TECH: Mechanical Fuel Injection for your SBC...

OK, bare with me here when bringing this old thread to top and asking strange questions. But I have thinking about a Hilborn system a bit the last couple of weeks.

How much can the pills regulate the fuel? Must one change pump, injectors and barrel valve too to be able to tune in different running conditions i.e differnt loads and rpms? What if one found a adjustable valve that would do the pills job? Prefarable a electronic controlled valve, like an injector from a modern EFI system. Do you guys follow me? This injector would just like the pill bleed off excess fuel but instead of being a fixed flow area it will open and close rapidly. Will a Hilborn system be able to cope with all the pressure pulsating this rapid opening and closing af the bleed off valve generates? Or will the fuel metering be badly affected?

If this would work I see no problem for fine tuning a Hilborn to run on the street. It would just require a regular EFI controller, but of course the mapping would be a bit awkward since it would be the bleed off quantity that would be controlled and not the injected quantity.

So the questions would be will a Hilborn system still work with some pulsating pressure in the feed line and will a adjustable bleed off vavel be able to regulate enough to tune the whole load-rpm range? does this make any sense?

What I was thinking was to set the system up and tune it in a regular way but a bit on the rich side maybe. Then just lean it out with this injector valve. This way a malfunction wouldn't damage anything just make it run rich.

//Magnus

 

I realize this is an old thread, but can the phots be restored? Am I the only one who can't see them?

 

While we are digging this up...

Sam, have you talked to 8th grade genius? He drives his blown mechanical injected Willys peek up on the street.

-Abone.

 

Goober,
you beat me to it. Having a surge tank mounted higher than the pump definitely helps a bunch. Years ago on my mate's blown small block Holden Torana we simply made a small rectangular tank out of .063 aluminium (note the Aussie spelling) with a .25" doubler for the float bowl and mounted it behind the core support where the battery used to live before it got banished to the trunk. That put it close to the mechanical pump and somewhat higher so that it gravity fed through a -12 line.
Running on alky it usually took a shot of gas into the Enderle Birdcatcher to get it going initially but once the motor built some heat it would fire right up every time. With a 10-71 blower on an all aluminum small block it ran great on the street and ran in the mid to low 8's at the drags.

Roo Man

 

A "Dial A Jet" by Kinsler works just great for changing conditions ,run a blank (no return) for cold starts and lean it as the engine temp. increases . It is slow reacting depending on the mounting and how much line volume you have ,but it works ! Art Chrisman set up a street driven mechanical system like this. -- We set up an alcohol Hilborn for a 437 CID smallblock in a sand rail and it has run through several drums of alky on a weekend with nary a problem . You just have to make sure it gets clean air and fuel and be sure to put some foam donuts around the nozzle exteriors so dirt doesn't plug the aerators . The spool in the barrel valve is more than an on/off switch ,more like a home rheostat style dimmer switch. It has a groove cut into it's circumference that gets wider and deeper as it is turned in the housing (more fuel as the blades open ) they are specific for the type of fuel used and engine displacement

 

I can't see them either, and I'd be very interested on this subject!
Pictures, pictures!

 

As far as priming...I had a momentary switch for the starter with a seperate switch for the ignition; I simply turned the car over a few times with no ignition, then turned the iginition switch on and it would come to life.

I know this is a basic thing, but, when setting up the injectors make sure you loosen the screws that hold the blades on the shafts and then, while holding the blades in the closed position tighten the screws back up.

 

