Input please: possible gains from a cam swap?

Discussion in 'Engine Topic' started by Paul in MV, Feb 3, 2011.

  1. Paul in MV

    Paul in MV Member

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    All:

    Thanks for the replies.

    Definitely looks like I need to qet the quench dims right, confirm the cold air intake is not a constraint, and look at either a change to 1.6 rockers (easy) or a cam swap (less easy).

    Additional cam recommendations for the current setup are welcome, but I am not willing to move to a 383 right now.
     
  2. gregs78cam

    gregs78cam Member

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    OK. If not willing to go 383 yet, then put the money into a roller cam/lifters. Decide which way you want to go with the engine. Do you want to spin the thing past 6000rpm to get lots of horsepower, or do you want to make lots of torque below 6000rpm where you use it everyday. That will determine what duration to get. Those heads will flow pretty well up to about 6500rpm (I think - would have to do more research), but to make good use of a cam that large in duration you are going to need more compression. If you don't want to go 383 then there is no sense in tearing down the engine, unless you want to be absolutely sure about your quench. I don't know what is available in head gaskets nowadays, but if you can get your quench right with a gasket swap, then that should also bump the compression up slightly. Your best bet without getting into the bottom end would be to get a roller cam slightly larger than an RV cam, something good to around 5700rpm or so, and 0.500 - 0.525 lift, a roller cam will open and close quicker that is how you can get more lift in an RV cam than with flat tappets. That should give you more TQ and HP than you have now. My 383 has a custom Comp Cam Hyd.roller 224/230 @ .050, 0.525/0.524 lift with a small base circle and 4/7 swap. It made 340rwhp @5500rpm, 370Lb/ft TQ (pretty rich by the way) through the T-56. It was a LOT of fun to drive. And your heads flow slightly more than my TrickFlow 23* heads.

    That's the best advice I can give you. Good luck.
     
    Last edited: Feb 5, 2011
  3. sweetsoul

    sweetsoul Veteran Member

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    paul , read this article.it explains port sizes , valve sizes and intake velocity.may help you with your issues.
    article by joe mondello
     
  4. SKIP WHITE

    SKIP WHITE Member

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    The cam you have has a very small amount of lift, considering the heads you have, but the duration is more than good. You could get a cam with more lift, but no more duration in my opinion. Calculate what your quench is. You would want this around .040 and hopfully raise the comp. ratio a bit while doing this. Iron heads will limit how much you can go, but 350 size engine can go to about 10.4 give or take. I didn't see what weight of car you have, but if your car is 3300 or less, then the above recommendations stand. The heads you have hopefully have enough spring and valve length to increase your cam lift. I would go around .510 give or take. Many factors involved. You need address them all. You have good heads, and rather large, but that's ok. Your cam is terribly small in lift to make any decent power and sound. If your gearing is taller than 3.55, (numerically lower) than you may not want to do much to this car. Be sure and go with a decent stall, 28-32 range. You mentioned being concerned about piston to valve issues, your far from encountering any issues with this, if your pistons have two valve rel. Read all of this good info in this post, and I'm sure there are many more on the subject. Cams of a certain size in 383's will not have the same results in your 350 This is where the 350 falls short.
     
    Last edited: Feb 6, 2011

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