Curious , what Rpm's @ Idle ? 1,200 ish ... Another way to make Mfi more Street Friendly is to decrease spool valve movement / opening, rotation to gas pedal ratio, & also changing Barrel/ spool valve to ****erfly's ratio.. On pretty much all MFI blade opening of 0.100 inch , Engine Rpm's 4,000 plus. There are many ways to hide/make cleaner hard to spot Efi in Old Mfi units just do your search & think ... Will cut expensive labor .. On Efi the injectors can be hidden almost any where out of sight using fuel Spider's & other ways
Best running at idle right around 1000 to 1100. Still has good response. A/f around 11 to one. I know fat, but it likes it there. If I remember right that was with a modified 77 or 71 spool. I did play with spool to ****erfly ratios as well.
I’ve thought about something like this so that the Hilborn manifold is not modified in any way. The injectors would be hidden in the air filter box, and only a wire bundle would be visible. Use the pipe threaded injector holes to get vacuum signal lines, again no modifications required to the manifold. Make a replacement insert for the spool and use that for throttle position. RPM signal from an MSD distributor. Then get one of you young guys who are computer literate and efi experts to make it work! Otherwise it stays like this This was 1976, short ram tubes and the first cam. Later it had the 11 inch tubes and a for the era, radical roller cam, and angle milled 492 casting heads. 14:1 compression.
I looked for a MFI fuel curve, but found this. https://mficalc.com/pro/help/examples/ Lots of good info, and of course there are other pages. EDIT: the guy behind this site has a 50 dollar book High Horsepower Tuning For MFI. It has the table of contents on the book page. It has appendix 11, 4 pages for gasoline on the street while the book has over 150 pages. I would hazard a guess it tries to dissuade street use for all but the most dogged. https://racecarbook.com/new-shop/high-horsepower-tuning-for-mechancial-fuel-injection/ I will mention Occam's Razor https://en.wikipedia.org/wiki/Occam's_razor is the problem-solving principle that recommends searching for explanations constructed with the smallest possible set of elements. in 2 different ways. First, MFI is the absolute minimum to fuel an engine under limited conditions. So it meets the principle. Second, you and many others want the old school look and simplicity of MFI on the street. It would stand to reason that it has been done to varying degrees of success over the past 6 decades. It would also stand to reason that if there was a simple, economically viable setup that would work there would be a profitable business supplying this need. There would be a line of happy customers at each big gathering who would say the setup works and they are happy. The fact that this is not the case shows that the people who have done the work and understand the system's benefits and limitations also know that there isn't an off the shelf group of components to ***emble into a consumer usable product. So the principle says that if nobody can sell you a complete ready to bolt on system, it has not or cannot be found. I have been around cars for many years. I have been on a drag team that used MFI (alcohol). I have read a ton of magazines. In my memory, the closest article I have seen talking about the actual parts and tune for running MFI on the street is when Chris ****era built his Camaro. Considering how many 500 Horse SBC or SBC for Under a Thousand Dollars articles there have been there is ONE How To MFI on the Street article. Note it does not have a handy parts list! https://www.hotrod.com/how-to/getting-mechanical-on-the-street Here is a different perspective. This is how car manufacturers did MFI. https://www.roadandtrack.com/car-culture/a45876019/mechanical-fuel-injection-explained/ Can you devise a system that will work? Yes, BUT it will have limitations and trade-offs that you must understand and live with. Be realistic in the operating conditions you will use, try to select components that will complement this induction and be aware of situations that may cause mechanical failure and avoid them.
It’s the dreamer in all of us that goes on these flights of fancy, dreaming about pulling up next to the rich kid with his daddy bought hypercar, and blowing him off between traffic lights. In the Rod & Custom article decades ago about the Spaulding roadster, at the end of the article, Spaulding was asked if he could find the car, would he buy it and maybe try to make it street legal. His answer was, to paraphrase him, that he’d rather reminisce about the good old days, and just drive a new BMW.
