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Thread: Cam and Piston help?

  1. #1
    miller19j
    I am looking for advice in selecting a cam and piston combination for my rebuild. Any advice you could provide would be appreciated.
    I currently have a BBC 454 with 119cc oval port heads (Chevy casting number 353049) an Edlebrock Performer RPM intake, Holley 750 carb, and Comp Cams 1.72 roller tip rockers. I am also currently running Log style exhaust because of my engine cover. I might upgrade the exhaust in the future but not this year.
    I was thinking about using a Comp Cams Extreme Marine ( part number 295 112364CL) Cam with a 112 degree lobe sep angle, .547 ex. .544 in (lift with 1.5 rockers) 226 in 236 ex Duration @ .050” This cam is described to be a good cam for a Jet boat wit an A impeller and is good through 1600-5800 RPM range.
    I will be running this in a 19 foot Jet Miller Jet with an A impeller and a freshly rebuilt pump.
    Now to my questions
    Is this a good cam selection and if so what type of pistons should I get?
    If this is not a good cam selection what cam and pistons would you recommend?
    Like I said before any information would be appreciated.
    [ December 21, 2002, 07:52 PM: Message edited by: miller19j ]

  2. #2
    Jordy
    What are you trying to accomplish hp wise? Speed wise? What kind of fuel are you looking to run and what kind of longevity do you want? If you are looking for something to put around the lake but still have a fair amount of get up and go, I'd try to keep the compression ratio between 9:1 and 10:1. SRP makes some really nice little dome top pistons that will get you right in this range, especially with that large of a combustion chamber. With your C/R in that range, you can run pump gas but still run like you're looking to do. Seems like a pretty moderate cam as well. I'd give it a shot.

  3. #3
    Tinkerer
    Do the exhaust first and it will wake up what you have. The engine upgrades wont do much with the log exhaust. The new header exhaust will make more of a change than the engine mods with the log exhaust.

  4. #4
    Blown 472
    If you are going to buy some stuff check out competion products, they are on the web.
    They are in my neck of the woods and seem to have really great prices on chev stuff.

  5. #5
    miller19j
    I guess I left out some important things. I would like to run on Pump gas and I am looking to build as much horsepower as I can and still make the engine reliable and last for some time. The boat is used for a lake cruiser mostly for skiing and pulling the wife on the tube but I also like to make the occasional speed run.
    The logs are staying for now the wife likes the engine cover (so does my insurance agent) and I do not have the budget to redo it to make headers fit under it this year.

  6. #6
    Jordy
    I kinda figured that is what you were looking to do with the setup, so like I said, the cam seems fine as it's not huge, so find some pistons that will get you around 10:1 and you'll be in good shape. Give SRP a look though, they make a sweet piston for not a whole lot of $$$.

  7. #7
    eliminator777
    I hate to add my 2cents worth But the cam you talk has to much lobe center for aa motor with carb. 106 or 108 at most go to chet herbert find the power range you want motor to work 2500to 6000 for a jet boat call them their in anaheim ca. they make the cams and their not that exp.

  8. #8
    77charger
    that cam seems fine for your use.I recomend upgrading to headers to get more from it.You cant go wrong with comp cams either.Compression also has alot to do with the right cam choice.I would say at least 9-1 at min.

  9. #9
    kojac
    I agree with tinkerboater, upgrade the exhaust. I ran that cam in a 460 chevy for a while and it only pulled 4800 rpm' with an a impellar. I hogged out the logged exhaust as much as I could at the neck and got 5000. After Installed the over the trans headers the motor jumped to 5400 rpm's. Pulled the breathers of the valve covers for a test run and got 5500 rpm's. This was on a 20ft merlin day cruiser. wink It's all about breathin in and taken out the air. Look for a set of thru transom headers that breath if you don't want the over the transom type. However don't use the water injected type. they get too hot for under the cover use and could be dangerous. Use the water jacketed headers.

  10. #10
    DUCKY
    Keep your compression at around 9:1, so if you ever get ahold of some bad fuel, it wo't destroy your motor. As Jordy said, SRP makes some nice small dome foged units that are quite reasonable.
    You cam choice looks good for your application, and those lobe centers will allow you to go to O/T headers later without too much danger of reversion.

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