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Fhead Fuel Injection

Discussion in 'Flat Fender Tech' started by pfmg, Jul 24, 2019.

  1. Aug 1, 2019
    pfmg

    pfmg Member

    Billerica Mass
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    Feb 10, 2010
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    255
    Install is done, everything is secured, and seems to be working well. I need to now take it for a couple good rides to log some data, then we will burn a new chip specific to this jeep and the conditions it operated under. Hopefully tomorrow ill get it on the road and have a seat of the pants fell for how things have improved.
    [​IMG]
    [​IMG]
     
  2. Aug 1, 2019
    Jw60

    Jw60 Recovering Jeepaholic

    Sedalia MO.
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    Oct 5, 2018
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    Are you concerned about water dripping into the air filter and into the engine?
     
  3. Aug 2, 2019
    pfmg

    pfmg Member

    Billerica Mass
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    Feb 10, 2010
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    no, its the picture that makes is look like that, should not be an issue. I do have a rain gutter i need to put on there one of these days
     
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  4. Aug 2, 2019
    73 cj5

    73 cj5 Heavy Metal Sponsor

    MS
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    That's slick. I wanted to do this to my f134 but it won't see daily driving or much elevation change so the idea was dismissed.
    How tall is that air filter? 2"?
     
  5. Aug 2, 2019
    pfmg

    pfmg Member

    Billerica Mass
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    Feb 10, 2010
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    yes about 2", with about 1/2 or 3/4" raised base
     
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  6. Aug 2, 2019
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    Oct 3, 2016
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    563
    Nice job! This is a really cool mod. Interested in how the performance changes (and MPG gain). Do you have some downshift areas where you can really test the real-world power improvement?

    A potential future project is a build for my dad. As he's not really a wrench, this is something I've been eyeing.
     
  7. Aug 2, 2019
    Twin2

    Twin2 wasn't me Sponsor 2019 Sponsor

    Virginia Beach, VA
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    needs to be moved to technical index (y)
    for safe keeping . well done
     
  8. Aug 2, 2019
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    Can you explain the distributor mods a little bit? Part #s maybe?
     
  9. Aug 2, 2019
    pfmg

    pfmg Member

    Billerica Mass
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    Feb 10, 2010
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    i had it modified by Hamilton FI, But what he does now that i have it is pretty simple if starting with an aftermarket electronic dist. He takes the advance weights out and fastens it so there is no advance, that is all handled by the ICM-Ignition control module now. he puts both wires from the distr pickup to a connector at plugs into the ICM from what i read you can graft any magnet pickup you can get to work if you have an older points distr you want to use, just takes some effort and maybe some machining, And you CAN NOT use a petronix converted distr.
     
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  10. Aug 2, 2019
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    Oct 3, 2016
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    Very cool. TY! I was looking at the Holley Sniper setup and that can control spark advance as well, so I was definitely interested in how you did your dist. Very cool work!
     
  11. Aug 4, 2019
    pfmg

    pfmg Member

    Billerica Mass
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    Feb 10, 2010
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    Got a couple good drives around town to log some data, now I’ll have a new chip burned and see what improvement we get.. But wow, already it starts better, idles better, and feels like more power . I am now able to climb a couple hills I had trouble with in the past. I’m actually able to power right up them. Very happy with the way it drives, and once I get a new chip based on the data I logged, it should only get better. . Although now my TCase is leaking like a bastard...lol

    I now think my issue before was multiple problems. I know I had fuel delivery issues, and a timing issue, because of those I don’t think the carb was ever dialed in.


     
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  12. Aug 9, 2019
    Muzikp

    Muzikp Sponsor Sponsor

    Sacramento Ca.
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  13. Aug 9, 2019
    gunner

    gunner Member

    Washington state...
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    Bill Hamilton lives not far from me; a few years ago I went by his place to check out his work. He's a IH guy.

    Here's a question for the more technically blessed regards FI: a standard carb can only have a certain size throat to it in order to create the proper vacuum to pull the fuel into the air flow (let me know if I have that wrong). A TBI is set up differently and doesn't need to pull the fuel in- instead it injects it in to create the air/fuel mixture. So the throttle body in a injected system can run a larger area and therefore an increased cfm. Which in turn would lead to more hp, etc.

    I've been wondering about this ever since I became interested in TBI conversions (the reason for my original visit with BH). It seemed that the TBI for the GM 151 (aka the iron duke and the throttle body Bill uses for 4 cylinder apps) consistently had a significantly larger throat to it than a 4 cylinder carb. I eventually plan on going with the 151 system on one of my 153 Nova engines. I've compared both carbs off the 153's to the 151 TBI- there's definitely more CFM potential with the TBI.

