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Converting dual quad carbs on 1956 Eldo to single four barrel efi

Started by relentless, May 31, 2017, 10:49:16 PM

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relentless

I have original 1956 Eldo with dual quad carbs, bat wing cleaner (will be selling) am trying to figure out which single four barrel manifold will bolt up so I can convert to EFI system. Any thoughts?

TJ Hopland

Here is good article on historical carb flanges that may help.    Most of the aftermarket stuff is what the article calls Holley.   

edit: guess I should have included the link

http://www.thecarburetorshop.com/Four_barrel_mounting_flanges.htm
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Caddy Wizard

The 56 single manifold should work.  You might need to make (or buy) an adapter plate to fit the EFI unit on the 56 manifold.  But that can be solved.  Same thing for the TV rod -- just be patient and work it out.  I once put EFI on a 1949 (which I probably would never do again).  EFI is a waste of effort on the cars with the 2bbl Carter carbs -- they work incredibly well.  On the other hand, I have had lots of trouble over the years with the 4bbl carbs (whether Rochester or Carter) and can see the value of the EFI on your 56.  The 56 models run darned hot (300hp and the same radiator as the 160hp 1949 engine!) and are fairly prone to vapor lock.  The EFI will eliminate the vapor lock once and for all. 

Here are pictures of my EFI setup on the 49...
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

Caddy Wizard

#3
Those two pictures are while the work was still in process.  Once finished, it was a clean engine look.  Here is the finished product.

Oh, and I hope that I am never foolish enough to add power steering again to a 49.  Now that I have found the skinny tread patch radials that look like bias ply tires, I don't feel any desire to ever add power steering again...
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

bcroe

There are all sorts of EFI systems.  Port injection, throttle body injection.  High
impedance saturated injectors, low impedance peak and hold injectors.  Batch
or sequential injection.  Open or closed loop OX sensor, idle speed, many other
items.  MAP or MAF air sensing.  Electronically mapped spark advance, or not,
knock detector?  Learning systems that adjust to your engine.  Single shaft or
progressive linkage throttle body.  If you understand these and the tradeoffs,
are ready to install fuel pressure and wide band OX sensor gauges, you might
be ready to jump into EFI conversion. 

I have seen some EFI installed, that never ran right.  good luck, Bruce Roe

Caddy Wizard

You can now buy a FI-in-a-box type of system that is really a carb replacement  with all of the sensors (except the O2 sensor) and the brain contained in the carb-like body.  This greatly simplifies the installation.  Several vendors sell them, including Edelbrock.  Prices from $800 to $2000 or so.  Hardest part of the install is the fuel pump (best way is a new fuel tank modified to include an in-tank electric pump).

Here is an example...
https://www.summitracing.com/parts/fif-30003
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

bcroe

A pump unit with a fuel pump mounted can be dropped right into your existing
tank, or an extra tank unit converted to a pump.  This is a better approach than
an external pump, which may have trouble sucking gas when only partially full. 
Pump pressure needs to match the system, which may run 13psi to 40 psi;
volume to cover peak horsepower.  Most EFI requires a return line, which many
older cars do not have. 

Wide band OX sensor gauges for the consumer came out about 2002, and
should be considered essential for setting up EFI.  Get one with a moving
scale; a simple digital readout will be just a bunch of flashing segments for
a fast transitional event.  My advice is get it working on your carb setup first. 
Bruce Roe

Caddy Wizard

#7
Bruce,

Again, I have only done this once.  But it did work out rather well (and that was when the available systems were not as well integrated into a single unit like they are now).  Eventually, in the old car hobby this will be widely seen as an alternative to stock carbs and mechanical fuel pumps on lots of old cars.  Of course, for preservation considerations, this is undesirable and the original fuel system should be restored to the best possible standard, rather than thrown away.  I would always encourage folks to keep 'em stock!

I have always observed that mechanically, the OHV V8 Cadillac engines beginning in 1949 are top of the heap and compare very favorably with any engine of any era in terms of power, smoothness, and reliability.  The weak link in the power train of our old cars is in the peripheral stuff that Cadillac used on the engine (fuel and ignition), which are inferior to what can be put on those engines today.  It doesn't bother me to see someone put a Pertronix, for example, inside the distributor of an original motor.  But I hate to see a perfectly good Cadillac engine replaced with a generic Chevy motor.  That is always a sad sight...

Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

Caddy Wizard

Again, I would never advise this for the cars with the Carter 2bbls.  They just run too well and start too easily, with little propensity for vapor lock.  See the video of my 51 starting from cold...

https://www.youtube.com/watch?v=ZSOc7BrHBr4&feature=youtu.be
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

bcroe

Quote from: Art Gardner  CLC 23021I have always observed that mechanically, the OHV V8 Cadillac engines beginning in 1949 are top of the heap and compare very favorably with any engine of any era in terms of power, smoothness, and reliability.  The weak link in the power train of our old cars is in the peripheral stuff that Cadillac used on the engine (fuel and ignition), which are inferior to what can be put on those engines today.  It doesn't bother me to see someone put a Pertronix, for example, inside the distributor of an original motor.  But I hate to see a perfectly good Cadillac engine replaced with a generic Chevy motor.  That is always a sad sight... 

