Stock manifold for multi-port EFI

Discussion in 'High Tech for Old Iron' started by Daves72, Apr 14, 2016.

  1. Daves72

    Daves72 I get jokes.

    What do y'all think about using the stock manifold for a multi-port EFI? I'm not looking for massive HP but better drivability.

    My thought was to use MegaSquirt 3 with either a GM 7.4 TBI unit (only 640 cfm) with an adapter plate or perhaps multi-port EFI. This would avoid spending several hundred on a new manifold but I would still have to use some sort of throttle body (not sure what I'd use).

    The popular TBI EFI kits are all pretty expensive so I think using MS3 with an Aeromotive Phantom fuel system would be my approach.

    What do you think?
     
    Last edited: Apr 15, 2016
  2. Ken Warner

    Ken Warner Stand-up Philosopher

    I think if you look at one of the new FiTech EFI systems you will be money ahead and have a much easier go of things. There is an article in THIS forum about them and you can buy direct or look up Fitech on Summit or Jegs.
     
  3. Daves72

    Daves72 I get jokes.

    I will have to check them out but I think I'd like something that's been around a long time like MegaSquirt. Also I'd have much more control over the tuning with MS, unless there's tuning with a laptop you can do with FiTech.


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  4. Daves72

    Daves72 I get jokes.

    Also, I think at some point I will swap to a 4sp transmission like the 4L60E or 4L80E or something similar and the MS3 can control that as well, from what I've read.


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  5. Ken Warner

    Ken Warner Stand-up Philosopher

    Sounds like you know what you want. Bring your engineering hat and credit card and you'll be on your way. Generally speaking they weld bosses to the aluminum intake to hold/seal the injectors. That's gonna be a LOT tougher on a cast iron manifold.
     
  6. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    The 454 TBI may not supply enough fuel for even a moderate 455. The pair of injectors are good to about 300-320HP.

    I have a performer intake I want to use for EFI on my Centurion some day.
     
  7. Daves72

    Daves72 I get jokes.

    What do you think about using one as a throttle body only?
     
  8. DFI STAGE2

    DFI STAGE2 1970 Skylark DFI STAGE 2

    My 2. Buy a self tune throttle body kit. Unless you are looking for complete tune ability. The self tuning kits are way easier for install and drive ability. For most mild builds it's a great option. It's a big expense to have an aluminum manifold prepped for port injection. I would think using cast iron would have to be installed with epoxy. Not sure I'd like that option myself. Good luck with it whichever way you go.
     
  9. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    I could see using the TBI as a throttle body only, within its CFM size limitations. If you find you are pulling vacuum at WOT, you'd want a bigger throttle body.

    I've JB Welded aluminum bungs into a cast iron intake with out too much trouble. I chattered up the iron with my dremel and significantly roughed up the aluminum so the JB Weld had something on each to bite onto.

    In the future, I may try some iron NPT fitting and drill them for injectors to thread into the manifold.
     
  10. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Also brazing in steel bungs would work as well. GL






    Derek
     
  11. Daves72

    Daves72 I get jokes.

    I was messaging with a guy who's an experienced welder and he said brazing was an option also, using either an oxyacetylene torch or a TIG welder for heat. I also came across this EZ Weld TIG wire product that might work too.

    http://youtu.be/V30FelgKb8A


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  12. Daves72

    Daves72 I get jokes.

    I'm think leaning that way. If the TBI turns out to be too small, it wouldn't be a big deal to swap to a larger, 4 barrel TBI....and should be easy to find at a salvage yard. It would also be an option with either the stock manifold or an aftermarket aluminum manifold.
     
  13. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    Honestly, you can just use a carb as a throttle body too. For "best" results you would want to rig up a TPS sensor and idle, or high idle, control valve. I've contemplated using a Q-jet as a throttle body and keeping the stock choke mechanism working, but remove the upper butterfly, just let it hold the throttle linkage open a bit until it warms up. The EFI will add the extra fuel as needed/programmed.


    My test case.

    Here is the intake I installed the aluminum bungs in the cast iron intake. I ALSO used a Holley carburetor body as the throttle body. I had three of them on the shelf, two were essentially junk, so I used one of the junk ones. Just cut some tin plates to block off where the fuel bowls would go, with a healthy dose of sealant to stop vacuum leaks. And since it wasn't moving fuel, I knocked out the venturi's and removed the choke plate. If using a Q-jet I'd consider removing the upper butterflies on the secondaries.

    [​IMG]

    [​IMG]


    This is what I did for a TPS sensor, but Holley does make one specifically to use with their carburetors, or if you get a mid-80's "electronic" Q-jets, it has a built in throttle position sensor. Bonus, also has an electric choke!
    [​IMG]

    This is another option for an idle air control valve. I used a Ford 2-wire valve, common on the 5.0 engine through the 90's, and made a plate to bolt to it and threaded in some barbs. One side goes to the intake manifold or carb base (under the throttle blades) and the other goes to the air filter housing or put its own separate air filter on it.
    [​IMG]

    In my inline six's case, I threaded one end onto a pipe from the intake and ran a hose straight up into the air filter housing. You can see the valve behind the throttle cable bracket.
    [​IMG]


    On the steel bungs, I had difficulty finding ones in steel, but eventually found a guy that will custom make them for a competitive price.
     
  14. Daves72

    Daves72 I get jokes.

    Very nice! Did you use a step bit or regular to drill the manifold? I read about using a carb but the lack of TPS and IAC was making me lean away from that. I'll have to think about it more. The carb that's on the car now is a 750cfm for a 350 and my main gripe is the irregular idle, and the exhaust fumes are terrible. I don't guess any of that would matter if it was converted to a throttle body. The neat part about MegaSquirt is that we can use what ever to provide the inputs that the ECU needs. Good stuff.

    Were you the one who also used an Escort trigger wheel machined out to fit on the crank pulley? I was thinking that's what I would do. I also saw this cool cam position sensor (using the lower half of a GM dist and the upper part of a Ford sensor) on the MS forums.

    http://www.msextra.com/forums/viewtopic.php?f=131&t=51375&start=20

    I called that machine shop last week in Longmont, CO. Hopefully, I can get all the stuff together for them to make one for me also. Thanks for the input. I'll probably want to pick your brain more as I figure this out.




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  15. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    The escort wheel was me and I think it was Dauntless(?) on here just did it for a 350. And remember the Grand National sensors fit the 350 and 430/455's.

    The manifold did not require any special bit. I drilled a pilot hole then followed it up with a bigger bit then used a die grinder to finish the shape. Then JB Welded the injector bung in at the appropriate angle and ground down the bottom part in the port.
    [​IMG]

    [​IMG]

    The fuel rail requires a decent bit. I use a bench drill press and drill a pilot 3/8" bit into the fuel passage, then use a 37/64" bit to widen it out but stop short of going all the way to the fuel passage so the o-ring has a step to sit on. Then take a dremel, some ~600 grit sandpaper and some scotchbrite pads to bevel the edges to ease installation of the o-rings. Takes about an hour to do a rail like this after I have it all measured out. I saw one guy used a cut down metric step bit to create the bevel and steps.
    [​IMG]
     

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