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SBC 350s - 33ft boat

Old 09-15-2019, 07:17 AM
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Default SBC 350s - 33ft boat

I have an old, heavy Egg Harbor 33ft with sbc 350's in it. What is the normal cruise RPM for these engines?

I took the boat out yesterday and with clean bottom was getting 16mph at 3400rpms. I think the redline of these motors is 4400?
Old 09-15-2019, 08:54 AM
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I think that is about right. Fast cruise would be 3700 about 800 off the top. Is it planning at 16mph?

the one thing that is annoying is getting pushed off plane in rougher seas. Save the higher rpm for that


do they run well , cool, smooth at full throttle? And reach full rpm?
Old 09-15-2019, 09:28 AM
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I have not pushed it to the pins...yet.

But yes, at 3400rpm they were running smooth and all gauges were normal. It was planning at that speed...

thanks for the reply!
Old 09-15-2019, 09:56 AM
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16 mph (knots or mph) seems a little slow for 3400 RPM. I'm guessing yours is a 1970s 33, as the newer 80s boats had big blocks. I would have figured 18 knots at that RPM. I'm not sure there's anything wrong at your speeds if it reaches max RPM and it can comfortably be on plane at that speed.
Old 09-15-2019, 10:00 AM
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3400 is a nice RPM for that motor, maybe a little faster, but not much.
Old 09-15-2019, 10:11 AM
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3400-3600 should be normal.

clean bottom? Props in good shape and clean?

Are they vortec engines? Count the bolts holding the intake manifolds to the heads. If not, could be an easy 35-40 extra HP per side to swap some vortec heads in. More if you have room to swap out the cam
Old 09-15-2019, 10:21 AM
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I had 350 crusaders in my 31' commander. 270hp models, I ran them at 3000 to 3300 rpms most of the time. Running 3300 to 3500 is ideal, any more than 3500 and you are pushing them hard. I cruised at 18knots at 3300, but my boat had a much narrower beam. Prior to this boat I had a 33' alglas (same hull and predecessor to the 33'egg) that boat ran 14knots at 3300 with 240hp chryslers in it so 16 seems about right with your engines. Those are wide, heavy boats and need big blocks to get up and run any faster than 16-18knots.
Old 09-15-2019, 11:15 AM
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1979 model and its a heavy boat! I highly doubt the motors would have vortec heads on it but will check...thanks for the info.
Old 09-15-2019, 05:04 PM
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2 barrel or 4 barrel?
With the 4 barrel (Quadrajet) I always ran on the 2 barrels, about mid 30's , if I went into the secondaries fuel mileage went down but it would haulass.
Old 09-15-2019, 05:07 PM
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4bbls....really curious what it will do on the pins. Probably get .2mpg
Old 09-15-2019, 05:26 PM
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Great boats, but I don't have to tell you that. The 350's were fine for their time, but a little light on cubic inches for that hull - and yes, real thirsty.
Old 09-15-2019, 09:01 PM
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We had a 1980 Egg 33. Those speeds are about what we saw. Anywhere from 16-18 knots at a little over 3000rpm.

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