Right, I am entirely in favor of keeping good quality and useful equipment in
service regardless of age, stuff here spans 1938 to the present.  Instead of
gross replacements, I prefer to address any weak point in the design and
upgrade it if practical.  What I do not favor is throwing parts at a problem
before establishing the exact nature of it.  More gauges help.  Bruce Roe

relentless

Quote from: relentless on May 31, 2017, 10:49:16 PM
I have original 1956 Eldo with dual quad carbs, bat wing cleaner (will be selling) am trying to figure out which single four barrel manifold will bolt up so I can convert to EFI system. Any thoughts?

Been a little distracted with work and other projects but back at this again after purchasing a single quad manifold from seville. pad and holes are just to small for me and I am having a really hard time finding any info on a performance intake manifold to fit my 363 heads.

Fuel pump and pressure pot installed and I am pretty sure all the rest will work ok if I can find a manifold?? Any more thoughts on that one?

Thanks

fishnjim

I'm pretty sure you can get a 2 x 4 FI setup, ie, no manifold change.   It'll be $$$, but check out FITechefi.com
They came out with a 3 x2 also (supposedly) but after I sunk into new carbs/linkage.

TJ Hopland

What style pads are on the manifolds you have now?  I believe that link I gave above has dimensions.

Fuel pump and pressure pot? 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

V63

I put FAST brand EFI on a 57 brougham...very pleased! We did a rail pump, works fine but rather noisy. Car performs like the dual quads! Hooking up the TV rod was a challenge.

YES, they do offer 2 x 4 EFI set ups! Our brougham never had the original 2 x 4 system so above mention not an option.

papas52cad

I found this post in my search for info from those in the know on EFI conversions on caddy’s. I have a 1952 Fleetwood with a 1960 rebuilt 390 engine (16000 miles since rebuild) and related jet away tranny. I would be interested in your thoughts on doing an EFI upgrade on this engine. Currently has a carter 4bbl carb. I have spoken to a local shop who does the conversion using the Holley sniper. I am interested in your thoughts on doing this conversion. My cad has the typical cold start, longs waits between driving, and cold temperature starts that we see here in the North east. It may take 5-7 cranks to get engine to start and running smooth. And it has the typical vapor lock issues when hot, if I don’t have the electric fuel pump on. The car does run well once up and running and then it continues to start up quickly if I have not left car sitting more than a few days.
The local shop has done several over the last 6-8 months with excellent success. . Complete installation Cost is $3100, expensive to say the least. But if it does all they say, I would consider it worth it.
I also read a current post where the FI tech system was installed in FL by a fellow cad owner on his 49 and with good success.
My reasoning is for improved reliability, easy of start and I was told I mileage had improved on some installs (up to 9 mpg! An added bonus if true) The shop states it will eliminate vapor lock as Art confirms above and start ups will be quick, no more pumping gas peddle etc. similar to a modern car. also any thoughts anyone has on the FI tech system vs Holley performance ( $800 vs $1300 for each kit) will be appreciated.
Thanks in advance and Happy holidays to all.
Peter
1952 Fleetwood

35-709

I have not heard of any FI conversions that do not require a 12 volt system, Peter, so you might be looking at more than just the cost of the FI conversion here.  Has your 6v system already been converted to 12v?  If not, consider that in the price also.  You'll be looking at a 12 volt generator and regulator, alternator or possibly an expensive "genernator".  A 12 volt ignition coil, all new light bulbs (replacing those dash lights will be a pain), a reliable 12 to 6 volt resistor for your heater blower motor (or a 12 volt motor out of a '53 might work), and one for your clock if you bother keeping it working.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

TJ Hopland

Fi Tech was apparently started by several guys that worked for some of the big name companies and thought there was a better way.   They were the first to market with the $1000 self contained self learning system which was a big deal because before them you were looking at closer to $3000 and a separate ECU.   When they first hit they were way more successful than they expected so they were constantly back ordered and unable to keep up with support.  That was around 4 years ago.  Since then they have added a ton of other products and hopefully improved their support department.   About a year later Holley came out with the Sniper which was a very similar product to their original GO lineup.   They both seem to be good systems so I would say go with the one that will give you the best support.  If you have a trusted shop that has installed several Snipers and has several satisfied customers I would not hesitate to go with a Sniper.  If the shop did FiTech's or your neighbor did a FiTech then I would do FiTech.   

