sensor at the drivers rear wheel.

Best of luck, very interested to see how it works out.
 

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Discussion Starter · #5 ·
It sounds like you're well on your way, you're doing everything right in having the complete Olds-equipped donor car available to you.

Why is the 4100 in the Olds crazy? Well, it might make you the first person on earth to ever put an HT4100 in a car that didn't come with one. Low power, coupled with all the issues they had, and now 35+ years old and tired...crazy. Personally I have no lost love for the Toronado so seeing it get hauled off wouldn't bother me. That said, I understand your reasoning in that you have all the parts and a nice body to put it into. Talk on my end is cheap, if you have the Toronado there and like it, by all means do what you think is right. This is basically the issue with doing a swap like this nowadays, everything is so old now that it is either a well-preserved car with everything you need in good condition to do the swap that you feel bad mutilating, or a complete junker that will have parts damaged or missing and won't be much help to you.

CCC=computer command control, GM's gimmicky name for the computer controlled quadrajet at the time. All together, it makes for a very efficient, easy to start and clean/decent performance. You would be wise to keep all of these things and not try to put the Caddy fuel injection in the chassis it didn't come with. I'm sure they make 4bbl to TBI adapters, secure one of them (again, watch hood clearance as there is very little in an E body) and put it on the 4100. Or if possible drill the manifold to fit a 4bbl. 4100 is a wet manifold as is so you will have no trouble with the way that it runs, in fact you may find more power with a working 4bbl than the TBI had.

Sniper may be a different story as I'm sure its a lot more simple, but I don't know what inputs those need.

The torsion bars all look the same but have different spring rates. The 4100 ones are the softest riding as it was the lightest engine. The Olds ones are a good bit stiffer to deal with the extra weight. The bars are adjustable for standing height, but ideally you want to just swap them to keep the ride/handling from getting squirrely.

Opinion on the fuel injection: keep the complete TBI in the Seville, and put the Sniper on the Toronado (if you don't want to deal with the carburetor)

Rear suspension, my experience is that you should keep the level control. KYB shocks change the ride to be too harsh for me for a very minute handling benefit. Without the level control working right, these cars develop a strange "bump steer" that will have you moving around a lot in your lane as you hit potholes. The level control system is very simple, just a compressor/exhaust valve combo, and a single height sensor at the drivers rear wheel.

Best of luck, very interested to see how it works out.
Thanks again for your input/expertise! I REALLY appreciate it.
I love the idea of putting a carburetor on the 4100 and not dealing with the ECM/FI at all.
This may sound silly but, I want the Toronado end of this to be as simple as possible.
I have a question for you about the timing control. Both cars have ECM spark advance control, not oldschool.
do you think the distributors for the 307 w/CCC and the 4100 system are the same?
 

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Right on with the Toronado end of it. I would just put all the parts off the 307 onto the 4100 (and of course re jet the carb) Only point of contention is 4bbl to tbi adapter and overall height; very little clearance.

I believe the distributors will swap between the two. They are different in terms of internals and connections, but IIRC all GM small blocks shared a common distributor size. This is what makes retaining the TBI on the olds-swapped Seville possible, even though I know you’re not going that way.
 

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When you're finished with the Oldsmobile swap into the Cadillac, would you mind taking a few pictures of the completed engine bay? I'd love to see the finished product.
 

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Discussion Starter · #8 ·
Why are there 2 temp sending units on both the 307 from my 84 Toronado, and on the Seville HT 4100?
4100 actually has a third metal temp sensor.
It one for the gauge, and the other for the computer?
Thanks
 

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One temp sensor is coolant temp at the front of the engine. The other is for intake air temp. Both of those feed the computer. The metal temp sensor is something Cadillac always had on their engines. Inside the car there are 2 temp lights, coolant temp and engine temp. Metal temp sensor controls the latter, which should also light with the key in the ignition and the door open as a reminder to take the key. Lastly there is a sensor for temp to prevent the climate control from blowing before the engine is hot enough to provide heat.
 

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I read this quickly but it seems you have a 350 for the Seville, there's a 307 in the Toronado and you are thinking of instead using the HT4100 in the Toronado?! As Smok mentioned the HT4100's are trouble. If you were to objectively list the worst engines GM ever made in terms of durability and re-buildability combined it seems many would argue the HT4100 checks all the boxes as the worst ever.

I love the Toronados. I've had two 1979's and an 1984. I still have one 1979 and a 1979 Eldorado. I would personally hate to see a Toronado scarified for a "bustle back" but to your credit you are planning to save both. Why not find another Olds 350 or an Olds 403? The 307 is much better than the HT4100. I've even heard of others on another Cadillac forum suggesting replacing the HT4100 with an Olds 260 (a boat anchor itself). Anything you do with the HT4100 will cost you more than finding another Olds engine or using the 307. What is/was wrong with the 307? If you are so certain that Cadillac engine is worth saving then you should probably put it on a stand and save it if you ever sell the Seville because someone will certainly want their original Cadillac engine (probably not).

As I read above I saw the suggestion of a distributor swap from HT4100 to Olds. That seemed to be an incredible stretch for several reasons but the most obvious being the mount point to the cam location would need to be common. Take a look at the capture below.

Because you are thinking of a lot of interchange type things one word of caution: The 307 Aluminum intake ports are baby sized compared to the cast iron 350 intake manifold ports. As well there isn't enough meat to enlarge the 307 to the same size.

The KYB monotube gas shocks on the front of these cars work very well IMO. They get the heavy front end under control faster without being harsh.

Scott
 

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