    Also 2 of my 153s are marine motors. They run 2 barrel Rochesters- 2GCs. The marine engines are rated at 120 HP while the car 153 (one-barrel carb) is rated at only 90 HP and the only significant difference between the two are the carbs. Marine engines spend their lives at 3500+ RPMs so they can get away with running the greater cfm.
     
    Last edited: Aug 9, 2019
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  14. Aug 9, 2019
    pfmg

    pfmg Member

    Billerica Mass
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    you would think the FI would increase HP a bit, even with everything else the same by optimizing the fuel delivery and spark. I am waiting for a new chip from bill, i have sent him the recent logged data and he made some adjustments, based on my limited knowledge with reading the logs, it the least it was running rich. That said, it is more responsive and as more power than before just based on the feel. But to be fair, my stock setup was never tuned to perfection.

    So the goal now is to get it running as good as possible with the basic setup it has now, just tweaking it after logging the data. After that i'll play with some things, the easiest im thinking will be spark, the stock willy gap is .30, the stock 2.5 GM TBI gap is .60, however on the GM forum, a lot of guys are running them with a .45 gap, for overall better performance, they say the .60 was used by GM for efficiency, not power.

    So with the TBI systems ability to adjust it self, i think im going to try moving spark plug gap up to .40, .45 maybe. Then see how it feels , run some more data and go from there
     
    Last edited: Aug 9, 2019
  15. Aug 9, 2019
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

    Medford Mass USA
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    In theory, EFI should increase horsepower without any improvement in fuel or spark tuning. A carburetor is constrained by the amount of useful vacuum it must produce to power its metering circuits. This requires a smaller venturi and lesser air flow than you can allow with EFI. The computer only uses the engine vacuum as a signal, no longer as a source of power, so the vacuum around WOT can be considerably lower with a throttle body.
     
  16. Aug 9, 2019
    gunner

    gunner Member

    Washington state...
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    Yeah, what he said...:bow:
     
  17. Aug 9, 2019
    Lockman

    Lockman ..... He who dies with the most Tools... Wins ! Sponsor 2019 Sponsor

    White City, NY 14617
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    GM says my Buick 231 V6 turbo Should gap @ .60 also. ALL the guys on the Buick forum are running plug gaps of .28 to .32 . Most of them track race their Grand Nationals. To me it often seems that while this new Tech & engineering is very cool stuff, the old adage of " Keep It Simple " still pertains .
    Take your gap down to .32 and let me know how much you'll dig it !
     
  18. Aug 13, 2019 at 9:13 AM
    pfmg

    pfmg Member

    Billerica Mass
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    Been working on the system, install looks good, seems to work well. Even with a bad tune it still runs better than the carb. But You ask " why do i have a bad tune" because i have probably been giving bad data. I have supplied Bill with a couple sets of data and he has made adjustments, but it really has not changed anything for the better. So i looked into it a little more, and it turns out i should have followed Bills install advice a little closer. He suggests after the install, before you spend any time logging any data, check your fuel pressures. The Inlet needs to be around 13 PSI and the return should be petty much 0. So i put a gauge on it, and my inlet is rock steady at 13, but my return is at 5psi, way too high.
    The excess pressure in the return causes a rich condition at the injector that cannot be tuned out. Any restrictions in the return throws the custom tune way off.
    The good news is i know right were my return problem is, i suspected it would be an issue from install, but still took the easy way. I used the drain on the bottom of the stock tank as the return inlet. The fact that its in the bottom isn't the issue, its because its a small fitting, 1/4" with an even smaller actual hole in it. Otherwise the line from the throttle body to the tank is all 5/16", the recommenced size.
    So i need to find a 90deg 5/16 or even 3/8" bulkhead fitting to install on the top the tank. Then i'll be able to log some good data and go from there.
     
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  19. Aug 13, 2019 at 3:17 PM
    Lockman

    Lockman ..... He who dies with the most Tools... Wins ! Sponsor 2019 Sponsor

    White City, NY 14617
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    Any Fuel return line is for vapor , not raw fuel , by Emission standards. Later Model Vehicles return lines went through a Vapor canister. You should have a return line installed a the TOP of your tank. I believe you should be able to find the fittings you need at your local Hardware Store. We carry many different style brass fittings.
     
  20. Aug 13, 2019 at 4:31 PM
    pfmg

    pfmg Member

    Billerica Mass
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    Feb 10, 2010
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    255
    No, in the TBI system it’s liquid fuel, the system pumps a huge amount of fuel, but only uses what it needs. The return can go anywhere in the tank, side, top or bottom, although bottom isn’t the ideal spot. In the top and side there needs to be a hose or line in the tank to discharge the returned fuel below the fuel level. You do not want it splashing into the fuel, aerating it.
     

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