@Dave G in Gansevoort Believe me, I get it. It looks like nothing else, and they are extremely rare to see on the street, which is another draw. If they were easy to bolt on and run, essentially another 1-800 part, they would be plentiful and less desired. The people who bought the kit would complain about poor air filter choices, MPG, harder priming/cold start and too much maintenance.
I haven't played with EFI in a long time, but from what I've heard, some of the newest systems are self-teaching with just a few input parameters - mostly just air/fuel ratio - and the ECU will do the rest with some driving to tailor the fuel curve to meet the demand of the motor.
The computer game is not what I think is true hotrods. Yes, I’m kind of involved ( make parts in shop ) to the oilpumps in the new promod record at 5.1 sec. No one in promod try get a old early Hemi, so now its 2026 but I like to think you cant paint the stuff gold and its gold but it can be Ok anyway. How fun is it to drive a new car. Well, I’m stubborn. -One said in this thread, did get better than 8 Strombergs and no leaks.. Thanks for all comments ! I still had not get a answer on my system that has re-welded nozzels on inside. Why, common or ?
I have contemplated an electric pill so to speak that adjusts fuel pressure via a OD sensor and controller of some sort. The electric pill could be like a electronic injector plumber to return to tank. I think lowering fuel pressure to go lean would cause some atomization issues but I do think it could be a good tool . I have a dial a jet but have not got far on my street attempt. ( early Hilborn in my avatar on SBC) ID be happy to be able to stay running at the street drags were you go 300 feet on the front straight of a 1/2 mile circle track and keep going back untill your eliminated so your make a p*** ,then drive back around slow then idle in line again over and over a few times if your lucky. I have considered the dial a jet and a electric valve to stay lean at idle or clear out the plugs if it loads up . Alcohol has a wider range you can be off rich and still run OK so much more ability to be drivable with now the issues of running Alcohol. Im on gasoline. I also am no expert by ant stretch .
Those already exist. They are called fuel injectors. This would be akin to using one big giant injector, that feeds a manifold, running to sprayers at each cylinder, or down the blower, byp***ing the excess to the tank. This is close to Throttle Body injection, but with more hardware. A closed-loop system could be built to do this, but it is reinventing the wheel, to a less precise wheel, that reasonably does the same thing.
Hank, if I understand your question right, I think somebody was trying to shoot the fuel at the back of the valve. Some of my hilborn nozzles are right and lefts and then there are straight ones. Nozzles on front side would have V at the bottom of the nozzle, if you look up in the port at the nozzles you have, they should have the end pointing straight at you. I can take pictures if that would help explain it.
I'd agree with this - they were trying to direct the nozzle discharge at the valve . . . maybe it helped, maybe it didn't! LOL
Also in this picture you can see there was a second set of holes somebody put in my injector. The upper set I am using, the lower set nearer to the port I am using for a vacuum source. I was told to use the upper holes for gas and the lower for alcohol. (Closer to the valve). The upper nozzles have deflectors, V in the end of the nozzle, the lower set would use straight nozzles.
Like Flatrod said, my setup uses the nozzles with the deflection tip. The nozzles are on the outside of the throttle bodies, and are right and left handed, to make sure the fuel doesn’t squirt in the wrong direction. Both gasoline and methanol have the deflectors. Gas nozzles for a 350 are 7s, methanol for the 350 are 20s. This setup only uses a main byp*** (pill), and a pop off on the pump for when you shut off the fuel pump to the barrel valve. Pills for gasoline ranged around 90-110, methanol around 50-60. The main setup difference was in the barrel valve. Initial setup required the barrel valve to leak at idle 10-12%, gasoline, 8-10% methanol. Both idled clean at 950-1150 rpm, and response had no hesitation. What a toy for a 20 year old to play with… yeah that’s young fugly over there in the picture! 1974…
Methanol, 42 degrees advance, no curve, all in fixed magneto. Gasoline, 38 , with 24 crankshaft degrees, 12 magneto, advance curve, all in by 2400 rpm, 14 initial degrees. The best cam for the Valley had 298 degrees intake and 312 degrees exhaust. 550 lift approximately. I don’t remember the specs, lobe separation angle and such. It was a Reed roller cam, probably the third or fourth one he sent us.
The Jalopy Journal
