I know they're a P.I.T.A. on the street but I'd fight that S.O.B. tooth and nail just for the look, and be kicking myself in the ass everytime I started it!!! Just goes to show you how F@#$%d up I am!!!
I rebuilt a Lucas unit a few years back as a learning exercise. They are a timed injection unit, which sends pulses of fuel to each cylinder when needed. This is different to the constant flow of a Hilborn/Enderle/McGee/Crower system. The Lucas street units use engine vacuum (via a diaphragm) to change the mixture, unlike the other systems where a pill change is required. The vacuum unit has a mechanical override that acts as a choke, allowing easy cold starts. The Lucas race-only units do away with vacuum system and instead use a simple mechanical cam to change mixture. Cheers, Harv
They are the simplest fuel system I know of . Not super friendly on the street but with a small tank near the front of the car with a Holley float bowl on the side to feed the FI mechanical pump and a fitting for the bypass return. Your stock fuel pump can feed the added small tank or use an electric pump. Once the barrel valve is set and you find the correct bypass “pill” as long as you don’t change elevation to much they're fun.
Nope... I'm Rite There with ya... I will have this, in a flat fender Gayla Jeep! Going to run the mag. Drive, looking For the pump now... It'll be my 3rd blower motor, Other two worked mint on carb's.. Have to do injection, An the it doesn't work... Intrigue's me
I've run MFI on my OT drag racer for more than a dozen years. I had a short flirtation with EFI on it. Being an old school guy, I just didn't wanna learn it. MFI is something I understand. I learned about it long ago, running on a 440 Dodge back in the 80s. My current system is quite complex as it runs eight nozzles on a turbocharged four cylinder engine. It's making just shy of 500hp out of 135 cubic inches. The primary nozzles are small, and I run an idle pressure control valve. This keeps the idle fairly clean. The secondary injectors come in at boost. A boost/pressure regulator allows increased fuel pressure to open the secondary fuel valve, and those nozzles start squirting fuel. Higher fuel pressure with smaller nozzles is a good thing. It's really ALL about the fuel pressure. The nozzle size, coupled with the bypass jet is the pressure control. The higher the pressure at the nozzle, means you get a finer atomized spray rather than fuel just dribbling out. Although I run on methanol, I think my system is as streetable as MFI gets. It rarely ever goes out of tune, but methanol is a very forgiving fuel. The "streetability" is due to the idle pressure control. A lot of guys don't run it or even understand it. The beauty of MFI is the only thing that really screws it up once it is tuned is crap in the system. The fuel pump will lose a bit of efficiency over the long haul. I've made three bypass jet changes in the last ten years. And, the car is consistent. Consistent enough to run only a few hundredths difference on any given day. How many guys with a stick shift car can say that? Another positive is that my son, who currently campaigns the car, is an EFI tech at an aftermarket manufacturer. He is sticking with the mechanical injection and learning about it.
"That is fine for a drag car, but downright terrifying on a road-race car, and nearly impossible to use on the street." Well, I drove this one as my only car for about 4 years and then for another 30 years off and on. I guess I read the same recipe that JD gives -- or figured it out myself. Here's 60 miles up to El Mirage in the 90s. I think it ran better than the cross-ram 6-pot that proceeded it.
The Holley float-bowl trick is a neat one. Good for injection, but also good to provide atmospheric pressure fuel to run motorbike carbs (like Amals... the setup below is for running Amals on a Holden inline 6). Note the rollover valve installed in the filler cap. Apologies for using a shiny aluminum tank... give it a few weeks worth of abuse and it won't look so shiny Cheers, Harv
I hope more people chime in for street use.. I've read several thread's about street use.. There is a lot of info here hiden in thread's
The surge tank is a great addition. But the Holley float bowl makes it unnecessarily complicated. The MFI fuel pump does need a short fat feed hose, and the surge tank accomplishes that. But rather than the float bowl, a sealed tank with a return line from the top back to the main tank works better IMO. This also keep the transfer pump cooler because it's not dead heading, and the fuel is continually run through the filter
Yes. You can use anything for a surge tank. It needs an inlet fitting for the transfer pump to fill it, a return fitting, and the main feed fitting to the injector pump. That one should be big and short. Just put the return at the top of the surge tank. Once the transfer pump fills it, it will simply return the excess to the main tank.
Lots of tech in link below. Here: https://www.google.com/search?q=aug...dcChAQ_AUoAXoECAIQAQ&biw=1280&bih=800&dpr=1.5
I can remember people removing the early corvette injection for the factory dual setup or even the single four setup as most mechanics could not tune the injection setup. The carbs were familiar and often ran better as they were correctly set up.
The Holley tank option , It Only purpose when using a Secondary tank , Holley bowl is so it does not over fill from secondary tank and pump, Main line on primary tank Gravity feeds the mechanical cam or belt driven pump. (Main tank Must be Vented to correct size for main feed line size) MFJ is very simple , But when it comes to ""Street use"" a lot of thought & experimenting to accomplish, It cam be done, but DoNot think its a bolt On & Go , & most will try to adjust all adjustments when cold , Best way is to a-just @ operation temp , because of expansion, Will Run like crap until temp/expansion is reached, Methanol/Alcohol is more forgiving than running Gasoline, ( Air temp , humidity / water grains) Keep Nots
I’ve done it, had a blast- drove it all over one summer. Hell, I even got caught up in s congress traffic on Saturday night at the roundup for an hour and a half one year. It can be a pain in the ass for sure though. It would absolutely shred those Hurst slicks.
