1958 Rochester Fuel Injection

[spoon]

Been away for awhile but nearing the completion of the unit. After disassembly and further inspection the unit was actually built for 1958. In the manifold to air meter flange is stamped 1958 unit #4. This appears to be 4th of potential 5 units built.

Rochester Fuel Injection Production Summary

13,289   57-59 Passenger cars and 57-65 Corvettes

544   57-65 Service and training

447   57 Pontiac Bonneville

511   58 Pontiac all models

5 ?   Cadillac

?    Oldsmobile (patents filed

?    Buick (patents filed)

14,791 Total

The distributor and the drive cable have been cleaned up as well as the air meter shown attached in the photo. The only item remaining is the rebuilding of the fuel meter and reinstallation.

[Cadman-iac]

So is the basic unit the same as any of the others, just mounted on a special Cadillac specific manifold?
That's a very rare thing indeed. Do you plan to install and use it on your car? And was it originally on your car? If not,  where did you ever find it?

Very nice! I'd be interested in hearing how it works if you try it. Good luck with it. That's so cool!

Rick

[spoon]

Rick,

The manifold is basically the same as a Pontiac unit that has the Cadillac flanges. I don't plan on installing it on anything because I am really a Chevrolet Corvette guy and have no Cadillacs. I inherited these part from the lead development engineer for Cadillac on fuel systems along with a trove of other pieces. He is still around and I talk to him frequently.
This unit was an engineering piece that was run a vehicle and stored for the past 60+ years.  I have seen one picture of a show car that had FI emblems on the rear quarter. I have attached a few pictures of the unit before I began working on the restoration. You are more than welcome to contact me if you like and can share as much as I know.

Bruce WItherspoon
517 749-4840

[The Tassie Devil(le)]

An interesting piece, and using the distributor drive for injector timing?

Bruce.

[spoon]

I believe the systems are constant flow. They are not synchronized like modernen simultaneous double fire which fires on both the exhaust and intake stroke while modern sequential injection is timed to fire on the intake stroke only. Sequential requires both crank and cam position while SDF only needs crank position. The constant flow requires neither.

[The Tassie Devil(le)]

So, is the drive unit for the fuel pump?

Bruce.

[spoon]

If I understand you question correctly, the distributor drives the fuel meter.

[spoon]

Here is a cut away of a Chevrolet unit

[The Tassie Devil(le)]

Just did a search, and the distributor drive is for the fuel pump, providing up to 200 Psi.

It would be an interesting piece to put onto a 390.  But hood clearance might be a problem in a '59 or '60.

The one you show looks completely different to the other GM ones that I have seen.

Bruce.

[spoon]

Here is a picture of a 1957 Pontiac units for sale on EBAY. If you go out and look at a 1957 Pontiac FI it will have a cover over the top. Here is a link to the cast 1958 Pontiac unit.

https://www.ebay.com/itm/Rare-Complete-1958-Pontiac-Rochester-Injection-w-Distributor-Turkey-Roaster-/223566736837

By the way the units were built in some development vehicles. I put tis next to a tripower manifold with the air cleaner and it is no taller than it.

[Cadman-iac]

Yes, very interesting Bruce, and Bruce. It doesn't look like the typical Rochester injection units that I've seen either.
I've never really looked into how they operated before. A constant flow to each cylinder sounds like a little too much though. I wonder how well it would run. It would be interesting indeed to see it working.
So what are your plans for it? A display piece maybe? If it's for sale,  you can count me out, I doubt I could afford it.
I do have another question,  why are there two distributors?

Rick

[spoon]

A carb is constant flow as well using the vacuum signal to pull the fuel through a jet in a carb upstream of the intake manifold. THe problem. THe fuel does not stay atomized as it travels through the intake runner. The fuel that is not atomized falls out of the air/fuel mixture at low velocity areas of the runner and is no longer used in that combustion stroke. Eventually that raw fuel will make its way to that cylinder causing a rich mixture.
The constant flow systems are metered to deliver the correct fuel in the port atomized as close to a correct air/fuel ratio as possible at the higher pressure to insure that the fuel is actually a vapor and not a drip.
Forgot there is only one distributor. the other is a spare.

[David King (kz78hy)]

Here is a shot of the Eldorado Brougham development that Al Haas gave me.  It looks like it could have been a similar unit and this would have been '55 or '56 as it was before the car was released.

David

[spoon]

Dave,
Not likely that this is the same. The air meter on all of the units, Pontiac and Chevrolet included have horizontal flow into the meter.

[fishnjim]

Museum piece.   Rarity unfortunately doesn't a;ways equate to value.   But glad its in good appreciative hands.
Since U R a "Ch" guy U know the value adder they bring to period factory equipped cars.
I recall since mechanical they were a bit of a pain and therefore didn't capture the buyers.   Seems to be a resurgence of resto FI 50s autos.   Maybe becasue it's so common today, there's a link to the perceived past(?)   Have no idea how well they function after resto with modern parts.
What's more sexy than hearing the tri-power or secondaries kick in on a period HC GM engine?      Like the famous patented HD exhaust.   You don't get that with FI.

ps: The Dev. Eng should be invited to write an article on early fuel development before it's lost to the ages.

[spoon]

I spoke to him last night and he told me to look up the patent because he appears on it. I’ll speak to him and see if I can get him to post on here. He’s a really special guy who spent a lifetime in the industry.

[TJ Hopland]

Did that system have aircraft origins?   I thought I read that is what they were originally developing it for but for what ever reason (maybe jets?) it didn't work out so they went looking for places it worked better and people wanted it.

[spoon]

I can not answer the question about the initial intent of the system for automotive applications but mechanical fuel injection was definitely used on aircraft prior to jets. It was one of the reasons for a performance advantage during the 2nd World War. Some on the fighters were still carbureted which was a limiting factor in their dog fighting during high G maneuvers.     

[bcroe]

The Germans used Fuel Injection on fighter engines, there was even a
diesel aircraft engine used at extreme altitude.  The Allies eventually
did the same on some engines.  I see little written about it, probably
nobody was going to reveal their advantages or lack off, at the time. 

Constant flow might work better on aircraft that always have a big load,
or race engines run near max most of the time.  An advantage would be
the ability to run resonant intake systems, without dropping gobs of fuel
on the way from a single carb, to the cylinders.  The disadvantage being,
pretty hard to get the mixture right stopped at a light.  And I doubt it
could come any where near passing modern emissions regs.  A Wide Band
OX sensor such as I use, might tell quite a story. 

Some EFIs, including throttle body injector types here, did injection every
crank revolution to make it work.  The 70s Cad system port injected every
2 crank revolutions, just after the intake valve closed.  In my 79 the EFI
had far lower emissions than a carb on the same engine.  Power was not
really much different, without a hot cam and resonant runners. 

The basic problem with gasoline fuel injection, is matching the fuel to
the throttled air admitted, over an extreme range of conditions.  It took
EFI to measure the air really accurately, while cranking in corrections for
things like temp, simultaneously adjusting spark timing, with feedback
loops and learning programs that eventually train each system for the
engine it controls.  That view makes those mechanical systems look
really crude.  Bruce Roe

[spoon]

Bruce
The greatest gains with modern fuel injection came primarily from the ability to do two things. Understanding the actual position of the piston during the combustion cycles and the mass density of the air/fuel mixture during those cycles. That said, these benefits were initially done primarily to improve combustion efficiency to make the EPA happy. What it eventually did was allow the reemergence of more volumetric efficient performance. Spending most of my career as a GM development engineer, I saw much of the progression from carburetor to direct injection.