Hello, I purchased a stack fuel injector for my front engine dragster, man i wouldn't have ever been able to put this thing together without this series, great job and thanks.
You are doing great . I am building a 38 Topolino altered with Hilborn FI and a Glide. I raced 60 years ago with Enderle FI but need a refresher. Keep up the good work.
Lots of good info on your videos. I'm not sure if you went over the size of your injectors and cubic inches of the motor. Maybe I missed that. Just curious.
im so glad i finally found good information on mechanical fuel injection. I hadn't been able to find anyone else who could show me what i would actually need to know to set one of these systems up
I always wanted to know the theory behind this system. I am well versed in diesel fuel injection systems. The Cummins P.T. Fuel system uses a barrel valve system very similar to this system. The P.T. System came out in 1954 and it was used thru the 1980,s. You made a very good video showing the theory and hands on portion. Keep up the good work , as my next move is to ditch the tunnel ram an go to mechanical injection. Very helpful info !!
Yes, that is correct. You want to always insure your "reference pressure" (the gauge on the left) is adjusted to 100psi. Otherwise, the measurement you take by reading the right hand gauge means absolutely nothing...
@@digitaloverdrivesystems Great job with your home made tester ! 🇺🇸 when you were explaining turbulence in between the two gauges seems as though you’re gas fitting should be installed next to your second gauge ? Anyway looking forward for your whole series on mechanical injection ! Wish I had the knowledge to convert one to electronic 🤪 👍
Thanks for the reply G. I will do that after I discuss the Main Jet (pill) and High Speed Bypass. Then I'll try to tie it all together and we'll see if it starts...
Thanks for that once again very informative.What’s your opinion on running this mechanical system on the street,I know EFI is the norm now but I like the old school system.Looking forward to part 3
Hello Sergio. It is very tough to get a mechanical injection tuned to a "mid throttle" fuel curve. This system is basically designed for all out racing, either idle plus a little, OR wide open throttle. That being said, it has been done. There was a guy I knew (40+ years ago) that ran one on a 327 on gas in a Camaro. He drove it everywhere. He was our home town version of John Melner from the movie American Graffiti. Cheers friend!
It is all related to the reference pressure and the orifice size. Yes, if the P2 gauge does not read zero, there is a restriction OR the flow rate is too high for the size tubing and lines being used. If the volume of flow is too high, a smaller orifice is required. To compensate for a larger orifice size, the reference pressure can be reduced to get it to zero, but then you have to calculate the leakdown rate and I didn't want to confuse the guys seeing this for the first time. Using 100 psi helps a lot of folks understand the concept much easier... Cheers!
So based on my understanding of your video, the reason for the secondary bypass (idle bypass) would be situations say: 1) In sprint cars, snapping the throttle closed at the end of the straightaway 2) In drag cars, snapping the throttle closed at the end of the run At high RPM - since the fuel pump is creating pressure directly proportional to engine RPM- with the throttle suddenly closed, the excess fuel pressure is bled off through the secondary circuit to avoid dumping too much fuel into the engine on the overrun (kind of like a decel fuel cut in EFI). However, at that point the engine will still be getting the amount of fuel that “leaks” through the barrel valve since an MFI setup is unable to tell whether the throttles are closed because of coasting or idling. Does all of that sound right?
Go watch my Part 3. It explains why you need a idle bypass. Parts 1 and 2 have useful info as well that may help you. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-oEu6jTBrQxY.html
If you are talking about the barrel valve, I was adjusting the hex link between the barrel valve and the master shaft. Shortening it reduced the leakage rate and lengthening it increases it (the % or amount of fuel that leaks to the nozzles). I hope that helps.
@@gibbsey9579 On a carb, the idle speed screw is a stop on the butterfly opening, so you are adjusting the air at idle. On a constant flow injection, the butterflies get set permanently and you adjust the amount of fuel using the barrel valve. So yes, it is similar as you are adjusting the fuel mixture at idle, but they both work a little differently...
I thought you would show the setting on your high speed and low speed pop off valves. My big question is where do you get the 20% from I have heard of every % from 10 to 20 I personally use 12% on my midget and know that the old Offys used 10% but I only have 4cylinders and 1/2 of a 327 small block Not 377. Much smaller engine I guess.
Hi and thanks for the comment. I will talk about the fuel management more in the next vid. BTW, I am no expert on it. My intention is to explain how it works and get guys in the ballpark to set it up. The fine tuning is alot of trial and error I think. Cheers!
Where did you buy that orifice to build a leakdown tester? Brand & part number would really helpout. I have 3 "store bought" testers & every damn one of them test differently
The link is in the description, but here it is again. www.globalindustrial.com/p/261225-orifice?infoParam.campaignId=T9F&gclid=CjwKCAiA_6yfBhBNEiwAkmXy5yC4jZr4wAxV5wMS0C0KH8WpahrpYEAd1lsV2XikGHY5BcY9IbiWfBoCip8QAvD_BwE I have a few extra. If you cannot find one, let me know...
Hello Randy, another great video - thanks. HA - call me 'paranoid' - but I had to cringe when I saw you using your bare hand on 100 PSI air outlet - best NOT to do - just for safety - "Compressed air can penetrate the skin and enter the bloodstream, potentially causing an embolism. This is a condition where a pocket is created by the blast of air inside a blood vessel. Once this pocket of air enters the brain or heart, it can lead to stroke or sudden cardiac arrest. The threshold for skin penetration is around 100 psi (approximately 6.8 bar)." Better to be 'safe than sorry' - use a heavy glove or avoid doing it all together. Again - thanks for the video. CHEERS from AUSTRALIA.
That is partially correct. The idle bypass circuit is out of the equation at ~25% throttle, the barrel valve continues to meter fuel to the injectors at a rate based on the ramp grind on the spool of the barrel valve. I discussed that a little in parts 1 and 3. Cheers!