For those looking to use one of the mechanical systems on the street, it can be done. I've got a 2 3/16 Hilborn setup on a '61 'vette and drive it on the street. There are many limitations but a couple that I will hit on are horrible fuel mileage (no honestly, worse than you are thinking) and no air filters. If the filter doesn't seem like a big deal to you now, wait until you tear apart your engine in the future and look at the cylinder walls. Sure you can rig something up, but then why run the system if it doesn't look like some old school race outfit? For fuel delivery, as Goober and rooman wrote, fuel must be gravity fed into the mechanical fuel pump. That's why the pictures of old race cars had a Moon tank mounted up front. In addition, I use a main tank in the stock position and feed the surge tank with a Mallory electric fuel pump. As far as priming, as long as the mech. pump is gravity fed, it always has fuel sitting on it. They don't need to be primed and are not self priming if they are not gravity fed. I got this information straight from Vern at Fuel Injection Engineering (Hilborn). As retroridesbyrich stated, the easiest way to start is to disable the ingition system, crank the engine over for a few seconds with the barrel valve slightly open to build fuel pressure to the injectors. Then, arm the ignition and light 'er off. Works well for me. By the way, as snap too wrote, a Kinsler Dial-a-Jet works great for different climatic conditions. For mech. injection newbies, the most unusual feature is that the systems don't have any way to respond to air pressure/density changes like a carb can do. When it gets warm you've got to lean out, when cold richen it up. Still want to run them? If anyone has more questions how I did it especially with regard to plumbing I'd be happy to respond. Look at my avatar for a picture.

Joe

 

Here's a pic of our dragster setup, it's not a chev, and not on the street. it is on alky. On the primer pump deal, we run an electric fuel pump, holley, a line from the tank to the elec pump, from there to the nozzle distribution block, a spring loaded toggle on the wheel. If needed, I hit the switch till I hear fuel bubble out the aerated nozzle holders and crank. It works slick. The only time we prime with gas is on first start up, after it's warm it starts on alky fine.

 

Try an EFI controller like megasquirt or something, and use an op-amp with a logic gate added to send out signal when none comes in and vice versa between the EFI controller and the injector drivers. That's my theory... don't know if it'd work.

-bill

 

Yeah that would make sense. Just inverting the signal. That way the acceleration and cold start enrichments would still work. Thanks for the input.

I've been thinink more about this. A Hilborn type constant flow injection system seems to have bad atomization of the fuel. Wouldn't that be even worse at the low fuel flows that you will get at low engine loads? Maybe a lucas or kugefisher mechanical injection system would work better?

//Magnus

 

Ok, how come I cant see the pic's from photobucket ????? I would like see them !!!

 

Because this thread is 3 years old...

 

great post but i agree, if someone can get pics up

 

The description of how the system works mechanically is excellent.
What's missing is what all of these parts lack: they have absolutely no idea what's going on inside the engine except for RPM (and the pump output doesn't match the engine demand for fuel 1:1, but much higher).
There is no input for vacuum, there is no choke, mixture curve, no altitude, air temperature, air density, water temperature, tip-in, power system etc.
After you make an injector, pump size, bypass, barrel valve etc. adjustment the mixture can be fairly close (if you have a vacuum gauge, EGT, wide-band etc.) - but only for that throttle opening, engine speed, vacuum, gear ratio, load, grade, temperature, etc.
When these change, you have to manually input every one of these variables, again...
as you drive.

If not, the mixture is slightly more accurate than pouring gas into the throttles from a sprinkling can, but not much.

If you want to use a mechanical system on the street, it's easier (i.e., only extremely difficult and expensive, but not impossible) to begin with a Bosch from a pre-electronic Mercedes. Then modify every single function in the pump - that's what Ak Miller did with his 300" Ford 6. I heard he almost managed to get it to work after a few years.

Bottom line: don't try this at home.

 

Pictures back for 2009 ??

 

I sent Sam a PM about a year (and a half?) ago. At the time he explained he couldn't find the pics but would continue looking. Never heard after that. I just bought the Dec '79 Hot Rod mentioned elsewhere in this thread. I'll post the info if I can (copyright infringement considerations...) after I receive the mag. At least a summary of the article will appear.

John

 

Well, I just received the Dec '79 Hot Rod mentioned in a previous post. While there is an article about Li'l John Buttera building a hot rod, there is nothing mentioned in that issue about mechanical fuel injection! The rod that Li'l John built in this article uses a 340 Mopar w/webers. Anyone want to buy a copy of Dec '79 Hot Rod? The quest continues...

John

 

Check the same mag for an article on a Camaro. Silver with stripes. That's the engine with the FI.

 

Ahhhh.... I stand corrected! I was looking for a dedicated article to the streeting of a mechanical system. In fact, there are a few paragraphs on the topic. On my way to work now, will read it and post later.

Thanks, RodStRace!

John

 

How about 2010?

 

x's 2

 

ttt