454 BBC cam question
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454 BBC cam question

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    Senior Member holorinhal's Avatar
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    Default 454 BBC cam question

    I have a stock Hardin marine 454, 4bolt with peanut port heads, holy street dominator intake and a 750 demon carb.
    I am going to do a head swap to 049 heads with the stock 2.06/1.72 valves, Edlebrock RPM air gap and an 850 DP.
    I have no idea as of yet what the specs on the existing cam is, but I am assuming whatever the cam that came in those engines originally.
    I have a comp cams Hydraulic flat tappet camshaft, 11-207-3 - Magnum™ Hydraulic Flat Tappet Camshafts sitting on the shelf and while I had things appart, was thinking of trying it out in this engine.
    My question is, how well do you think this cam would work in this engine? would it be an improvement over whatever is in there, or would it be a dog? would it be too much or too little? Any information would be appreciated........H

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    Some guy obnoxious001's Avatar
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    Quote Originally Posted by holorinhal View Post
    I have a stock Hardin marine 454, 4bolt with peanut port heads, holy street dominator intake and a 750 demon carb.
    I am going to do a head swap to 049 heads with the stock 2.06/1.72 valves, Edlebrock RPM air gap and an 850 DP.
    I have no idea as of yet what the specs on the existing cam is, but I am assuming whatever the cam that came in those engines originally.
    I have a comp cams Hydraulic flat tappet camshaft, 11-207-3 - Magnum™ Hydraulic Flat Tappet Camshafts sitting on the shelf and while I had things appart, was thinking of trying it out in this engine.
    My question is, how well do you think this cam would work in this engine? would it be an improvement over whatever is in there, or would it be a dog? would it be too much or too little? Any information would be appreciated........H
    Jet boat,, which impeller and what rpm do you think you want to run(and will you get the impeller cut or leave as it is?). I am thinking [email protected]" is kind of small for a jet, but I guess you are planning on leaving the small valves in the 049's?

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    Or Seth, either one Budweiser's Avatar
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    Hey Hal,

    I had a very similar cam in a very similar engine in a v-drive. I liked it a lot. Idled well with a slight lope and ran great. Pulled strong up to about 5200 in my particular application. Pretty sure the one I had was a split duration, 224/234, or something like that though.

    I remember taking into account when I chose the cam, that research lead me to believe stock 049's flow well up to about 0.500", with little gain above that.

    I think it's worth stabbing it in there if someone can verify that there's not too much overlap for wet exhaust. Personally, I'd install the suggested springs in the head or have the existing springs checked if you don't know what they are.

    I'd also consider saving the money and sticking with the 750 carb.

    I'd assume it would put the combo in the neighborhood of 400-450hp in the 5500 rpm area.

    What pump/impeller do you have?

    Edited to add... Looks like a C cut impeller would match well.
    Last edited by Budweiser; 03-16-2016 at 09:38 AM.

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    OEM GM heads like a 10 to 14 degree split favoring exhaust. Single pattern in OEM headed engine with un ported heads is not optimal. To use a single pattern one would have to modify the exhaust flow only and leave the intake alone.
    Chris Straub
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    Senior Member holorinhal's Avatar
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    Quote Originally Posted by obnoxious001 View Post
    Jet boat,, which impeller and what rpm do you think you want to run(and will you get the impeller cut or leave as it is?). I am thinking [email protected]" is kind of small for a jet, but I guess you are planning on leaving the small valves in the 049's?
    Barry, yes it is a Berk jet with an AB impellor. I have the heads already and are fairly fresh, with upgraded(not OEM) springs. I do not intend to put bigger valves in, at this time. Running dry headers.
    These are just parts that I have already, that will not cost any out of pocket money and was wondering if there would be any gain in performance over the peanuts and stock existing cam. I have a 750 Demon on the engine already and if it is suited better, I will run that instead of the 850.
    I am not expecting a huge gain in performance, over what is already there, just some sort of improvement, if at all, so there fore I cant say what rpms, I would want to get out of it, just not worse off than it is already, and its not horrible now, for what it is.
    At present I am turning around 4500 at wot. If there would not be any gain at all or possibility of running worse, then I will leave things well enough alone.
    I am already in the process of collecting parts, to put together another engine to replace my 489 and only need pistons rods and bearings, to get started.
    Last edited by holorinhal; 03-16-2016 at 05:46 PM.

    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

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    Senior Member holorinhal's Avatar
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    can you guys help me understand what the single pattern/dual pattern cam principle is? is single / dual pattern the same as split duration?
    I seem to struggle with looking at cam specs and understanding how one is better than another.

    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

    73 KONA Restoration http://www.performanceboats.com//showthread.php?t=10678
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    Quote Originally Posted by holorinhal View Post
    can you guys help me understand what the single pattern/dual pattern cam principle is? is single / dual pattern the same as split duration?
    I seem to struggle with looking at cam specs and understanding how one is better than another.
    yes split duration vs equal duration helps the exhaust flow equal to the intake. For what its worth I have never ran anything other than a split duration cam on a BBC especially with the head combo you have. NOT THAT IT"S BAD. I am and have " many times" ran same style configurations with great results. Put together and put your'e ass in the seat and see how it works. Just do one thing and spring the heads for the RPM you wish to achieve. MLAO mark

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    Senior Member holorinhal's Avatar
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    Quote Originally Posted by ol guy View Post
    yes split duration vs equal duration helps the exhaust flow equal to the intake. For what its worth I have never ran anything other than a split duration cam on a BBC especially with the head combo you have. NOT THAT IT"S BAD. I am and have " many times" ran same style configurations with great results. Put together and put your'e ass in the seat and see how it works. Just do one thing and spring the heads for the RPM you wish to achieve. MLAO mark
    Ah Ha, now I see. So It is better to have a duration a few degrees larger on the exhaust side? Is this specific to a BBC and a jet boat or does it apply across the board in any engine and regardless of street or marine?

