CERV I Hobby Horse Prototype Fuel Injection Unit

[Bob B.]

Hi all,

Just wanted to share before and after pics of the FI unit I am nearly done restoring. There is one glaring difference between the before and after pics that has nothing to do with restoring it. Can anyone tell?

The unit was developed by Lou Cuttitta in Duntov's group for testing on the CERV I. You won't be surprised that it is called the Hobby Horse, nor that the plenum is referred to as the "mailbox." A lot of modifications of a '57 7800 FI unit allowed the Hobby Horse to generate 350 HP from a 283 engine!

Both the CERV I and the final version of the Hobby Horse developed from this prototype are in the Mike Yager "My Garage" museum.

Bob

[Don H.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

The air meter flipped sides?

[Ed S.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

Seems like the entire FI unit is mounted 180 out in the second pic. The unit is oriented the same way in the pic but the thermostat goose neck is on the other end - or should I say it appears that the intake manifold is flipped around.

[Mike E.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

The air meter flipped sides?

Seems like the entire FI unit is mounted 180 out in the second pic. The unit is oriented the same way in the pic but the thermostat goose neck is on the other end - or should I say it appears that the intake manifold is flipped around.

I think you guys nailed it. Here is vintage photo of the CERV I FI unit.



Mike

[Stuart F.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

Looks like they used individual air vent filters on each metering block - appear to be like fuel filter cartridges. I made up a similar filter on a vacuum advance emissions control switch (forgot what they called that junk) used on a 72 Nova SS I once had. It replaced a small foam filter that in time went back to nature (rots). Very interesting unit.

Stu Fox

[Bob B.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

Hi all,

Yes, no biggie, but a previous owner must have taken the FI unit off the intake and flipped it when he put it back on. Mike's pic is of the unit of which mine is the prototype. As his picture shows, the air meter faces to the rear. When the body was on the CERV, a cover went over the unit with a forward facing air scoop on each side that forced air to the air meter.

You can see the air filters on the metering block in Mike's pic also except they face inward from each end. On the usual FI setup, a vacuum hose goes from the metering blocks to the air meter.

Based on that my air filters are somewhat dirty, it's appears that air went in, as opposed to out. Either way, I'm assuming that this helped equalize air flow to the cylinders and got a net horsepower gain?

Bob

[John D.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

Hi Bob, You are doing a very nice restoration. Looking great. Like we discussed you have a '4800 unit.
Now for a question for you and the gang here. Wonder why the air meter is in the rear?? How does the air meter gets it's air compared to it being on the side or in the front.
In the '90's or so GM produced the Ram Jet engine. They put the air meter aka throttle body in the "front"! JD

[Philip A.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

Hi Bob, You are doing a very nice restoration. Looking great. Like we discussed you have a '4800 unit.
Now for a question for you and the gang here. Wonder why the air meter is in the rear?? How does the air meter gets it's air compared to it being on the side or in the front.
In the '90's or so GM produced the Ram Jet engine. They put the air meter aka throttle body in the "front"! JD

I am no expert but would guess that the only logical reason for the air meter to be located in the rear may be for some "cowl" effect like cowl induction

[Bob B.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

John & Philip,

Here is a pic of the CERV I I got off the internet. The unit was under a cover. The part of the cover behind Zora has a pad to protect the driver's head. With the engine being in the rear, the air meter would be hitting the driver's head if it faced forward. As you see, the cover has a forward facing scoop on each side that forces air to the immediately adjacent air meter. From what I see in pictures, and based on disassembling the air meter and having to clean a thick layer of dirt off off the butterfly and surrounding insides, no air cleaner was used.

John, thanks for your nice comment!

Bob

[Philip A.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

John & Philip,

Here is a pic of the CERV I I got off the internet. The unit was under a cover. The part of the cover behind Zora has a pad to protect the driver's head. With the engine being in the rear, the air meter would be hitting the driver's head if it faced forward. As you see, the cover has a forward facing scoop on each side that forces air to the immediately adjacent air meter. From what I see in pictures, and based on disassembling the air meter and having to clean a thick layer of dirt off off the butterfly and surrounding insides, no air cleaner was used.

John, thanks for your nice comment!

Bob

Based on the photo, I would presume the cover is closed in the rear. Air would enter the sides and get compressed on the closed back wall of the cover, making it more dense. That was the principle behind cowl induction.

[Stuart F.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

Actually, the position of the air meter on the standard production units (on the side) did have some considerations for, of all things, sound! At least that was what I read was Ford's consideration on there later units. Apparently there is said to be a more "throaty" sound on the side that owners like. I would have thought it was for throttle linkage concerns in the days before the use of cables or electrics.

Stu Fox

[David B.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

Lou Built a number of those units. I had one installed on a B/gas dragster I built and ran in the very early 60,s. Another one was on what I vaguely remember was a very strong running butt ugly chevy powered early 50,s Plymouth that consistently cleaned clock at Detroit Dragway. That's where I got the idea to try one. I recall the air meter was installed facing forward on both units. Lou Cuttitta was a genius and very instrumental along with John Dolza in developing the early fuel injection units. Both guys have never received full credit for their accomplishments. I eventually switched to a hilborn set up and can not remember what happened to the Cuttitta set up.

[Bob B.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

David,

Since you raced at the Detroit Dragway, take a look at my '57 Corvette BM/SP drag race car. I have zero documentation on it, but it had been in Michigan since the early 1970s before I bought it. Do you recognize it?

Thanks,

Bob

[Stuart F.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

Dave;

See posts 5 and 6 as reference, and look at most any Fuelie unit and you will see these vents connected to the air meter with tubing and hoses. Believe there also was some clearer explanations in some of the other posts in this thread from the Fuelie experts.

Stu Fox

[Jim L.]

Re: CERV I Hobby Horse Prototype Fuel Injection Unit

Very nice work. Thanks for sharing. There's so much history in this hobby.
I have a question. What are the little filters on the injector blocks?

Thanks.

Approximately 40% of the air ingested by the engine at idle enters the engine via those passages in the nozzle blocks. The filters serve to ensure the air is clean.

Now, having said that, the fuel metering accuracy of the FI unit at idle and just off idle is better when the source of the nozzle block air is from the bottom of the air meter at the 3/4" dia connection normally present. On this unit, that connection would have been that dark, circular area partially obscured by the throttle return spring. Clearly there would be logistical difficulties drawing idle air from this port on this unit. But the unit would work better if using that port were possible.

Jim