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Before I buy the ProFlo 4...

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  • Before I buy the ProFlo 4...

    I'm about at the point of switching from the current set up (Powerjection III) on my SBF 331 to the ProFlo 4. A few questions on compatability and if this new system will finally gain some real world driveability.
    Looking at #35940
    Engine is an 11.0:1 SBF331 with a Comp solid-roller cam with .609/.611-inch lift and 242/248 degrees duration at .050 and 2.05/1.60 valves in ported Canfield heads with Scorpion 1.72 roller rockers.
    I have the necessary fuel system components and currently using a Crane (HI-6) ignition box with MSD Blaster 2 coil.
    Assuming I will need to port match the intake but will the injector bung be an isssue? Or just gasket match as best as possible?
    I'm guessing I'll need a different throttle cable bracket since the current one mounts about where the new fuel rails would be.
    Will I be disapointed if this new system doesn't like the size of the camshaft? My current system works OK but long drives, traffic, hot restarts are always a concern.


  • #2
    The #35940 kit uses the #29285 intake manifold - install instructions here: https://edelbrock-instructions-v1.s3...rock/29285.pdf From the instructions, recommended gaskets are either Fel-Pro 1262 or 1262-R which have 2.10" x 1.28" or 2.25" x 1.40" ports respectively so that should give you a reference for size if you know your port size now. The injector holes in the intake ports shouldn't be a problem for port matching. Can't really say what fitment will be with your existing throttle cable bracket but our #8041 bracket works very well.

    Didn't find a specific Comp Cam based on your specs - do you have a part number or know the lobe separation angle? How much idle vacuum do you have now and at what rpm?

    I'm interested in knowing more details about how long drives are a concern for your Powerjection system. Also, what issues do you have with traffic and hot restarts?


    • #3
      Thanks fro the reply Nate,

      Last night I typed up a big ole reply then upon hitting the submit button I was asked to log in again...then it booted me out for too many password attempts...weird. Anyway the cam part # is 35-000-9 but I think that was the number they used for the billet steel cores however the LSA is 110. I think it was their Extreme Energy line back iin the late 2000's when I built the engine. I believe the vacuum was between 9-11'' though I could not find any docummentaion to confirm. I do run power brakes with no issues so guessing it's at an acceptable range.

      The driveability issues are similiar to what one would experience when using a single plane intake with a carburetor on the street, puddling, loading up and the need to "clear it out". There are times while cruising at freeway speeds that it feels like the TPS is unresponsive. It takes a bit of throttle movement to kind of wake it up, then a bit of unlinear acceleration before it feels crisp. After a 10-20 mile run if I encounter traffic, stop and go, etc. the idle becomes inconsistent.Then the occasional popping/backfiring in the exhaust. The idel doesn't hunt, it just decides to pick a different rpm. In fairness to the Powerjection III I never spent a lot of time working on driveability as I was mainly open tracking the car. But the plan now is to make it more liveable on the street and I realize the shortcomings of TBI vs SFI. I would like a system that wouldn't require a clear flood mode after a heat soak everytime it's driven, a system the behaves civil though I can deal with a bit of cam surge and one that I feel confident in taking a race car turned street car out for a nice long drive in the oh so crowded Pacific Northwest.


      • #4
        That LSA is a little on the tight side but if your power brakes work adequately with the cam then you should be okay but you could just take a quick glance at the Powerjection software to see what idle vacuum you have now. I'd say you're probably on the fringe as far as what an "acceptable" cam to use with EFI is but it seems you've managed to get by to this point.

        Sounds like you have many of the typical TBI problems because your fuel introduction point is still basically the same as a carburetor which leads to problems with wall wetting and fuel distribution. And you're right - simply going from TBI to sequential port injection is going to greatly improve on all the little nagging problems you've experienced. I obviously can't really guarantee everything but I think you're in a position to see some great improvements with a Pro-Flo 4 over your current setup.


        • #5
          ProFlo 4 has been ordered!! Thanks again for the information...

          Just need paint the intake black!