caddy 4.1 swap... anyone?

H

hummkee90

NAXJA Forum User
Location
Ramona, CA
I have a 86 2-door with a 2.8 thats seen better days. i just happen to have a caddy 4.1 v8 out of a rwd Allante with harness etc. fuel injected goodness and from what i understand it shares the same 60* bolt pattern. has anyone ever tried this? i do have fab skills so the mounts are no problem. anything im not seeing.
 
Is that motor termed the "Shortstar" ala Northstar? I think JP mag did a swap with one. Might check their archives.
 
I have an 86 also that had a 2.8 in it. You will have to change your hood and front radiator supports to the 4.0 stuff. You will have to use a custom radiator I think too and dual efans. Check where the oil filter is. If it is where the front drive shaft will be you will need a remote oil filter and or cooler. Check position of power steering pump. You may need a small size pulley. Advance Adapters used to have them anyway. Plan on venting your hood for air flow.
 
You don't want to use the 4.1 for anything. It has okay torque but it's not very robust and has a whole lot of problems (I have an 85 DeVille with the 4.1). If it was a 4.9 I'd say go ahead, since those are dropped into different cars pretty often, but the 4.1 is a real dog and not worth the trouble.

You should ebay the Allante parts, since they had different intake manifold and some other stuff that produced better HP and TQ at the top end.
 
hummkee90 said:
I have a 86 2-door with a 2.8 thats seen better days. i just happen to have a caddy 4.1 v8 out of a rwd Allante with harness etc. fuel injected goodness and from what i understand it shares the same 60* bolt pattern. has anyone ever tried this? i do have fab skills so the mounts are no problem. anything im not seeing.
Click to expand...

I do'ntk now much about the Caddy HT4100 for power & durability, but I also believe it shares the same "Metric" bell pattern as the V6-60. It's not a "Northstar" (which was somewhere around 280ci,) or a "Shortstar" (which was the Northstar less two cylinders.)

Given that, look for a 1989-up S-series for a transmission donor if you're so inclined, since the Baby 904/30RH wasn't anything to write home about, and it was actually well-suited to the GM V6-173 (which was also best used poured full of cement and used as a sea anchor.) Get the S-Series powertrain, and you can score a THM700R4/4L60 (tougher transmission with overdrive) and an NP231C transfer case (1.25" wide drive chain, vice 1" for the 231J.) (1992-ish and up 4L60 are the 4L60E - grab the control electronics as well.)

I won't say anything as to the durability of the Baby 904 behind the HT4100 - except to say that it probably wouldn't last long, even on a fresh overhaul! The A904/Baby 904 was really meant to go behind 4cyl and midget V6 engines. Putting one behind the Slant Six probably wouldn't have done the thing any good, either.

If you do decide to go forward with the project, I'd love to hear about it! Also, feel free to at least bounce ideas off of me if you like, and I'll help you where I can. I look forward to this build thread (or just send me a copy of your notebook when you're done - this should prove interesting...)
 
Feel free to bounce questions off me too. I have the 4.3 V6 with a 4L60E in mine. It is a lot of work, but there is something wrong with throwing away a perfectly good XJ
 
5-90 said:
The A904/Baby 904 was really meant to go behind 4cyl and midget V6
Click to expand...
minor correction; the A904 was designed to go behind the Chrysler slant six and 273/318 2bbl. The later models/and baby 904 have a bunch of cheaper parts in them to save money and weight. A decent rebuild should be good for 230 hp(gross) - the original rating for the 318.
 
tbburg said:
minor correction; the A904 was designed to go behind the Chrysler slant six and 273/318 2bbl. The later models/and baby 904 have a bunch of cheaper parts in them to save money and weight. A decent rebuild should be good for 230 hp(gross) - the original rating for the 318.
Click to expand...

Thanks. Yeah, I was just perusing my transmission notebook, and saw the difference between the A904 and the Baby 904.

I'm still not sure that I'd want to put a Baby 904, that was originally behind a 2.8L V6, behind any engine that's worth putting fuel into...
 
it has the stock tranny hooked to it from the Allante (though im not sure what that is) so im gonna do a little more research before i dive into this. thanks for the info. i"ll keep you posted
 
The transmission is a 4T60 (aka THM-440-T4), s a hydraulic 4-speed for FWD. I have the same thing in my 85 DeVille, although the one in the Allante was supposedly strengthened (maybe a better TC dunno). Later Cadillacs had the 4T60-E and a TCU to control it but it was basically the same thing. People on the Cadillac boards talk about them poorly but mine has been real good to me.

If you are interested in seeing what's required to bolt one of them up here are some threads for some 4.5 and 4.9 swaps in other vehicles. I strongly recommend against it however, since the 4100 is such a POS

4.9 into a Fiero (common swap) http://www.fieroaddiction.com/caddy49b.html

4.9 into an MG (England) http://forum.britishv8.org/read.php?6,13482

4.5 into Isuzu Trooper (seen this twice) http://myweb.cableone.net/bcanderson/trooper/Cadillac/cadillac.htm

ps--the bellhousing pattern is the GM Metric
 
Last edited:
Don't the 4.1's eat headgaskets like crazy? I would do a northstar!!!!!
 
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