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'94 estate wagon gen IV small block conversion

Old 03-28-2016, 12:29 AM
Junior Member
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Join Date: Mar 2016
Location: Dallas Texas
Posts: 1
Default '94 estate wagon gen IV small block conversion

I'm new to the forum and would like some help figuring out what kind of conversion would get me the best low rev torque and fuel economy. I just have 1,250 invested in this land yatcht and don't care at all about my 1/4 time. The current engine is the 5.7 Lt1 and is a monster but is to much engine for my needs.
I know my way around an engkne bay but have only ever worked on my dads 454 in a 78 suburban and my current car when it comes to v8 power. Im not sure if i would like to stick to a ls1 swap with a conservative cam and minor tuning and mods. Or a 4.3 v6 so i can just rebuild my trans. The 4.2 I6 vortec will give me the same option from my understanding and access to 90% torque at 1600 rpm's
Also if I go v6 I've heard good things about the current camero DOHC v6. Budget isn't much of an issue since this is my first time and i will be taking it slow. As I've said I'm new to this and would appreciate any corrections or feed back
Old 12-01-2017, 07:26 AM
Join Date: Nov 2017
Posts: 44

For what it costs you in money, time, and effort, the payback will take many years. You should leave it the way it is and drive it. The wagons get phenomenal mileage when properly maintained, and the engine is almost bullet proof. They are known to last up to 500K.
The only exorbitantly costly, and difficult item to replace is the optical distributor. It is an expensive item, and costs a lot to have someone swap it. If you can do it yourself, and you said that you are comfortable working in the engine bay, it is reasonable.
The one thing you should check is the post at the back of the electrical box. Some of the early LT1 cars had a zinc post, and they will corrode causing engine compartment fires. You can replace it with a copper one, and that will fix the problem.
Old 12-03-2017, 05:03 AM
Senior Member
Join Date: Oct 2016
Location: Minot, ME
Posts: 369

Do agree with Fred completely. Imagine that would take a decade to see any savings from initial expense if at all. Gas price wise these days is somewhat affordable. Remember back in '64 a few places where it was .25 a gallon still but minimum wage too was only $1.25ph (yup, was there once upon). So a gallon of gas was 1/5 of the hourly rate. Today at $25PH fuel is a bargain IMHO, gas would need to be $5 per gallon to be an equal ratio with the good ole days (speaking for myself here).

Driving habits would be the largest factor to determine for gas mileage. A smaller engine would use more gas as it would have to work harder and to get it all to actually run right? I'd look at a transmission change or rear axle gear ratios, overdrive would be more realistic.

Better yet, purchase a chip or tune that would reprogram the computer for economy. Even back in the 90's engine management had computers, programmable shift points. However would just an engine swap or mod deal with that? Something like this, I'd look at Carid also, a sponsor on this site.

5.7 L motor isn't big at all, my Boss has a 5L and that's only a 302CI (a bit less actually) and on street program in 6th gear will get 27MPG on a trip. Trackey forget it, maybe 16MPG. Let's see, 5.7L would be about 348CI or probably rounded off, rated as a 350CID?

Last edited by Rich B.; 03-19-2018 at 04:16 AM. Reason: Always errors, always......
Old 03-18-2018, 10:52 AM
Join Date: Mar 2018
Location: St. Paul,MN
Posts: 45

I got to agree with the guys here. I’m a life long hotrodder and to jump in and try to modify these cars would be a major, major undertaking even for an experienced mechanic.

Ive already spent about 6 months investigating these cars before I got my current one. GM engineering spent untold man hours desiginging this whole package. There is a security system while primitive by today’s standards will be the first obstical. Try and get an ignition key and replacement FOB. you will be shocked literally at the cost of such a simple item.

There are replacement computer systems so you could isolate the motor and transmission from the rear of the car. This isn’t cheap and is not just break a couple wires. Then mechanically removing the motor and trans and replacing with something else would be a night mare at best. Just refitting the exhaust system if you don’t have pro level welding experience will be a major undertaking too. LS series motors usually require rear sump oil pan conversions...$400 and up. A stand alone wire harness can run $500 and up. The fuel system upgrade can go for anothe $500.

Frankly these cars are one of the best all around cruise cars you can get. They are big but fully equal to today’s traffic.

I’d say fix what needs to be fixed and drive it. There are lots of easier ways to get specialty cars.


Last edited by Bentwings; 03-18-2018 at 10:55 AM.
Old 03-18-2018, 12:23 PM
Join Date: Nov 2017
Posts: 44

The security system is easy to bypass either by putting a properly selected resistor across the leads, or it can be programmed out of the computer.

If replacing the engine, move the donor computer with it, and the only things you need to reconnect are the connectors to the computer (if they are not the same), trans, "key on" wiring, and gauges.

I put a 454 in mine, and other than some issues not related to the installation, it was relatively easy. The engine mounted on the stock engine mounts, and the trans was the same type as the original, but built to handle the higher output of the 454. It would have been even easier with a careful selection of parts. Putting a stock Gen IV 454 with its computer in 91-93 B body wagon is child's play. A TBI 454, its engine wiring harness, and its computer would bolt in, and run without any serious modification in a 91-93 B body. There might be a couple of wiring adaptations, a slightly stronger fuel pump, and a few vacuum line changes, as well as adding electric fans, but that is about it. The hardest part is adapting the stock short distributor from the LO3/5 to the BB, because the stock BB distributor will not fit under the cowl. I would also recommend a trans rebuild for the increased torque, especially the shell, and 3/4 gear parts. You can buy a crossmember for duals, and a shop can make the rest for about 250-500. You can even buy the exhaust parts and install them yourself (the available over the axle pipes for the sedan) need to be modified but all of the other parts can be made by you or your local muffler shop.

No matter what you modify, there is always the return on investment that you must look at.

There are some mods you can make that do not cost much, and are nice. I put flash to pass, LED headlights, different seats, and dual exhausts with headers (for LO5 engine) on for little money and time. Changing an engine is another animal.

Last edited by Fred Kiehl; 03-18-2018 at 12:25 PM.
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