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Cam Thread# 10,000

  1. #1
    jetboataholic HawaiianJet's Avatar
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    Question Cam Thread# 10,000

    I'm thinking about putting a cam in my good ol' Chevy 427T, but I don't know what I'm doing when it comes to this. A little info about my boat. The enigine is a 427 truck block that has been bored out .060", I have Bassett OT headers that I run wet, an Edelbrock dual-plane intake manifold, Mallory Marine Point style dizzy, GM Hi-Perf oval port heads, Holley mechanical fuel pump, and a Holly 750 cfm HP series carb that was custom built for my engine. The pump is a Berkeley 12JC with an AB cut impeller and a Place Diverter.

    I found this CompCams Xtreme Marine camshaft that says excellent for jet boats.

    Hydraulic Flat Tappet
    Grind 288, 244*/254* Duration, 570*/.575" Lift

    Is this a good cam? I still want to be able to idle, not be too choppy (loppy?), and run water in my headers.

    What would be the benefits of putting a new cam in my engine, like I said I'm clueless when it comes to this stuff, so school me please.

    Thanks, you guys are the best!

    HJ

    ***FOR SALE*** 1978 19' Full Stringer Hawaiian Molokai Jet Boat w/ Berkeley 12JC-AB and Chevy 440 Tall Deck ***FOR SALE***

    Quote Originally Posted by mako shark mark View Post
    Oh yeah, Forgot to mention that the hull is a special mixture of speedcote, herculiner and rain-x, all blended together- good for another 8 mph top end.

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  3. #2
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    HJ,
    what heads are you running? Size valves? Compression Ratio?

    Might help you decide on a cam.

    Also it is good to talk to one of the Jet boat "gurus", they are more familiar with what works well in a jet than the cam manufacturer.

    I talked to a jet "guru" and then plugged the info into the Desk Top Dyno program, trying all the different cams. I found the one recomended by the "guru" made better power than the ones the cam company called a jet boat cam.

    Also I would suggest you upgrade your distributor to electronic ignition. Points are a pain in the butt and you can install a Pertronics set up for about the cost of two sets of points. More reliable, better spark control and you never have to replace them or set dwell. Of course an MSD would be a plus, but on a budget the Pertronix is an excellent option.

    Doug
    Last edited by Real McCoy; 07-17-2008 at 05:51 AM.

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    jetboataholic HawaiianJet's Avatar
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    Quote Originally Posted by Real McCoy View Post
    HJ,
    what heads are you running? Size valves? Compression Ratio?

    Might help you decide on a cam.

    Also it is good to talk to one of the Jet boat "gurus", they are more familiar with what works well in a jet than the cam manufacturer.

    I talked to a jet "guru" and then plugged the info into the Desk Top Dyno program, trying all the different cams. I found the one recomended by the "guru" made better power than the ones the cam company called a jet boat cam.

    Also I would suggest you upgrade your distributor to electronic ignition. Points are a pain in the butt and you can install a Pertronics set up for about the cost of two sets of points. More reliable, better spark control and you never have to replace them or set dwell. Of course an MSD would be a plus, but on a budget the Pertronix is an excellent option.

    Doug
    Unfortunately, I don't know a lot about the specifics of the engine because I bought it already assembled.

    The heads are GM oval port iron heads that came with the long block I bought, along with the current cam that is in it, which I don't know anything about either. I assume that their both basically factory stock, but it is a marine block, so I don't know. I do know that it has flat top pistons in it, so that will bump the compression up a little bit, right? But that's all I know about them too.

    Don't know if this will help, but the casting number on the heads is 14092359. When I ran the numbers, all it said was 86-90.....oval.....OPEN.....366T, 427T, Marked "HiPerf". The block number is 473478. When I ran it, all it said was 427T.....77-90.....4-bolt.

    Don't know if this helps either, but here's a picture of the heads when I first got the engine, I have not changed anything about them.



    Sorry I don't know much more about my setup. Maybe you guys can figure out more about them than I was able to.

    Thanks.

    HJ

    ***FOR SALE*** 1978 19' Full Stringer Hawaiian Molokai Jet Boat w/ Berkeley 12JC-AB and Chevy 440 Tall Deck ***FOR SALE***

    Quote Originally Posted by mako shark mark View Post
    Oh yeah, Forgot to mention that the hull is a special mixture of speedcote, herculiner and rain-x, all blended together- good for another 8 mph top end.

