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Hi my name is Mike and I'm new to jet boat forums I'm building a 1974 Miller jet boat 21 ft long we're putting a 454 Big Block Chevy out of a 1984 RV in it I've changed out the oil pump for a high performance oil pump that pumps 25% more than stock I've also taken the heads off port and polished and lapped the valves in I did it at the house so I didn't take it to a machine shop so I don't know anything about the lifters and the cameras stock I pulled the oil pan and use plastic gauge on my main bearing caps and connecting rod bearing caps and the tolerances are good my couple questions are will a 8 quart oil pan be suffice or do I need a 10 quart or a 14 quart? and on my cam do I need a different cam with shorter lobes so I don't get water from my headers down in the motor. Thank u in advance for your help.
 

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Hi my name is Mike and I'm new to jet boat forums I'm building a 1974 Miller jet boat 21 ft long we're putting a 454 Big Block Chevy out of a 1984 RV in it I've changed out the oil pump for a high performance oil pump that pumps 25% more than stock I've also taken the heads off port and polished and lapped the valves in I did it at the house so I didn't take it to a machine shop so I don't know anything about the lifters and the cameras stock I pulled the oil pan and use plastic gauge on my main bearing caps and connecting rod bearing caps and the tolerances are good my couple questions are will a 8 quart oil pan be suffice or do I need a 10 quart or a 14 quart? and on my cam do I need a different cam with shorter lobes so I don't get water from my headers down in the motor. Thank u in advance for your help.
While a "motorhome" engine might last for awhile in a boat, it will not be ideal. Bearing clearances will be tighter than what I would ever accept for a marine engine (others may set them up somewhat tighter or disagree, but I use an old basic set of clearances that have a proven track history).

What does your plastigauge tell you? There was almost certainly no reason for a high volume pump with standard GM factory clearances, as the rod and main bearings are perhaps the biggest "oil leak" an engine has. Melling has a great video on their site showing 4 different bearings with clearances of .001-.004.

Next, the advertised volume of the pan is not always accurate, since you don't want the oil hitting the crankshaft, sometimes a "10 qt" pan works better with only 8 qts in it, to keep from aerating the oil

Lastly, the stock motorhome cam will be plenty small enough to not cause reversion, much more conservative than what you might want to have in the engine to make a little extra power, but with stock 8 or 8.5-1 compression and the tiny truck port heads, your power will still be limited.
 
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