I think some basic definition and function may help those learning about mech injection. Please note I am far from an expert and what I have learned is by helping others. 1. MFI as most are discussing here stack injection type is a constant fuel flow. Fuel is proportional to rpm, as the pump is driven off crank or cam and is directly proportional to rpm. 2. The "pill" is a bypass that controls the fuel pressure in the system. You have 8 nozzles and one pill that has a hole that leak the fuel out (under pressure). The nozzles are fixed flow, so to change the air/fuel ratio you put a smaller (higher pressure) or larger (lower pressure) hole in the pill. For more significant changes you have to change all 8 nozzle sizes. 3. The barrel valve is best thought of as a variable flow valve. As the barrel valve opens, it allows more fuel. The ramp in this barrel valve is what is tricky to get set up. Especially for the street. 4. Because the system is constant flow of fuel from the proportional fuel pump at least as far as the basic design, even with the barrel valve having some bit of control over the fuel flow, this makes it hard to get an even air/fuel ratio on the street with varying rpm and vacuum levels. 5. Because of number 4, most fuel injection in racing are basically adjusted for idle and WOT. The mid-throttle range is not of as much concern. However that is where majority of the street driving is done. You can sort of think of MFI as a 2D map of rpm to air/fuel ratio. Whereas sort of think EFI is a 3D map of rpm to air/fuel to vacuum. This isn't exact, but it helps to understand the difficulty of why stack injection type MFI is hard to run on the street. It's 2D in a 3D world. At least that helps me understand the limitations of MFI. Stack injection is a system that works best as a WOT design, with some idle capability. Mid throttle is where it is hard to make it work.
Depending what type of fuel is being used. Gas burns as a vapor so you want the nozzles high on the intake stream so that the droplets can mix with air coming in. On the other hand, Alcohol burns as a liquid and want the nozzles as close to the intake valve as possible It really does not need to mix with the air coming in, the air is just there to fill the void and boost compression
I have been running Rochester fuel injection since 1963......do all my own work, tuning, etc. - on 315 HP 283s, and 375 HP 327s. Rochester is a constant flow system.......nozzles direct fuel into the intake runners above the intake valve. All my Rochesters have been trouble-free for thousands of miles........on non-ethanol gasoline. E-10, E-15, and E-85 will do bad things to these units. I also have modified a mechanical Hilborn injection system for my son's 302 Trans-Am engine. It also is a constant flow system, unlike timed injection for diesels and the new Chev direct injection engine......injection into the cylinders/combustion chamber. My son's car is extremely street-friendly.......very docile around town, but with instant throttle response. It has a custom barrel valve, by-pass start-up electric pump, on-board wide band exhaust gas analyzer, and a Dial-A-Jet (10 pills) for on-board adjustments (not needed often), among a few other bits and pieces I designed and made. We put together a calibration chart that uses ambient temp, humidity, barometric pressure for set-up and weather changes.
I put some real high nozzles on my Bonneville Street Roadster one year. Didn't run any better, maybe a little worse. At high speed it sucked a significant amount of 110 race gas out the top and out the back of the hood. Looked like a pink flame job ready to be ignite. (One run that year.)
Hotrodart , Tell your son,,,,that can’t be done ,,,,,it will cause an uneasy time,,,space ,,,,,out of balance,,,,,the world might end . There are experts here that have adamantly proven it will not work on the street ! So just give up and admit failure,,,,,,and get the universal space wobble joint back in tune . Lol,,,,,,,beautiful hot rod ! Tell your son I am proud of him ! Yes,,,it can work ! Tommy
Thanks.......yes, there are lots of naysayers on this board, but it's really not that hard if you have some engineering knowledge and a modicum of skills. We did all the work ourselves.......zero outside help (except for some elderly guidance......see below). But...he is a "rocket scientist" for NASA........ These guys think they can bolt on a mechanical system right out of the box and do 9 second quarter miles in a 3800 pound car! Well, they all get frustrated when their engine runs like crap and sell off the FI stuff and then claim it can't be done. I got zero help from the drag strip guys......all they know is WOT. It was the roundy-round guys who showed me a few of their "secrets"........what needs to be done to allow for partial throttle and throttle shut down.....setting the butterflies all exactly the same (hot)......and fine tuning for weather conditions......great group of guys.
[QUOTE="hotrodart, post: I also have modified a mechanical Hilborn injection system for my son's 302 Trans-Am engine. It also is a constant flow system, unlike timed injection for diesels and the new Chev direct injection engine......injection into the cylinders/combustion chamber. My son's car is extremely street-friendly.......very docile around town, but with instant throttle response. It has a custom barrel valve, by-pass start-up electric pump, on-board wide band exhaust gas analyzer, and a Dial-A-Jet (10 pills) for on-board adjustments (not needed often), among a few other bits and pieces I designed and made. We put together a calibration chart that uses ambient temp, humidity, barometric pressure [/QUOTE] That the Key Barrel Val spool shape/grind , Can you share or have a pice of the Ramp on spool ? I never used a Hillborn Barrel Valve, is it like a Enderle ( spool) I always used the K style barrel valve with 16-24 nozzles
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