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    HJ,
    I would hold off at this point in the season and run the boat as is. From the picture the springs have the stock shield around the springs so more then likely you have stock springs on this engine. Also you have the welded ball pushrods which are not condusive to hot rodding as the balls like to come off.

    I would budget now and pull the heads off over the winter. Get them checked out and if the casting are in good shape put some bigger valves in them, bowl bend, and then re-cam along with some rockers and pushrods to build a better top end. At this point putting a cam in it without know details about the heads could lead to a "shortened '08" boating season.

    Just my thoughts...
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW

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    jetboataholic HawaiianJet's Avatar
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    Quote Originally Posted by cstraub View Post
    HJ,
    I would hold off at this point in the season and run the boat as is. From the picture the springs have the stock shield around the springs so more then likely you have stock springs on this engine. Also you have the welded ball pushrods which are not condusive to hot rodding as the balls like to come off.

    I would budget now and pull the heads off over the winter. Get them checked out and if the casting are in good shape put some bigger valves in them, bowl bend, and then re-cam along with some rockers and pushrods to build a better top end. At this point putting a cam in it without know details about the heads could lead to a "shortened '08" boating season.

    Just my thoughts...
    Thanks. I think that that's probably what I'll do.

    But, are these good heads to run with a hotter cam and stuff? Or would I need to get some better aftermarket heads down the road?

    Thanks again.
    HJ

    ***FOR SALE*** 1978 19' Full Stringer Hawaiian Molokai Jet Boat w/ Berkeley 12JC-AB and Chevy 440 Tall Deck ***FOR SALE***

    Quote Originally Posted by mako shark mark View Post
    Oh yeah, Forgot to mention that the hull is a special mixture of speedcote, herculiner and rain-x, all blended together- good for another 8 mph top end.

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    How much power do you want?
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW

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    jetboataholic HawaiianJet's Avatar
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    Quote Originally Posted by cstraub View Post
    How much power do you want?
    500-600 hp would be nice. 650 hp would be even better, but I think it's a little out of reach for right now.

    Someday I'd like to step up to a 502, but that's years down the road, unless I hit the lottery or something.

    Are Dart heads any good?

    Thanks.
    HJ

    ***FOR SALE*** 1978 19' Full Stringer Hawaiian Molokai Jet Boat w/ Berkeley 12JC-AB and Chevy 440 Tall Deck ***FOR SALE***

    Quote Originally Posted by mako shark mark View Post
    Oh yeah, Forgot to mention that the hull is a special mixture of speedcote, herculiner and rain-x, all blended together- good for another 8 mph top end.

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    Quote Originally Posted by HawaiianJet View Post
    500-600 hp would be nice. 650 hp would be even better, but I think it's a little out of reach for right now.

    Someday I'd like to step up to a 502, but that's years down the road, unless I hit the lottery or something.

    Are Dart heads any good?

    Thanks.
    HJ,
    For that type of power you want CID. I would build a 496 out of your TD. With this type of CID and your heads the 600 mark is doable but would take a healthy cam and some compression to do so. The better route for longevity would be an aftermarket head on top of 496 CID.

    You could over the winter put the cubes under those heads and have a good solid 500HP engine. Run it for a couple of years then add heads and camshaft.
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW

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    jetboataholic HawaiianJet's Avatar
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    Quote Originally Posted by cstraub View Post
    HJ,
    For that type of power you want CID. I would build a 496 out of your TD. With this type of CID and your heads the 600 mark is doable but would take a healthy cam and some compression to do so. The better route for longevity would be an aftermarket head on top of 496 CID.

    You could over the winter put the cubes under those heads and have a good solid 500HP engine. Run it for a couple of years then add heads and camshaft.
    How reliable would the 496 be? I'd like to have more power, but still be very reliable and not have to worry about popping it, if I get on it a little too hard. I'm basically looking for "get in and go" horsepower, if this is possible.

    While searching around on the JE website, I went looking for a 496 combo for a 10.180" deck block. But, I could not find one. The smallest cid that I was able to find was PN#131670 a 525 cid combo that uses: 4.310" bore, 4.500" stroke, 6.535" rod length, and 1.395" compression distance. Would this be an even better alternative to a 496? And again, what kind of reliability and longevity would I be looking at? Here's a link to that page.
    JE PISTONS

    And now on to heads, I found this Dart top end kit. Would this be a good set of heads and intake manifold for my engine? Here's the link.
    DART IRON EAGLE TOP END KIT

    Or would it be better to step up to the aluminum version? Here's that link.
    DART PRO 1 ALUMINUM TOP END KIT

    Or if I decide to go the aluminum route, spend the little extra money on the Brodix heads? Here's that link.
    BRODIX BB-2 PLUS TOP END KIT

    Thanks for all your help.

