EFI

Discussion in 'High Tech Retrofits' started by Slideways, Mar 10, 2020.

  1. Slideways

    Slideways Member

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    Anyone have nice things to say about switching to EFI? I currently have a 427sbc with a 850 Quick Fuel carb on it. Was thinking about switching to a Holley Sniper, motor makes about 9-10” of vacuum at idle.
     
  2. biker

    biker Veteran Member

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    Sniper sure seems to be one of the better ones. Like everything, there will be a percentage of people who will give it a bad review, but those reviews may or may not be valid, because these kits are marketed as DIY, and there are some people installing them who aren't qualified to install a gas cap. I installed the original Holley Pro-Jection 4 on a small block 30 years ago, and various other kits for different people over the years and diagnosed other people's installs. The overwhelming cause of problems that I have seen is people not following instructions or making mistakes on install. Improper fuel supply, vacuum leaks, power supply and grounding are the biggest mistakes.
    So, lots of successful installs and good performance. One common criticism of the Sniper is the touchy pedal and that has been recognized by Holley with some kind of linkage addition that I haven't seen.

    I think your biggest question is what do you want out of it. If you are trying to solve an issue related to your low vacuum, a TBI system may not be ideal, and you may be spending time on the tech hotline and laptop to sort it out. There are some really good multi port systems like the Edelbrock ProFlo 4 that are competitive in price and work better with low vacuum. Multi port also better addresses the issues that are common to both carbs and TBI systems such as heat soak and fuel distribution.
    So, if you are looking to solve driveability issues inherent to carb operating theory, TBI may not be ideal.

    There are also some really good carb specialists here that may be able to help sort out your current setup and save you 2 grand.
     
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  3. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    Couple of us on the site have installed Edelbrock ProFlo 4 setups recently. I have nothing bad to say about it. It cost a bit more on initial purchase but you're getting a multi port system along with the distributor. Also the ECU is stand alone so you can get it out of the heat. I considered Sniper and FiTech but after combing through their forums, I went with Eddy.
     
  4. Slideways

    Slideways Member

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    I really don’t have any drivability issues. It would be nice to not baby it for 10 minutes in the cooler weather. My car does have some minor heat soak issues in the dead of summer, so the EFI I guess is prone to heat soak also?
    The other things I would like to fix: I’d like to get the idle down from 950 to 750-800rpm, when my fans kick on it pulls the rpm down about 150-200rpm. I’d like to control the timing with the ECM, car seems to like it likes lots of timing at idle(think it’s at 18 right now with MSD pro) would need to send the dizzy off to get more initial timing I think?
     
  5. Slideways

    Slideways Member

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    Ooh, and what about RFI noise? I’ve read where some systems are prone to RFI interference from fans, alt, dizzy etc.. is this something that’s a common issue?
     
  6. 76z28

    76z28 Veteran Member

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    I have proflo 3 and haven't had issues.
    I will say the difference is the "new car like" drivability. I can let it sit for weeks and come out and start it like it's a new car.
    It doesn't want to die if I swing too hard into a turn.
    It gets better fuel mileage.
    It makes about the same HP(I couldn't tell a difference between the two).
    It will show any electrical problems you might have.(it amplifies them so you have to fix them).
    It can control fans so I don't have to worry about them.
    I just want to get my computer inside the car, which will be my project this summer I think.
     
  7. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    EFI heat soak issues are generally related to the ECM being heat soaked, not a fuel related issue since an electric pump pressurizes the system. This is mainly with units that have the ECM mounted on the throttle body. That's a huge heat sink mounted on top of a hot engine. In the research I've done, seems the Holley was more prone to RFI. And GM's rear mounted distributor doesn't help the situation.
     
  8. biker

    biker Veteran Member

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    When I mention heat soak with TBI, yes there is the ecu being right on top which is a long term issue, but it is still fighting the same issue as a carb, where it is sending fuel into a hot intake manifold after sitting hot for 20 or so minutes, Yes, the coolant temp sensor will adjust mixture to some extent, but spraying an ethanol mixed fuel into a hot manifold will create the same issues to some degree as u get with a carb. Although, I'm sure it quickly adjusts once running. Whereas, multi port has 8 injectors very close to the intake runner of the head, avoiding much of the manifold heat and distribution issues of TBI.
     
  9. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    the biggest delima is ......the fuel system. Getting fuel from the tank to the motor. There are a few ways of going about it some better than others but that is by far the most PITA part to making an EFI system work on these OLD cars.
    Problem has a bolt on remedy.... $$$$
     
  10. Slideways

    Slideways Member

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    I’d planned on a aftermarket fuel tank from Holley or Aeromotive with the pump in the tank. I have a return style fuel system in the car already with wiring and relays in place.
     

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