454 TBI ECU? (Page 1/2)
thesameguy JUN 06, 02:15 PM
Figured lots of folks mess around with GM ECUs, and might be able to point me in the right direction:

I've got a '67 Cadillac Fleetwood Seventy-Five that has turned into a small nightmare. It went from running great in November to not running at all in January and I've got about zero idea why. Since the 429 is mechanically pretty stout, I suspect the ignition or fuel system but my expertise lies strictly with fuel injection and electronic ignition. Carburetors are voodoo boxes as far as I'm concerned.

I've been thinking about buying one of the self-tuning bolt-on EFI systems (FAST, PPI, etc.), but at $2k they seem to be very expensive for what they ultimately offer. Since the carb is a Quadrajet, I gotta believe a TBI system should more or less bolt right up, maybe need a little tuning?

If I were to go hunting for a 454 (I imagine) TBI setup, any coaching on what year or what combination of parts I should be looking for? Any suggestions on how I get a tach signal?

(I realize Megasquirt is also always an option, but my limited experience tells me tweaking a factory system is a lot less work than designing a system from the ground up. Since I'm going for "runs good" and not "ultimate power," I don't think I stand to gain much from MS.)

Thanks!
IROCTAFIERO JUN 06, 04:39 PM
You could probably get by with a 350 TBI setup also, considering that behemoth probably puts out similar power figures (NET)
thesameguy JUN 06, 05:54 PM

quote
Originally posted by IROCTAFIERO:

You could probably get by with a 350 TBI setup also, considering that behemoth probably puts out similar power figures (NET)



That's really a good point. The 429 is rated for 340/500 (IIRC) gross, so probably well within fudge room on 350 parts. I imagine as long as I can hook up TunerPro to it and tweak anything that needs tweaking the source doesn't matter all that much. So, what ECU should I be using?
thesameguy JUN 06, 06:06 PM
Thinking along the 350 lines, perhaps a 1227727/7730 from a 90 - 92 F-body?

I am *completely* new to the world of GM fuel injection, but I think all the concepts make sense. I think that's last iteration of the 3rd gen would still be TBI (pre-LT1) and speed-density (MAP), which would make installation pretty easy. A quick look shows that's mask $8D? And the 7727 is the under-hood version, which would keep wiring short. Lord knows there's plenty of room in that engine bay, even with 7.0l stuff in it.
craigsfiero2007 JUN 06, 07:29 PM
Your Cadillac is the last year they used the 429 engine, it made 340 HP with 480 ft lb Tq. In 1968 they redesigned the V8 into the 472 which made 375 HP with 525 ft lb Tq. If you can find a 472 and swap it into your car, then you can use the fuel injection setup off the 425 made in 1977 as the 425 shares the same architecture with the 472. Unfortunately, these Cadillac engines share very little with the other GM motors. Throttle Bodies also have different mounting patterns than a carb.

Here is some interesting reading for you
http://www.cadillacforums.c...-forum/t-246970.html
thesameguy JUN 06, 07:55 PM
Swapping the motor is not an option for several reasons (not the least of which is if I'm going to do that, an LSx is what's going back in ). Given the abundance of carb->TBI adapter plates out there, I'm not too worried about solving that problem. *Worst* case is I gut the car's throttle plate and use that to bolt on a qjet->TBI adapter, as any standard spread bore q-jet bolts right onto the factory throttle plate. . Double adapters FTW! That would have been required for using a bolt-on EFI system anyway. Also, that page you linked to is my post... notice the same aliases.

[This message has been edited by thesameguy (edited 06-06-2013).]

craigsfiero2007 JUN 08, 08:29 PM
I thought that post had a similar feel to it. LOL! I found this while cruising across eBay.

http://www.ebay.com/itm/54m...em3cd1e19b19&vxp=mtr

Maybe this will work for you. You probably could get a ECU from a 1990 Chevy 454 SS tuned to run it, you might not even have to get it tuned. It sounds like a difficult venture and one that has never been done.
thesameguy JUN 09, 06:05 PM
Wow, that is a great find! The Fleetwood is a spread bore manifold, but it seems if the seller custom makes each one on demand, perhaps he could make one.

What I've learned in the years I've had the Fleetwood is that everyone who owns this vintage Cadillac does one of two things - preserves it totally stock, or doesn't hesitate on swapping in a 472/500 (which makes things easier). Not a lot of tweaked 429s out there, so yeah, this is mostly new ground.

I'm fairly certain that a '60s-era Quadrajet is not the most precise fuel metering device, and even a box-stock TBI system is a close enough match to run the car reasonably well. It's not like I have an emissions system or anything. I'm really keen on buying a (somewhat) running car to pull parts from, but that ebay setup is very tempting - if for no other reason than the guy selling it seems to have a good handle on TBI systems in general. It's fair to put some coin in his pocket to tap a little expertise.
craigsfiero2007 JUN 10, 06:56 PM
I would contact him and see what he can do for you. It looks like he does very quality work. It would be neat if you made your Caddy fuel injected.
thesameguy JUN 11, 12:09 PM
Well, I believe I just sold my Solstice, so now I don't feel bad about bugging him with no near-term intention to buy. I'll bring back the details.