    Ok so if I decide to try the cam, then I should get the springs that comp suggests to go along with it? They are suggesting 911-16 or 924-16 dual spring. They say that the dual springs require machining on the head. so would the 911- 16, work?

    The springs that are installed on the head were matched to a clay smith cams with 231/231 duration and a .560 valve lift, in a jet with a ab impy.

    I really don't know what rpm to expect to run, but I would like to shoot for more than the 4500, I am getting out of it now. The rpm range of the cam is 5800. Should I aim for that, even though I know that I would not reach it with the impellor that I have?

    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

    73 KONA Restoration http://www.performanceboats.com//showthread.php?t=10678
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    Senior Member ol guy's Avatar
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    Quote Originally Posted by holorinhal View Post
    Ah Ha, now I see. So It is better to have a duration a few degrees larger on the exhaust side? Is this specific to a BBC and a jet boat or does it apply across the board in any engine and regardless of street or marine?

    Ok so if I decide to try the cam, then I should get the springs that comp suggests to go along with it? They are suggesting 911-16 or 924-16 dual spring. They say that the dual springs require machining on the head. so would the 911- 16, work?

    The springs that are installed on the head were matched to a clay smith cams with 231/231 duration and a .560 valve lift, in a jet with a ab impy.

    I really don't know what rpm to expect to run, but I would like to shoot for more than the 4500, I am getting out of it now. The rpm range of the cam is 5800. Should I aim for that, even though I know that I would not reach it with the impellor that I have?
    before replacing the springs you have first off how old are they and before having the spring seats opened up for a dual spring set-up. have the spring pressure checked at seat and at cam max lift.Might save a buck or two.

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    Senior Member holorinhal's Avatar
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    The existing springs have only one or two seasons on them.
    I was referring to using the suggested comp #911-16 single spring, to keep from having the seats machined.
    Last edited by holorinhal; 03-17-2016 at 09:16 PM.

    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

    73 KONA Restoration http://www.performanceboats.com//showthread.php?t=10678
    '81 Spectra 20 Facelift http://www.performanceboats.com/user...-facelift.html

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    Or Seth, either one Budweiser's Avatar
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    Quote Originally Posted by holorinhal View Post
    The existing springs have only one or two seasons on them.
    I was referring to using the suggested comp 912-16 single spring, to keep from having the seats machined.
    If the springs that are already on your heads have comparable specs I'd just leave them on and run 'em. Otherwise, yes the 912-16 is what I'd go with.

    Unless the 049's lower your compression (don't know off hand the chamber sizes of the two heads), you'll definitely see more RPM's with the cam and head swap. I'd consider looking into an impeller adjustment/replacement after you get an idea where it ends up in it's new configuration. Get your max RPM around 5500 and call it good.

    If you have the 850 carb already, go ahead and run it if you like. It wont hurt anything, but gains will be marginal to nonexistent. Otherwise, the 750 will be just fine.

    Your current existing combo is right about 275 horsepower. Shouldn't be too hard to improve your situation. There's an easy 100+ HP gain well within your reach

    Where do you use the boat most?
    Last edited by Budweiser; 03-17-2016 at 09:33 AM.

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    Senior Member holorinhal's Avatar
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    Yea, Budweiser, I do already have the 850, but also have the 750 that I have been running, so if the 850 would be overkill, I will may just stick with the 750.

    Well I will pull the timing cover, this weekend and see if there are any numbers at all, on the nose of the existing cam, to try and figure out what I have already.
    I changed the timing set, when I first bought the engine, out of another jet boat, to replace the oem aluminum/nylon gear, but I don't recall seeing any thing scribed on the cam, which leads me to believe it is an oem camshaft.

    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

    73 KONA Restoration http://www.performanceboats.com//showthread.php?t=10678
    '81 Spectra 20 Facelift http://www.performanceboats.com/user...-facelift.html

    18' Advantage http://www.performanceboats.com/jet-...k-project.html

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    Run the 049 heads. When approaching .550 lift, be sure to check the retainer to guide clearance. Sell the 750. 049`s will flow. I have a milled .030 set with 2.190/1.880 valves on a 489 that runs 10.200 et @ 6300 rpm`s. Runs 9.70 @ 6700 with a 150 shot. 1150 Dominator. Same heads, cam and boat with a 468 assembly & 850 dp ran 11.00`s @ 5800. Texas Tunnel hull. B impeller.

  16. #14
    Or Seth, either one Budweiser's Avatar
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    Quote Originally Posted by holorinhal View Post
    Yea, Budweiser, I do already have the 850, but also have the 750 that I have been running, so if the 850 would be overkill, I will may just stick with the 750.

    Well I will pull the timing cover, this weekend and see if there are any numbers at all, on the nose of the existing cam, to try and figure out what I have already.
    I changed the timing set, when I first bought the engine, out of another jet boat, to replace the oem aluminum/nylon gear, but I don't recall seeing any thing scribed on the cam, which leads me to believe it is an oem camshaft.
    It won't be overkill in the sense that it will be a detriment to performance. But, any gains will likely not be worth paying the price of even a used 850. Especially if you don't change your impeller and let the engine run up into it's peak HP range. If ya got it, try it, or just run it. It won't hurt performance either way.

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