Vapor lock or at least vapor lock like symptoms are still possible especially with some fuel supply configurations.   The issues if you have them don't tend to be as bad but can still happen.   I had a minor issue with mine due to where I mounted the little fuel pump tank thing.  I originally had mine mounted on the fan shroud.   I know that sound a little odd but the Eldo engine sits off center due to the FWD so it seemed like a pretty good spot.   It wasn't in the direct airflow from the fan and I had heard EFI could never vapor lock so that was where I put it.  My system had some minor bugs that took some time to work through before I got down to what I was suspecting was a vapor lock issue causing rough hot starts.   I shuffled some things around like the horns and got the tank mounted next to the radiator and have not had any symptoms since.

Fuel supply seems to be one of the bigger problem areas for a lot of installs.   The best option is a made for EFI tank and in tank pump.  There is a good reason the factories almost always did it that way, it just works.   If you have a popular older car no problem you can get a new EFI tank.   If they don't make a tank I think its worth taking a look at your tank and whats available to see if there is a new tank available that is close.  A little fab work to make something fit could be well worth it.   IF that isn't an option they do make pump retrofit kits you can add to an existing tank.   They fit a lot of tanks but not a really tall or really flat one.   I also hear mixed things about how well the perform with lower fuel levels.  Factory tanks usually have several baffles to keep fuel from sloshing around which you don't get with a retrofit.  The pump kits have a little bowl that surrounds the pump but its just not as good as a complete factory style system. 

The historic option for retrofit fuel supply was an inline pump.   Until fairly recently it was pretty much the only option.  They have a lot of downsides that you used to just have to live with.    They tend to be noisy which isn't a problem for a 'hot rod' with headers and exhaust cutouts but can be a problem for people with an otherwise stock sounding car.   They tend to have shorter lives because they don't run as cool as in tank ones that are submerged in fuel most of the time.    They can be difficult to get primed because most pumps push way better than they pull.   You think 'I only have to do it once so no big deal'.   Remember above when I was talking about the baffles you don't have?   At least if you have one of those retrofit in tank pumps and the gas sloshed past the pump again it should quickly prime and pump again.   With an inline pump you may have a fairly long run of now possibly empty line that has to get filled again before you get fuel into the pump.   This only sort of works if you get the pump mounted  in the best possible place which isn't always practical.   You can minimize the issues with a good mounting location and by keeping more than a 1/4 tank of fuel or higher all the time.  I did it for several years and it wasn't a huge problem but was sometimes annoying. 

The option that has existed for many years but was only fully DIY is a surge tank or swirl pot.   This is a small tank usually mounded near the engine that is fed by a low pressure pump and contains the high pressure pump.   Some forms of racing have used these for years.   In the last 5 or so years several companies started making them so its now a much easier option to consider.   The low pressure feed can be an OE mechanical pump.  This has a lot of advantages.  You can leave most of the original system in place.   Basically this tank is kinda like a carb bowl.   If you go around a corner and the pickup gets uncovered no problem there is still fuel in the little tank around the high pressure pump and the mechanical pump can pump air and re prime itself easily.   You do have to add a return line from the little tank back to the main tank.  Many people will just tap a line into the filler neck.   Any air that got pumped from going around the corner just gets pushed back to the main tank in the return line along with any excess fuel.   On paper it seems like an ideal solution.   In practice its decent as long as you can get it mounted in a cool location.   The constant flow through the return does help keep it cool but its not as cool as it would be if it was in the tank.    If your choices are inline or this then this wins hands down.   

I believe most of the throttle bodies have built in regulators and return ports.  Some of the surge tanks have regulators and claim you don't need to do a return from the TB.   Some people also go with what is called a Corvette regulator that usually gets mounted closer to the tank and you just run one line to the front.  In my mind this opens you up to vapor lock because the only path for any air is out an injector.  Also means there isn't much flow in the lines most of the time so more chance for heat to build up.    If you do the classic regulator and return setup you have constant flow.       
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

76eldo

All of my Cadillacs are completely stock.

Even on my tri lower cars I have no carb issues.

On my 71 and 7) there is a bog when you try to drive away on a cold engine. After a few mintiest is goes away.

When I get carbs rebuklt I get them done by a local expert.

Complicating and old Cadillac with modern electronics just doesn’t appeal to me. I work with electronics all day long in the security industry and the old low tech design of my cars is part of the appeal.

To each his own.
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

papas52cad

Thank you for your comments and guidance, on the positive side my car was already converted to 12v...
The local shop does the sniper, I have not looked for a FI tech shop, I may do that for competing views and sales pitches, but I already know the good reputation the Holley shop has.
I will have more questions before doing install, especially based on your insight TJ. Many thanks for that info...I have also read that the in tank pump is the best option, not sure what that entails or if the provided sniper kit pump can be placed there. They did mention the need for return line and I will stress the need to do best to totally eliminate the current vapor lock issue.
Given cost, I will do more research and await any addition info thru this forum.
Thanks again
Peter
1952 Fleetwood