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Thread: Any recommendations on 4.9 swap?

  1. #1
    Senior Member
    Join Date
    Dec 2006

    Any recommendations on 4.9 swap?

    After a recommendation from Dave (thanks funnywheels) I have decided to use a 4.9 caddy PFI engine in my project. Have done alot of research on this but wanted to get any additional ideas from you guys here. Looking for diagrams for the engine mounts, performance modifications info, etc. I am at work in the middle east and have spare time every night to do research, not much to do in the desert at night. :-[ Any and all help much appreciated. email is if you prefer. Thanks guys. 8)

    Building a F40 replica, 4.9 caddy, 5 speed.

  2. #2
    Senior Member
    Join Date
    Dec 2001

    Re: Any recommendations on 4.9 swap?

    Welcome to 4.9 world. Although I don't have any drawings or diagrams, I don't mind telling you how I did mine. I decided up front I didn't want the extra expense and work of installing a standard transmission, and went for an automatic. I figured if I was using an automatic then I probably should use the Cadillic trans and driveline. Then I decided if I was using the complete Caddy drivetrain, why not use the Caddy cradle. Just another way to go that you could consider.
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    And the joke is,<br />when he awoke his,<br />body was covered in Coke fizz !

  3. #3

    Re: Any recommendations on 4.9 swap?

    Check out There's lots of info there that was essential to my swap.

  4. #4
    Senior Member
    Join Date
    Dec 2006

    Re: Any recommendations on 4.9 swap?

    Have been through everything on fieroaddiction. Was that your primary souce for the swap? Should i need the clitons for the caddy? How happy are you with the configuration? Anything you wish you would have done differently? ???

    Building a F40 replica, 4.9 caddy, 5 speed.

  5. #5

    Re: Any recommendations on 4.9 swap?

    Well, to be honest, my swap isn't quite finished, and has been sitting as is since last spring. I got info from this site as well, but I trust FieroAddiction more, though I'm not sure why:
    I still have to decide on an exhaust configuration - the stock Caddy exhaust comes out in the center of the car, right where the fiero trunk compartment is. I'm still milling over a couple different designs. Also, I never finished the air intake. The shape and diameter of the two cars differ, and I haven't heard of any good off the shelf replacement.

    Also, my alternator hits the decklid. I'll have to redo the hinges, and shave some off of it to accommodate this. I heard somewhere that you could use a Nissan alternator that was physically smaller? We put a tensioner for the pulley on the car rather than going fieroAddiction's route -modifying the alternator bracket so that the whole thing pivots. This would have lowered the alternator enough to miss the decklid, and I'd have preferred to go that way.

    We cut out portions of the Cadillac cradle to weld into the Fiero cradle. FieroAddiction shows where he gets his motor mounts from, but we went cheap and reused the OEM Cadillac mounts. It did save a buck, but cost a lot of time and energy cutting, welding, reinforcing what we cut out, test fitting the engine, etc, and I'd recommend going a different route.

    One thing we did that worked well was to separate the original engines from their transmissions. We put the caddy engine on the fiero transmission (they bolt right up). Then we put the caddy engine on the hoist, and bolted the Fiero transmission to the cradle (while connected to the caddy engine). With that setup, we were able to leave the transmission in the stock location while we mocked up the mounts for the engine. having the transmission nailed down took a lot of the guesswork out of where the whole drivetrain was supposed to be on the cradle. Once that was done, we removed the fiero transmission, added the caddilac's transmission and mocked up our new mounts.

    I've been working on the car with my dad, who did almost all of the wiring. This again added a lot of time to the project, and in the end I think I'd have prefered just to pay someone to do it. (I think there are a few places that will do the wiring for $700 -you supply them with the two donor harnesses)
    That said, if you wire it yourself, FieroAddiction gives a pretty thorough explanation of defeating the passkey system, wiring the caddy transmission (which I would recommend if your car is automatic), and adjusting the speed sensor.

    The stamped '4.9 V8 PFI' on the valve cover goes in the front of the car (along with the oil dipstick). I hear that they aren't interchangeable from front to rear, but you can get an extra stamped one and put it on the rear?? Anyway, I plan to do something there eventually, but I'll have to take more time to investigate it.

    I had some trouble with the waterpump seal. It may have been that my donor car was wrecked, though I don't think so. FieroAddiction mentions the caddy water pump somewhere... Anyway, if you can find a way to test the seal while the engine's out of the car, i would do so.

    The Chilton's/Haynes manuals won't help you with the swap much. They are a good investment, but aside from detailing how to drop the cradle out of the car, there's nothing much that is relevant to the swap. The wiring diagrams are nowhere near as detailed as to what you'll need.

    I got my driveshafts from stock GM vehicles. If you do so, take your old driveshafts with you. It took a couple trips to the store for them to get the right ones for me. They did fit when I got the right ones. Anyway, count the splines on each to make sure you get what you ordered. I'm not sure about those parts guys sometimes. Off the top of my head, one shaft was from a manual trans fiero, and the other was from a 1990? Pontiac 6000 with the 3800 V6 and either light or heavy duty brakes, I can't remember...
    From FieroAddiction:
    The stock Fiero axles cannot be used with the four speed automatic. For a 4T60 you can use right and left axle assemblies for a '89 Pontiac 6000 with 4T60 and light duty brakes. The correct part numbers are A1 Cardone P/Ns are 60-1115 and 60-1078 or CCT 8471 left and 8430 right.

    For a 4T60E you can use the same left axle for a '89 Pontiac 6000 with 4T60 and light duty brakes on the left side, and a left axle for a manual Fiero on the right side. Some people have reported having problems with the Fiero axle on the right side, but they have always worked well for me. There are plenty of other combinations of parts that can be used to assemble axles that will fit, but those are the simplest solutions. They can be purchased off the shelf at most auto parts stores for about $60 each and install without modification.

    Ultimately, I'm probably not the best guy to look to for info on the swap, since I haven't quite finished mine. Dale's probably a better guy to ask! There's lots more info on Pennock's too:
    While you're there, you may want to investigate the 3800 supercharged V6 swap - lots of people have a preference to one or the other, and there's lots of pro's and cons for each.
    Ultimately, the car is going to be a lot of fun - it really wants to get up and move. I really should get in gear and finish these last few things!
    Best wishes!

  6. #6

    Re: Any recommendations on 4.9 swap?

    One more thing - FieroAddiction shows where you notch a part off the bellhousing since the Fiero starter hits the Cadillac. If you need to do so, I remember someone on Pennock's using a physically smaller starter, again may have been from a Nissan? Anyway, search Pennock's as there is a replacement starter that will work without cutting a notch out of your transmission...

  7. #7
    Senior Member
    Join Date
    Mar 2005

    Re: Any recommendations on 4.9 swap?

    I would check out The Fiero Factory in Alabama, they have a web-site that has been recently updated. If you don't want to do the conversion yourself they do an awesome job. They did two of my replicas for me. I think it is a great powertrain especially if you want a reliable daily driver with great low end torque.
    Take care. Bill

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