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Thread: who's running a 383.

  1. #11
    LIBERATOR
    I also run a 385 SBC. Was told by my engine builder to stay away from the Vortec heads. I am using the World Products Torquer 2 cast iron. Was also advised to use a dual plane intake. I am using the Edlebrock Performer RPM. I am curious as to the response by Bruce about the single plane because I trust his judgment. He built my carburator.

  2. #12
    Mike Lindberg
    I know your vortec heads will work fine at 5200 rpm,my friend runs them on his 20 ft. open bow v-hull.He's got a crower cam with .470 and .490 lift,otherwise stock except for holley 750 and aftermarket exhaust manifolds with transom exhaust. he runs high 60's at 5000rpm with a 23"laser.Does you boat have an alpha drive?I also run a 20'v-hull.Its a '92 350 mag.merc.Bravo one.I went the blower route first with a B&M 144,MSD ignition,750 Edelbrock marine,transom exhaust and holley fuel pump.With 4-5 lbs. boost it went from 58 mph to 70 mph. I just finished adding Dart 72 cc chamber heads to lower compression and a Crower cam with .553 lift with 1.6 roller rockers.I'm using a Merc. high five 25 pitch prop,which works the best out of all the props I've tried,might be the small diameter which allows more trim.The motor is going back in this week,I'll let you know how it runs! Regarding your boat,have you thought about a blower? Pacific Power Boats in Portland,OR.has a brand new B&M 250 for $1800 last time I checked.

  3. #13
    Powerplayin
    yup, running a alpha drive with a 1.5 ratio. The boat is 18' and about 3000 lbs. I have enough money in this motor right now... maybe next year I might think about going the blower route.. I will try this motor and see how the boat likes it. I have a spare drive ready when this one grenades LOL!
    Travis

  4. #14
    Mike Lindberg
    Sounds like you're on the right track,I think 5200 rpm with a 23 pitch prop should get you to 70 mph. By the way,I forgot to mention you would have to change your heads to match a blower intake and lower the compression.Good thing you've got an extra Alpha,don't let it come out of the water without letting off! I got my motor in today,just have to check the outdrive alignment.I'm anxious to try out the head and cam change and dial in some timing.

  5. #15
    Powerplayin
    yes, I would have to change the heads to run a blower, maybe next winter, funds are getting low LOL!
    Good luck with your motor Mike. http://free.***boat.net/ubb/wink.gif
    Travis

  6. #16
    BOFH
    Just my opnion, you may want to go back and re-think your overall system.
    If you are going to stay under 5500, you do not "need" forged crank and pistons. Especially, at that low compression... Cast pistons expand more like the block, and you can run a much closer cylinder tolerance, which is free power. This could save money for the same low end power…
    Molly rings are tough to seat. At high RPM/compression they have advantages, but at low RPM they just cost more. :-)
    At low RPM, you have they wrong induction. You need a 180 torque based system, not a high RPM open plenum. Also, I don’t like the Holly off idle stumble. Personally, I would go for Carter AFB (Edlebrock) as they adjust for low RPM better, yet still open up.
    You need to go through and see where you need power, and make the engine breathe well at that point. Too big a head, or carb will actually cost some power, a lot of hole shot, and waste gas and cash.
    You do want to get some rev limiter. MSD has a nice ignition with rev limit possibilities.

  7. #17
    Mike Lindberg
    I aree with the performer intake,and especially the Edelbrock vs. Holley.My Edelbrock 750 has excellent driveability not to mention the linkage and bracket matched up like the weber.I took all the choke assembly off since I'm running a small blower. I bought a new holley on my old boat and never could get rid of the flat spot off idle. Worked great wide open though.

  8. #18
    Infomaniac
    Guys: The off idle stumble with a holley is easily fixed by installing a larger squirter. (The accelerator pump discharge nozzle)You can also drill your existing one if you have a drill set that small.
    It is a common problem with boat use. A boat engine is loaded pretty hard during take off. The accelerator pump has to supplement the engine with fuel momentarily as the main system starts to take over from the idle system

  9. #19
    BOFH
    Holly carbs get the off idle stumble because the secondaries slam open. This kills air velocity, so all the fuel drops out of suspension on the plenum floor. Over drilling the accel jets dumps more fuel to overcome the problem. However, this drop out of fuel is very temperature sensitive, and a drill is not. :-)
    Carter AFBs (Edelbrock) have a vacuum plate over the secondary to block them off at low RPM wide open dumps. This keeps velocity up, and fuel in suspension. As the revs come up, the secondaries come open. :-)
    Both solutions work, but I find the second one more "elegant." What can I say… I like cool toys. :-) Both are good, however. Best to go with what you know.

  10. #20
    Infomaniac
    BOFH We are talking about wide open throttle off idle stumble? That's not what I read.
    If so it is hard enough to get a vacuum secondary Holley to open the secondaries at all much less flop open. Ususlly have to put a lighter spring to fix that.
    A mechanical secondary carb should be a double pumper on a boat and should not have this problem.
    [This message has been edited by Infomaniac (edited March 07, 2002).]

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