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1984 Cadillac Fleetwood Brougham
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Discussion Starter #1
I'm new to this site and have had several '79-'89 Fleetwood/Brougham Cadillacs. All the cars I've owned have had anything from the 425 BB to the standard carbed 307.

I just picked up a fairly clean '84 F/B with the 4.1 engine and have a few questions on it as I am completely unfamiliar with these.

Are these durable engines like the 307's?

Do they have an overheating problem like I've read elsewhere?

What are the pros/cons of this engine VS the 307?

Thanks for any info
 

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1975 hearse, 1976 hearse
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865 Posts
The HT4100 4.1 V-8 was a first for Cadillac. However it had some issues. Cooling system maintenance was absolutely CRITICAL on these engines. When cadillac said to use a certain additive and type of coolant they MEANT it. typically, most cadillac owners never paid attention to those pesky details and the engines suffered greatly. They were also VERY sensitive to overheating. Get it too hot, and it was cooked.

Some very early examples were known to have the cylinder bores so badly out of line that the engines would suffer spectacular catastrophic failures within 2k miles! Oil condition was also something that was critical.

This was not one of cadillac's best.

It was also radically underpowered. I think it had 125 hp in its initial form. It was later given a 10 hp boost but that's still relatively low for a large car. The engine was deemed not worthy for limousines and commercial chassis use, those cars retained the trusty cast iron 368. I don't believe there are any performance parts for these engines. The 307 Olds motor was no barnstormer either - I had a Caprice with that motor and it was so slow as to require constant flooring of the accelerator just for normal driving. BUT, it was cast iron and reasonably reliable. Many Olds performance parts will work with this engine, so increasing hp from the factory 140 isn't too tough.

If the 4.1 hasn't been abused or worse - neglected, it will work. But its not one of the best examples.
 

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1984 Cadillac Fleetwood Brougham
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4 Posts
Discussion Starter #3
Well thanks for the info. Is a 307 swap fairly easy to do on these? I know it fits, but I mean from the standpoint of hooking everything up, wiring, emissions, transmission, transmission linkage etc. I may have a running carbed 307 I can get to swap in if everything will hook up correctly.
 

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2014 ELR
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10,384 Posts
They are pretty fragile, and very underpowered. However, if you take care of it, and drive it like Miss Daisy, you can get them to survive.

Pro: fuel injection
Cons: hp, reliability, durability

Don't stress. If it made it this long, it will probably be fine. Or, it may have been replaced already. If it was a dealer swap, there will be a tag on the passenger side of the engine block behind the engine mount.

I hope none of the 4.1 owners think I am disparaging their engine. Far from it. I take care of my mother's 84 FWB with a 4.1. It runs great. It was taken care of very well, and the engine developed a rod knock at 50k miles. The engine was replaced at the dealer, and the reman has gone almost 100k miles since.
 

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1975 hearse, 1976 hearse
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865 Posts
I agree w Jay. Baby it and the 4.1 will live - it made it this far. It may be easier than doing a swap although I don't think a 4.1/5.0 swap would be too tough.
 

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1984 Cadillac Fleetwood Brougham
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4 Posts
Discussion Starter #6
Thanks again, I'll try and take some pictures when I get it cleaned up. It's white with a white top and blue interior. It's missing the rear filler peices but I think I can get them. The engine that's in it runs really well. I just did some reading on it and was suprised to hear of overheating problems, add in the fact that I have never heard of this engine until today and you can see my concern.
 

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Super Moderator
2014 ELR
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10,384 Posts
I would do a coolant flush, refill with proper mix (and the correct tabs). Then, basic maintenance stuff if it hasn't been done. Belts, hoses, cap, rotor, wires, plugs, oil, filter, etc.

Car sounds like a twin to my mom's 84. My 81 is parked next to it.

