Aces EFI - the best 4.9L Option? (Page 2/5)
psquare75 JUN 29, 08:00 PM
Hey there. I have an 84 skylark and this post convinced me to do the 4.9.

What did you use for mounts? I have a 4 speed so I think my only worry will be shifter cables... maybe.

81 4.9L X-11 JUL 04, 09:21 AM

quote
Originally posted by psquare75:

Hey there. I have an 84 skylark and this post convinced me to do the 4.9.

What did you use for mounts? I have a 4 speed so I think my only worry will be shifter cables... maybe.



I used West Coast Fiero mounts for the transmission in all my swaps - stock rubber ones will fail quickly. This is my 3rd iteration of 4.9 swap and I've done the motor mounts different each time. The best in my opinion is to fabricate front and rear motor mount brackets to use energy suspension RWD trans mounts - you end up poly mounts in all 4 corners and don't need a dog bone. The rear motor mount is the most challenging. In two of my swaps I turned the L bracket from the stock V6 mount under the crank and used stock mount there. The front motor mount is the easiest to make if you have a welder - I attached a couple pics. This one I used gussets, the previous was boxed out - they both great with the stock Caddy bracket. If you are going to fab a rear motor mount, grab one off a 90-93 El Dorado. Well, that is if you use the 4t60 trans. You said you have a 4 speed, unless you luv manuals I definitely recommend the auto - with stock gears it purrs on the highway.

Good luck with the swap, let me know if you have any more questions.


[This message has been edited by 81 4.9L X-11 (edited 07-04-2025).]

81 4.9L X-11 JUL 04, 09:32 AM
Did a quick edit:

Don't buy the FAST GM HEI Coil In Cap Conversion Kits 730-0590 - the brass button for the cap was a pile of shavings in less than 1,000 miles. I'm working on a stainless option and will post when done.



Spadesluck JUL 06, 09:55 AM
Great work! How does it run WOT?
psquare75 JUL 07, 09:06 PM

quote
Originally posted by 81 4.9L X-11:


I used West Coast Fiero mounts for the transmission in all my swaps - stock rubber ones will fail quickly. This is my 3rd iteration of 4.9 swap and I've done the motor mounts different each time. The best in my opinion is to fabricate front and rear motor mount brackets to use energy suspension RWD trans mounts - you end up poly mounts in all 4 corners and don't need a dog bone. The rear motor mount is the most challenging. In two of my swaps I turned the L bracket from the stock V6 mount under the crank and used stock mount there. The front motor mount is the easiest to make if you have a welder - I attached a couple pics. This one I used gussets, the previous was boxed out - they both great with the stock Caddy bracket. If you are going to fab a rear motor mount, grab one off a 90-93 El Dorado. Well, that is if you use the 4t60 trans. You said you have a 4 speed, unless you luv manuals I definitely recommend the auto - with stock gears it purrs on the highway.

Good luck with the swap, let me know if you have any more questions.







Thanks. I'm sure I'll pick your brain as I go along.. I have a partially complete takeout from a 93 Eldorado with 60K miles. Looks like I need different exhaust manifolds because mine both dump down the 'sides' of the engine. I need a conventional crossover setup like every other GM FWD.

I have injector holes I need to do something too, that it looks like you don't have?

I have a 4spd from an 81 Skylark which should be numerically lower than a Fiero (or an X11). Should be around 2500 @ 75 MPH or so.

One tough part about living in Massachusetts, all this stuff is long gone.

I

81 4.9L X-11 JUL 09, 08:19 PM

quote
Originally posted by Spadesluck:

Great work! How does it run WOT?



It runs great and revs out without issue, I haven't truly beat on it yet but can tell it wants more timing on the top end. I'm working on a low buck knock sensor setup to toggle spark retard via the NOS input on the Aces unit - will give me more confidence to chase the higher end performance.
81 4.9L X-11 JUL 09, 08:37 PM

quote
Originally posted by psquare75:


Thanks. I'm sure I'll pick your brain as I go along.. I have a partially complete takeout from a 93 Eldorado with 60K miles. Looks like I need different exhaust manifolds because mine both dump down the 'sides' of the engine. I need a conventional crossover setup like every other GM FWD.

I have injector holes I need to do something too, that it looks like you don't have?

I have a 4spd from an 81 Skylark which should be numerically lower than a Fiero (or an X11). Should be around 2500 @ 75 MPH or so.

One tough part about living in Massachusetts, all this stuff is long gone.



