Off the shelf cam options for marine engines
#171
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I guess back to the OP's question. We took off the Chevy square-port heads and "massaged" some 049 big ovals. Changed intake to an oval and matched it to the heads. Bigger valves, tons of headwork.
For the cam we called Comp Cams and they actually (at the time) had an "offshore" program. After a few circular calls thought the system, they had some cam grounds develped that they had been working with offshore engine builders to get the most out of a dedicated offshore motor. To be honest, I don't remember the part number or specs offhand, but I remember we laughed because the "part number" was scribed with a vibro-engraver on the front!.
Sounded awesome, made 507hp naturally aspirated at a 107 VE, nearly 500 f/lb from 2500 rpm on, and fell on it's face at 6400rpm. Super powerful, no. Best boat motors I ever had, yes!
For the cam we called Comp Cams and they actually (at the time) had an "offshore" program. After a few circular calls thought the system, they had some cam grounds develped that they had been working with offshore engine builders to get the most out of a dedicated offshore motor. To be honest, I don't remember the part number or specs offhand, but I remember we laughed because the "part number" was scribed with a vibro-engraver on the front!.
Sounded awesome, made 507hp naturally aspirated at a 107 VE, nearly 500 f/lb from 2500 rpm on, and fell on it's face at 6400rpm. Super powerful, no. Best boat motors I ever had, yes!
#173
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It is refreshing to see this forum has moved away from the monopoly it has been for so long and now there can be a free exchange of information from various other parties.
#174
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Nothing like some validation when back to back dyno testing combos.
#175
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98% of the stuff we do is based on existing lobe profiles. Some of these have been around 30 years or better. The key is to give the engine the right amount of lobe area for the given CID and rpm range. .050" numbers are for marketing cams and don't tell you anything. Being able to see .100, .200, 300 numbers allow you to see what is going on.
We enjoy modern day heads that flow a ton of air quickly. Because of this and relatively low rpm range most boats turn, lift on marine cams don't need to be that large IMO.
#176
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If your breaking tie bars that is tell tale sign your lofting the lifter. Inspecting the elongated slot on the tie-bar during any tear down will show signs of this. In the slot area should be some scuffing towards the end of the bar. Morel uses a stainless alloy for maximum strength to help prevent premature wear.
Johnson lifters. Any input on them? Supposedly bob did a highly scientific test where the johnson lifters outperformed the morels, hence why he supposedly sells the johnsons now.
#177
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Kevin,
98% of the stuff we do is based on existing lobe profiles. Some of these have been around 30 years or better. The key is to give the engine the right amount of lobe area for the given CID and rpm range. .050" numbers are for marketing cams and don't tell you anything. Being able to see .100, .200, 300 numbers allow you to see what is going on.
We enjoy modern day heads that flow a ton of air quickly. Because of this and relatively low rpm range most boats turn, lift on marine cams don't need to be that large IMO.
98% of the stuff we do is based on existing lobe profiles. Some of these have been around 30 years or better. The key is to give the engine the right amount of lobe area for the given CID and rpm range. .050" numbers are for marketing cams and don't tell you anything. Being able to see .100, .200, 300 numbers allow you to see what is going on.
We enjoy modern day heads that flow a ton of air quickly. Because of this and relatively low rpm range most boats turn, lift on marine cams don't need to be that large IMO.
#178
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I was kinda getting ready to yank the motor and go with a custom cam as I hate the feeling of leaving something on the table, but this thread has been very enlightening. It's not that a custom would do me well, but I'll stick with the ZZ502 unit that I've got until I'm ready for a full tear down.
#179
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I was kinda getting ready to yank the motor and go with a custom cam as I hate the feeling of leaving something on the table, but this thread has been very enlightening. It's not that a custom would do me well, but I'll stick with the ZZ502 unit that I've got until I'm ready for a full tear down.
#180
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Too bad we didn't have more time to play....
How about the guy who had a custom specd cam, and gained almost 20hp and lost no torque on a mild 575hp engine by retarding it 4 degrees from its recommended centerline. They really hit the nail on the head on that cam design.
Nothing like some validation when back to back dyno testing combos.
Nothing like some validation when back to back dyno testing combos.