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GM Marine Crate Motors from eBay - Missing Low-End Torque?

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Old 10-25-2023 | 07:14 PM
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Default GM Marine Crate Motors from eBay - Missing Low-End Torque?

I ended up purchasing two new 5.7 GM marine crate engines from eBay with a company called Center State Engines.
The engines are installed and running smoothly, we just came up on the 10-hour mark.

The one concern I have is I'm noticing a loss in low-end torque compared with the old engines and my heavy 12,000 lbs 33' 2001 Larson Cabrio cabin cruiser has trouble getting up on plane.
This was never an issue with the original motors (Volvo Penta 5.7 GSi PERF motors, TBI, fresh water cooled).

I'm hoping someone might be able to tell me if the cams used in these new motors are the best ones for my heavy boat.
I'm told the cams in the new motors are: Mercruiser #866022T (Hydraulic Roller, Advertised Duration 196/206, Lift .431/.451) I wasn't provided with the LSA.

I pulled a cam from one of my old motors to read the markings, it reads: 395 FM07 151 00R.
Does anyone know the specs for this cam? I couldn't find much about it on the web.

Thanks for any help.
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Old 10-25-2023 | 08:52 PM
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1st:
your gsi’s have gm vortec heads. Do these purchased motors hsve them too ? If so….you sure GM vortecs ?
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Old 10-25-2023 | 10:05 PM
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Verify your timing is set correctly
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Old 10-26-2023 | 09:03 AM
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TY for the response. I'll check on the heads.
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Old 10-26-2023 | 09:03 AM
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TY for the response. I'll check the timing later today.
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Old 10-26-2023 | 10:11 AM
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The seller says they are Vortec heads.
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Old 10-26-2023 | 11:09 AM
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Originally Posted by prohan007
The seller says they are Vortec heads.
Count number of bolts holding Intake manifold
8 bolts vortec
12 bolts pre-vortec
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Old 10-26-2023 | 11:23 AM
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There are 8 intake manifold bolts.
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Old 10-26-2023 | 12:40 PM
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the fact that you posted a "395" in the cam description triggered my memory.....if this is the same cam, then it comes in the Ramjet 350 and the HT383 crate motors from GM
Specs:

196/206 @ .050,
288/308 adv.
0.431/0.450 lift, with 1.5 rockers
109lsa.
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Old 10-26-2023 | 12:57 PM
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Thanks, Wally for the info.
I thought marine engine applications were supposed to have a 112 LSA to avoid reversion. Is this not a hard and fast rule?
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