I just wanted to preface with thanking this forum for basically providing me with a wealth of Cadillac HT engine information that nobody else on the internet could provide. The most popular Cadillac forum on the internet couldn't even really provide any solid information for anything. The Fiero guys truly are the mad scientists of the automotive hobby, and I can't thank them enough.

So here's what I have and here's the rough plan I have.

I own a 1988 Cadillac Eldorado with the original TBI 4.5 V8 and 4T60 transmission. Both unopened to by knowledge. I've mostly stuck to custom suspension and exhaust upgrades with this.

I was heavily considering a full LS4 swap, but as you can imagine, "bottom dollar" quickly gets thrown out of the window when you add up the transmission building costs, fuel system, cooling system, exhaust system, and ECU. I have bills to pay, and student loans sucking the life out of me.

A 4.9 swap is about as close to drop-in as I can get with almost zero modifications.

However, I want to do a 4.9 swap WITH the Allante Intake (Why make life easy?), and I could use this forums help for a rough guestimate of what "gotchas" I might need to address. I have read the fuel system runs at a higher pressure for the MPFI Allante variant, so I'm assuming the bare minimum I would need to perhaps swap an Allante fuel pump into my Eldorado's tank.

Mounts would all be the same, and theoretically, even the exhaust should just bolt in without an issue.

Now I do see a thread about swapping the intake, but it seems like you all were talking about tuning it, but I don't see much on the ECU used or any intake mounting concerns.

https://www.fiero.nl/forum/Forum2/HTML/146204.html

That's kind of where my questions start. If I want a 4.9 with the Allante style MFI intake, I need to block off the EGR and I see at least have it tuned to run with the EGR off and increased air flow. Do you guys just use a modified 4.9 ECU or an Allante 4.1 ECU?
I've really only messed with my carbed smallblock on my C10, so I'm honestly not even sure how to push any sort of "tunes" to a pre OBD system anyway. Er, I'm assuming my these would be pre OBD1. Do I need to burn a PROM chip for it?

Additionally, since I'll have the engine out and have to take things apart anyway, are there any recommended cams for the 4.9 I can order? Additionally are there any preventative maintenance things I should do? I'm assuming a water pump, head gaskets, or at the very least valve cover gaskets?

I'm shooting for like a 2k job if I do everything myself. Obviously an optimistic estimate at best.

I'm hoping that this topic can be a good reference point for anyone else in the future attempting a 4.9 swap into a Cadillac of the same era. If the Caddy forums can't help, at least this one can.

The Eldorado:

When I first saw this thread, and then the picture, I thought that you were apparently going to pull a Cadillac 4.9 out of the car in the picture... and just use it for parts, and I was horrified. Then I read that you're upgrading a 4.5 to a 4.9, and was relieved. I don't know anything about the 4.9, but there are a lot of people here who do, so I hope you get all the information you need. That car looks amazing... and I can't wait to see what it's like when it's got a 4.9 in it.

[This message has been edited by 82-T/A [At Work] (edited 08-01-2024).]

Wrong Section of the Forum

Obviously, this is a Non-Fiero Post

Technical Discussion & Questions is the place to ask and discuss all Fiero related technical topics.

The correct section for Cadillac Eldorado Discussion & Questions is:

quote Other Cars There are a lot of knowledgeable gearheads on PFF. So if you have questions about cars other than the Fiero, this is where to ask them.

EDIT
I sent a PM to Cliff about the thread......

[This message has been edited by Vintage-Nut (edited 08-01-2024).]

This forum is made for Fiero owners that collect, maintain and upgrade their cars. While some here have done 4.9L Cadillac swaps in their Pontiac Fieros there is nothing here to help Cadillac car owners. I would suggest you go to a Cadillac forum for info.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: This forum is made for Fiero owners that collect, maintain and upgrade their cars. While some here have done 4.9L Cadillac swaps in their Pontiac Fieros there is nothing here to help Cadillac car owners. I would suggest you go to a Cadillac forum for info.

Miss the part where I wrote they aren't much help and the Fiero community actually does more with the Cadillac HT engine family than actual Cadillac owners?

I'll wait for someone who actually has a Caddy swapped Fiero to get some advice on changing over the engine. If I didn't say anything about swapping this into my Eldorado, you wouldn't know the difference anyway. Thanks for the valued input.

This forum has been the BEST source for Caddy HT V8 build knowledge on the internet, and it is thanks to the creative and hardworking folks in the Fiero community.

[This message has been edited by brandon8696 (edited 08-01-2024).]

quote Originally posted by Dennis LaGrua: This forum is made for Fiero owners that collect, maintain and upgrade their cars. While some here have done 4.9L Cadillac swaps in their Pontiac Fieros there is nothing here to help Cadillac car owners. I would suggest you go to a Cadillac forum for info.

While I agree this should be in the non-fiero section of the forum, Dennis. Turning this guy away, when a good amount of fellas here may have an answer to this question seems kinda backwards. Saying there is nothing here to help a Cadillac owner is both silly and an outright lie. I know plenty of W-Body owners who come here for 3.4DOHC info. Lets get him to the right spot on the forum and see what comes up.

quote Originally posted by Dukesterpro: While I agree this should be in the non-fiero section of the forum, Dennis. Turning this guy away, when a good amount of fellas here may have an answer to this question seems kinda backwards. Saying there is nothing here to help a Cadillac owner is both silly and an outright lie. I know plenty of W-Body owners who come here for 3.4DOHC info. Lets get him to the right spot on the forum and see what comes up.

Thank goodness someone with some nuance. Yes, if Cliff can get this over to the other section of the forum, that would be extremely helpful. I'd do it myself, but I don't see any interface options to do so.
Everything I've learned about Caddy HT modifying, manual swapping, tuning, and even turbo/supercharging has come from this forum over the years. Fiero guys are some of the most creative car builders I've ever met, and I can link dozens of Cadillac topics if they truly think there is "nothing" here haha.

quote Originally posted by brandon8696: Thank goodness someone with some nuance. Yes, if Cliff can get this over to the other section of the forum, that would be extremely helpful. I'd do it myself, but I don't see any interface options to do so. Everything I've learned about Caddy HT modifying, manual swapping, tuning, and even turbo/supercharging has come from this forum over the years. Fiero guys are some of the most creative car builders I've ever met, and I can link dozens of Cadillac topics if they truly think there is "nothing" here haha.

My buddy is basically the foremost expert on 4.9 Caddys... he's done all kinds of Allante 4.9 swaps, primarily into citations. He even built one that works off hydrogen. If you absolutely don't get the answers your looking for here, I'll share his contact information with you. But I don't want to bug him if the questions can be answered here... but I know there's tons of 4.9 people here, so I hope you get some help!