    HJ

    ***FOR SALE*** 1978 19' Full Stringer Hawaiian Molokai Jet Boat w/ Berkeley 12JC-AB and Chevy 440 Tall Deck ***FOR SALE***

    Quote Originally Posted by mako shark mark View Post
    Oh yeah, Forgot to mention that the hull is a special mixture of speedcote, herculiner and rain-x, all blended together- good for another 8 mph top end.

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    HJ,
    By using the CID to make the power it is less stress on the engine combination as the large CID will make power at lower rpms. If your looking at no maintenance at all just jump in and go I would build a 500HP engine. Your looking at getting 200 to 300 hours out of the engine before any major check ups. If you looking for more power then a little maintenance is going to be neccessary so that you don't have any major catastrophys. 600 to 650 is doable but your looking at a good check up between 100 and 150 hours.

    With a tall deck you have more options on rod lengths. What your looking at is the compression height of the piston. A 4.500" stroke in your block will require major clearancing and a stroker oil pan. A 496 with 4.250" is fine for what you want.

    Going Dart or Merlin heads in iron for what you want will work. If you want aluminum heads you can go that route but for what your wanting to do not neccessary.
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW

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    Using a 4.250" stroke crank and a 6.535" rod you can use a piston with a CH of 1.520"
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW

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    jetboataholic HawaiianJet's Avatar
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    Quote Originally Posted by cstraub View Post
    HJ,
    By using the CID to make the power it is less stress on the engine combination as the large CID will make power at lower rpms. If your looking at no maintenance at all just jump in and go I would build a 500HP engine. Your looking at getting 200 to 300 hours out of the engine before any major check ups. If you looking for more power then a little maintenance is going to be neccessary so that you don't have any major catastrophys. 600 to 650 is doable but your looking at a good check up between 100 and 150 hours.

    With a tall deck you have more options on rod lengths. What your looking at is the compression height of the piston. A 4.500" stroke in your block will require major clearancing and a stroker oil pan. A 496 with 4.250" is fine for what you want.

    Going Dart or Merlin heads in iron for what you want will work. If you want aluminum heads you can go that route but for what your wanting to do not neccessary.
    A little maintenance is ok and going through it would be alright too, I just don't want it to come apart on me. Basically, I want longevity. A check up once a year would be just fine with me, it only costs a gasket kit and oil, as long as nothing serious has happened.

    So, for a 496 cid, I could use a 4.250" stroke crank, 6.385" rods, and pistons with a compression distance of 1.670", correct?

    Thanks again.



    Quote Originally Posted by cstraub View Post
    Using a 4.250" stroke crank and a 6.535" rod you can use a piston with a CH of 1.520"
    Sorry I wrote my other post before you typed this one, I am experiencing internet problems so I was just now able to submit it.


    Which is better, longer rod or taller Compression Height?

    Thanks.

    Last edited by HawaiianJet; 10-17-2008 at 10:18 PM.
    HJ

    ***FOR SALE*** 1978 19' Full Stringer Hawaiian Molokai Jet Boat w/ Berkeley 12JC-AB and Chevy 440 Tall Deck ***FOR SALE***

    Quote Originally Posted by mako shark mark View Post
    Oh yeah, Forgot to mention that the hull is a special mixture of speedcote, herculiner and rain-x, all blended together- good for another 8 mph top end.

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    Straub is working good advice and info for ya HJ. Good luck with the upgrades.
    "As democracy is perfected, the office of president represents, more and more closely, the inner soul of the people. On some great and glorious day the plain folks of the land will reach their heart's desire at last and the White House will be adorned by a downright moron."
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    The rest of us are being dragged along kicking and screaming.

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    jetboataholic HawaiianJet's Avatar
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    Quote Originally Posted by SmokinLowriderSS View Post
    Straub is working good advice and info for ya HJ. Good luck with the upgrades.
    Yeah, he's the best!

    Not in any hurry right now, I just got bored and started planning my winter upgrades, in the middle of summer.
    HJ

    ***FOR SALE*** 1978 19' Full Stringer Hawaiian Molokai Jet Boat w/ Berkeley 12JC-AB and Chevy 440 Tall Deck ***FOR SALE***

    Quote Originally Posted by mako shark mark View Post
    Oh yeah, Forgot to mention that the hull is a special mixture of speedcote, herculiner and rain-x, all blended together- good for another 8 mph top end.

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