Hey guys new to site. Need some advice, just bought my first boat 18ft dominator with a 383 sbc  edelbrock aluminum heads, victor jr style intake, holley 650dp and jg berkeley pump. Runs great outta water, will rev to 7k with no load. Put her in the water and only revs to 4k and starts to pop and cut out. I have already replaced this so far, fuel pump that is set at 9 psi regulated, new msd hei distributor, new cam, new carb holley 650 with mechanical secondaries, use to have 600 holley vacuum secondaries, please any suggestions will help this is driving me crazy. Thanks


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Small blocks dont have the torque u need for high rpm. Popping what do ur plugs look like could be lean pop

Will take bowl off tomorrow and check impeller and gap and will get back to you guys thanks for input. Probably just gonna end up switching too bbc if I can't figure it out.


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Well... to be honest... a nice built 383 will run fairly good in a lighter small boat... but every one I have worked on typically like a much smaller impeller versus what a big block would like, even comparable hp because of the power band difference and much less torque.

a 475hp small block is going to do it all on the top end higher rpm as compared to a 475 hp big block. With that in mind... most of the small blocks I have come across like no bigger than a "B" cut on some burly nasty built strokers... and most were "C" or smaller. It really depends on where your engine makes it power and what your target rpm is going to be. I'd say, everything else being fine, and your engine is tuned and running properly... you turning 4k and your engine let's say wants to make it's power in the 6k range... I'd venture to say, you're gonna want to start at a "B/C" cut, and more than likely gonna trim it down. Triming more is waaaaay easier than adding it back on.


One thing though... having way to big an impeller won't cause an engine to "pop" or "cut out"... it's will just hit a wall and that will be all she has. You may have something else going on here as well.

Kinda leaning to impeller out at Elsinore right now and she is running 55 at 3900 so I'm sure that has to be a A impeller. What impeller would you guys suggest I'm assuming I'm around 450-475 hp.


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You may have 450 HP at like 6,000RPM, your not making it at 4K, No way in hell.

Your set up sounds like it is having valve issues. What camshaft are you using?

I will assume you had the popping problem before you changed everything out? The motor will not pop if it is simply overloaded, detonate mabye, but not pop.

You don't say if it pops out the carburetor or the exhaust.


Get some manifold vacuum numbers, where the ignition timing tops out and battery voltage while running full out.

Small blocks will work fine, you just need to be a little more on your game.

GT

Power valve?

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Ya that might be it I did replace the cam because I went to do the vavles after 3rd trip and had a bad lobe on number 8. Did you do a leak down test before you pulled motor apart? Might wanna add it was backfiring through carb before I put came in and does not anymore. @ckaz21 did your rev all the way out outta water.


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Well guys just took pump apart to see what she has and it's an A. Measures 7 1/4 across so it's not cut down. Anyone have a B/C or a C?? Looking more toward B/C Or know where I can get this one cut down by weekend?


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Thank will give him a call tomorrow


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I'm out of chino/ pomona


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 Hoping this takes care of it too. For my first boat I definitely got the full dish for the meaning of boat. Lol


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No ran springs that came on the edelbrock heads. I just bought the small kit which was timing chain lifters and cam.


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Well guys no good with impeller. But I did finally get enough ran on motor to really check plugs, she's running real lean. Gonna try a 800dp this coming up Sunday and if no change heads come off and gonna get them checked out. And no more popping just goes to 4k and pretty much hits the wall. And outta water hits 7500 like nothing.


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