Cadillac Owners Forum banner
40K views 104 replies 17 participants last post by  rdohm 
#1 · (Edited)
I recently bought a '75 Caddy 500 and I am looking for a good way to put an updated FI system on it. Is there a good company that does it or if a company makes an updaed manifold to fit new injectors....Please Help


Thank you in Advance


Check out My Project:
http://www.1953buick.com
 
#27 ·
I just about had one of these. My brother in law replaced the EFI 500 with a carbed one, and had all the EFI stuff hanging around.

But then the ***hole that did the engine swap, and the same one that was responsible for the EFI 500 getting wrecked, threw it all out! All I got was the gold air cleaner lid.

I wanted to do an updated EFI system for a high compression 472, like the one in my '70 Fleetwood. That thing would have been a powerhouse!

Mike
 
#28 ·
Okay, so they do have the gold air cleaner lid. I've seen a couple or three of them on Ebay.

guidematic, that really sucks dude! So your brother in law wrecked your car, then volunteeered to fix it, and replaced the engine with the carbed version, right?

That is really too bad man. You should go pick up that engine and switch them back out lol.
 
#29 ·
Actually it was his car, a 1976 Coupe deVille. He took it to some butcher to have some work done, such as repair those commonly found exhaust manifold bolts. Somehow the idiot got metal into the exhaust ports and it holed a piston.

My brother in law bought a '75 Sedan deVille for parts and the engine, and had this guy put it in his coupe. He even made a mess of that. I spent a whole day working on it so that it was even driveable.

I had been after him for the EFI stuff for some time since he always pondered the idea of putting a carb on it. But when he got the engine replaced, I asked him about the EFI manifold etc, and he went back for it only to find that it all went into a scrap bin, and was hauled off.

Man, that pissed me off. And, my brother in law has been pretty good about spreading the bad word about this guy too. These guys should not be allowed to work on even lawn mowers. Turns out the guy was not even licenced and had no idea what he was doing in the first place. Just some clown that started working out of his garage, then rented an industrial unit. No formal training at all. He knew so little that he said "I can get that fuel injection working, no problem" Little did he know that it was completely differant from anything he as ever messed with. I tried to warn him, but he was so ignorant that he just brushed me off. Now he knows. And it cost him his reputation (what little he had).

Mike
 
#30 ·
Those EFI systems do not lend themselves to modification. All you can really do is change the fuel pressure regulator to an adjustabile unit for a little more pressure across the injectors. You will be limited under full throttle. Even an American Standard Bernoulli porcelain fuel distribution unit will make more power on a modified engine. It won't idle as well as the EFI though!
 
#31 ·
What I wanted to do was to use the ECM, sensors and so forth from a 4.9. I am fully aware that they are completely differant, and the old analog system does not lend itself to any modifications well. Even removing the convertor can affect them.

Also, the firing order is differant, but that can be dealt with by rearranging the injector harness. But, it's the differance in displacement and the spark curve requirements that would pose the greatest challenge.

But, even a system from, say, a Chevrolet Vortec 454 could be set up to work. I would use only the manifold, injectors, fuel rail and other basic hardware. The 1000cfm throttle body would have to be reworked to adapt it to a current TPS and AIC motor and so forth, or a more current large cfm throttle body could be adaped to fit.

This was something that I wanted to play with to see if it could be done without having to mortgage the homestead.

Mike
 
#35 ·
The Ape Man said:
Have you seen the Megasquirt?

You will not be able to drive those old injectors with a modern ECM. Also would need a way to come up with a cam sensor for SFI. Sounds like a great idea though.
I'm reasonably familiar with them, but I'd prefer to try to make this set up work if I could. It's just an idea, though.

If the old injectors don't work, I'd swap them with newer ones. It depends on what the drivers in the ECM are capable of. I know I'd need some sort of a set up for the cam and crank sensor. But, it seems to me they are incorporated into the distributor on the 4.9's. If so, then that would be a reasonably simple swap into the HEI distributor on the 500. But there again, the differant firing orders may prove troublesome.

Mike
 
#44 ·
Ok, there seems to be some misconceptions about fuel injection here. The bottom line is older TBI based systems are offer marginal performance gains if any, and are only marginally efficient against a well tuned carburetor. TBI is only capable of pooping fuel into the broad landscape of the intake just like any regular carb. It is true that with the precision of injectors, the amount of fuel given can rapidly fluctuate (why EFI systems can have better throttle response). Also, with high pressure EFI, fuel can atomize more efficiently. Lastly, air to fuel ratio adjustments on the fly are hard to beat. BUT, let us not forget the nature of these stock TBI systems of this era was for “efficiency” in MPG, not performance, and as noted earlier, the economic gains were marginal.

Where the real-deal EFI comes in is with any MFI (Multi-port Fuel Injection), DPI (Direct Port Injection), CPI (Central Port Injection), or TPI (Tuned Port Injection). The common thing between these systems is “port injection” – meaning all of these systems employ an injector per cylinder ratio. With the understanding that in most cases, many small machines/engines/forces working together are frequently more efficient than one large one, a broad TBI system can be compared to an MFI system.

For reference, three 2bbl carbs were the hot setup back in the day for a few reasons; they administered fuel very well, were efficient at all operating levels for the most part, and had GREAT throttle response since the venturis were small (opposed to fewer large ones). Now, if it weren’t a nightmare to set a small 1bbl carb for each cylinder up, we’d be set (ever see OLD FI systems or multi-carb Hilborn setups?).

The point is you won’t gain much unless you get serious about setting an injector per cylinder rig up. Long story short, I’d get some fuel injector bungs or machine an intake to accept injectors, accept the challenge of setting fuel rails up, and use a universal air-only throttle body with a 4bbl pattern, and hook it all up with an 80’s TPI (or later model LT1) harness with a wildly burned prom accounting for modifications and engine size.

The beauty of a TPI harness is it’s that it’s extremely simple (primitive), yet amazingly efficient. Since the ECM is also “primitive” by today’s standards, it is very easy to “hack” for modifications. On a simple level, I think about any “4bbl” bolt pattern TBI body could be plopped onto any 4bbl carb manifold (or even “2bbl” base TBI setups with a 2-to-4 adapter). I know there are some differences in the manifold bases, but it’d not be hard to change.

Just my input on EFI; I’d say “long live the carb”, but EFI is GREAT when done right :bonkers:
 
#48 ·
Ok, so suppose someone did have a mix and match gm parts bin parts for a TBI setup. I believe it would be very worthwhile, because for the most part here 3 issues have been addressed. Cost, Fuel economy and Performance. Lets not forget a big reason to switch to any kind of efi system....Driveability. EFI car...get in, turn the key car starts in most any weather or altitude. Carbed car...you may have to feather the gas or something to get it started, get the choke to catch, wait for it to warm up before you can go anywhere. Even a simple semi modern TBI setup lets say like 87 or later, you can just get in and go. Reliable when cold or warm at any temperature or altitude. I personally have never been impressed with the power outputs of GM TBI systems but they are very reliable and very simple, a couple injectors, tps, map, o2, cts, all are common and cheap to find or buy. I would not mind a 500 wth a tbi. I guess its cause carbeurators scare me, ive worked heavily with efi being a child of the 80's and having parents who bought only japaneese cars, memories of helping my grandpa troubleshoot some random carb problem and never considering that car reliable cause it wasnt fuel injected. lol.

-The Cadillac Rancher
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top