 

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chevy 350 powered 86 FWB, 00 safari h.t. 66 toro, 83 lesabre
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6,397 Posts
a 307 should be mostly drop in. you might have to change your accessories on the engine. the trans should work. you will have to change the computer and wiring harness.
you asked for pro and cons comparing 307s and 4.1's
heres the 307
pros
car will idle down street at 30 mph
runs silent
highway acceleration (50-70) is good
15-18 mpg
307 can be tuned using factory parts to do a sub 9 second 0-60.
incredibly reliable with super basic maintenance
parts are cheap and readily available
cons
0-60 in 13 seconds (swirl port heads, factory tune)
car is anything but quiet or refined at WOT and once the 4bbl opens, fuel gauge drops significantly
may need premium fuel
motor is EXTREMELY EGR sensitive and will not run properly without EGR system or if EGR system is not functioning (vacuum leak/ carbon buildup/ bad EGR valve). the motor is made to run with the computer and made to run with EGR. malfunctioning EGR system will result in poor mileage, loud spark knock (sounds like diesel motor from tailpipe), and possibly engine cutting out/ vapor lock (worst case scenario)
 

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1989 Brougham d'Elegance, 1985 Fleetwood Brougham *Coupe*
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4,256 Posts
The 4100 is as reliable as any other engine. You just need to take care of it. To make it last you need to preform routine coolant system maintenance (more than usual), which prevents the galvanic action from eating the block and heads away.

There is not much difference between the 4100 and the 307. Because 4100 cars use a different differential (to compensate the lack of power) they accelerate, up to 2nd, faster than a 307. After 2nd gear, you can't really do anything to make the car move. The 307 Broughams are more consistent through the gear ranges. And as Kevin stated, the 307 is more versatile in modifications (the block is the same as the 350 and 403, so there are a lot of components that will swap), where the 4100 is basically you get what you see.
 

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1984 Cadillac Fleetwood Brougham
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Discussion Starter #11
Thanks for the info. If I wanted to go the rout of swapping the car, how would I go about swapping the harness and computer? If I'm putting in a carbed 307, do I really need a computer? Can I not hook the ignition up into the stock harness? I'm not familiar with these swaps at all on GM products but can do it if I know what works and what doesn't. I know ways to get around it on Mopars, just not familiar with the GM stuff.
 

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1991 Cadillac Brougham D'Elegance 5.7 Litre, 1994 DeVille
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6,796 Posts
4.1s are pretty much near the bottom of the list as far as reliability goes. But surprisingly they seemed to have far less problems in RWD cars then the front drivers. If it's running good take good care of it and just drive it.
 

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chevy 350 powered 86 FWB, 00 safari h.t. 66 toro, 83 lesabre
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Thanks for the info. If I wanted to go the rout of swapping the car, how would I go about swapping the harness and computer? If I'm putting in a carbed 307, do I really need a computer? Can I not hook the ignition up into the stock harness? I'm not familiar with these swaps at all on GM products but can do it if I know what works and what doesn't. I know ways to get around it on Mopars, just not familiar with the GM stuff.
heres a good 307 site describing what the computer does (also has good tricks to tune up a 307.)
http://performanceolds307.tripod.com/id1.html

if the computer is disconnected and a manual carb is installed, the motor will not run properly (horrible mileage and poor performance). you would have to reinvent the wheel, so to speak. new or reworked heads, intake, carb, exhaust manifolds, etc. the 307 is a good putt around town motor, but if you're paying to buy a used motor and have it put in, might as well shell out the same amount and get a better motor with more power ans similar gas mileage.
IMO, your best (cheapest/easiest) swap in place of the 4100 is a basic carbed 350 chevy V8 from the 70's. the older 350's have no computer, very little wiring, only a couple basic sensors, and are reliable as all get out. performance parts are cheap and easy to find.
the base 70's 4bbl 350s made roughly 200hp and 300ft/lbs of torque with the crappy 76cc heads and dished 12cc pistons, a lumpy stick for a cam, and incredibly heavy low flowing cast iron intake.
since 350s were put in caddies from 90-92 (FI form), the motor mounts, AC brackets, AC pulley, and all the other parts you'll need for a swap are already available at any auto parts store.
you will need to upgrade to a turbo 350 or turbo 400 or 700r4 trans with the 350 and get the driveshaft from a 90-92 rwd caddy for the 700r4.
I am currently putting a 350 chevy and 700r4 in my caddy to replace the 67xxx mile 307 (long story) all in all including labor and parts, my swap will come in under $1800 and will make 220 to 250hp (new intake, DIY exhaust with no cat and low restriction mufflers, tuned 600 quadrajet carb, rv camshaft on 5y/o rebuilt 350.)
sorry for the drawn out response, but pretty much, installing a 307 is a waste of time and money. I have nothing against it, and I loved mine to death, but if you're doing an engine swap, you might as well go for a higher output motor that costs the same and gets better mileage.
 
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