If you want wrap around exhaust you'll have to get it off a Deville - I've heard the 4.1 front manifold actually flows better than later years, but the Caddy motors aren't at a power level to make a substantial difference.

For your injector holes, 2 straight forward options depending on how you want it to look.
1 - leave the Eldo fuel rail and injectors installed and not worry about/ confuse people at car shows.
2 - get an intake off and 80s 4.5 Caddy, mine is from an 88 Deville - but there is a catch, they use different valve covers. The multiport intakes have covers that inset for the injectors and won't work on the TBI Caddy intake so you'll have to get valve covers to match the intake. If you wanna be super trick, use the holes for nitrous or you can go the get it done route and JB Weld dimes in the holes..!!

Let me know how you make out.
psquare75 JUL 28, 12:59 AM
So I see Aces actually makes an MPFI universal setup. I wonder if that could run the 4.9 if I used a 'chevy' style TBI unit without any injectors. You used a factory 4.1/4.5 distributor with the Aces you installed, and the aces works with it? I'd be very interested in reading how you wired that. It looks like the 4.9 7 pin setup is useless with aces/holley, but if I can use a 4.1/4.5 setup, I'll go grab used one.

FWIW I've done a couple of Snipers and a old "terminator" setup (before they were snipers) on my F100, but the price of the aces makes it very attractive.

working on mounts right now, nothing to see really, just a Turbo 400 mount under the engine so far. I did start a tiktok for this thing for laughs.

https://www.tiktok.com/@psq.../7523340853029457207
Dennis LaGrua AUG 07, 07:40 AM
Have been following this thread closely. There's a lot of good info here for people looking to do or have done a 4.9 liter engine in their Fiero. While the Aces EFI will do the job most Fiero swaps use the stock 2240 ECM. The Cadillac 4.9 liter V8 Fiero swap maybe a bit dated but I believe it's still a good engine. It's lightweight, fits great, has loads of low end torque and it gets pretty decent highway mileage. I chose this engine on my convertible project because it's a very good engine for hwy cruising and fun driving around town. .
With the right software editor you can shut off the VATS and do a pretty decent job of tuning the engine and transmission but on the electronic side you're already committed. so I assume the ACES EFI self adjusting quality was the reason you used it. Some swipes have also added a camshaft but the red line stays the same so I left that alone as to not affect the gas mileage.

------------------
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"THE COLUSSUS"
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81 4.9L X-11 AUG 07, 05:07 PM

quote
Originally posted by psquare75:

So I see Aces actually makes an MPFI universal setup. I wonder if that could run the 4.9 if I used a 'chevy' style TBI unit without any injectors. You used a factory 4.1/4.5 distributor with the Aces you installed, and the aces works with it? I'd be very interested in reading how you wired that. It looks like the 4.9 7 pin setup is useless with aces/holley, but if I can use a 4.1/4.5 setup, I'll go grab used one.

FWIW I've done a couple of Snipers and a old "terminator" setup (before they were snipers) on my F100, but the price of the aces makes it very attractive.

working on mounts right now, nothing to see really, just a Turbo 400 mount under the engine so far. I did start a tiktok for this thing for laughs.

https://www.tiktok.com/@psq.../7523340853029457207




I've been looking into the universal sequential port systems (Wild card and Joker) because I really want to use them with their trans controller for custom Cam and turbo mods, but there is a hurdle - Aces uses a 7 + 1 hall effect sensor to correlate cam timing to fire sequential port injectors. Short answer: the MPFI kits won't work with an HEI - I used a vaccum HEI with the TBI kit and it works ok, but is much better giving timing control to the Aces ecm. For the TBI setup, you just wire the two magnetic pickup wires from the distributor and set timing - then you can have ECM fire the HEI coil, but I would recommend you use the Aces coil and convert to remote mount. I'll post and update soon, but I figured out a remote setup for less than $10 in hardware plus a plug wire. Also, you can use any year 4.x distributor - I initially used a 4.5 because it was better suited to convert to vaccum advance, but then found it wasn't necessary, it runs much better feeding magnetic pick up to the ecm.

I talked to Aces about modifying a distributor to work with the Caddy motors, but won't happen for awhile if they do. I'm not sure there's enough market for them to offer a dedicated distributor, so I'm looking to modify a Ford distributor or if needed cut and weld 2 different ones together. That's how I got an LT1 PCM to run my modified 4.9 - welded an Opti spark onto the HEI and used a Coil per cylinder conversion kit to run LS coils.

I know its a ways out, but would be great if you have it done and can join the X-bodies at Carlisle next June.