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Technical Cam lift

Discussion in 'The Hokey Ass Message Board' started by Edward E Scheib, Jul 1, 2020.

  1. Edward E Scheib
    Joined: Feb 28, 2020
    Posts: 18

    Edward E Scheib

    I've been told the max. lift on a cam for my stock 1957 283 with power pack heads is somewhere near .580. Is this correct. Also am i dealing with flat top piston on a stock 283. Thanks.
     
  2. Jmountainjr
    Joined: Dec 29, 2006
    Posts: 1,114

    Jmountainjr
    ALLIANCE MEMBER

    I guess if you do enough machine work you might get there. You won't with stock parts. That is way more lift than a 283 wants or needs. Your stock compression ratio won't support that much lift. It takes a pretty healthy, and not stock, 283 or 301 to run a cam in the 0.480" range.
     
  3. Roothawg
    Joined: Mar 14, 2001
    Posts: 19,751

    Roothawg
    Member

  4. Mike VV
    Joined: Sep 28, 2010
    Posts: 1,934

    Mike VV
    Member
    from SoCal

    Ed -

    Please explain your question with MORE detail.
    What's the purpose of wanting so much lift, on an otherwise "apparently..." a stock engine ?

    Stock heads and .580"+ valve lift is all but useless..!

    Mike
     
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  5. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,225

    56sedandelivery
    ALLIANCE MEMBER

    Do your pistons have valve reliefs??? The earliest 265's/283's pistons, did not have valve reliefs, and GM did a TON of warranty work due to valve clearance issues, and this was with stock cams having .336 intake/.343 exhaust in 1955 passenger cars, or .4043 intake/.4136 exhaust in the Corvette's. 1956 passenger cars, .373 intake/.373 exhaust. 1957 passenger cars, .398 intake/.398 exhaust. So, some fairly low lift cams in the early Chevrolet V-8's that had pistons without valve reliefs; and warranty work due to clearance issues. With valve reliefs, the lift can be greater, but .580 is too much, IMO. Valve springs would also have to be such to prevent valve float at higher RPM's as that could also cause clearance issues. I took these camshaft specs from my 1959 edition of "MOTOR'S".
    I am Butch/56sedandelivery.
     
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  6. Edward E Scheib
    Joined: Feb 28, 2020
    Posts: 18

    Edward E Scheib

    Wanting to get some sound out of my motor. Some lope. Already have headers, installing low rise dual quad with 500cfm carbs. Not worried about breaking any track records. Stock power glide. Dont care about high lift numbers. Just some one from Isky Cams said i could go as high as 580. I've been looking at Comp Cam Thumper. Thank you for your input
     
  7. Edward E Scheib
    Joined: Feb 28, 2020
    Posts: 18

    Edward E Scheib

    Im thinking about Comp Cam Thumper. Any ideas?
     
  8. Mike VV
    Joined: Sep 28, 2010
    Posts: 1,934

    Mike VV
    Member
    from SoCal

    More "duration" and or "overlap" is where the lumpy sound comes from, NOT...the lift.
    I'd be looking at a few degrees of overlap, like maybe a 106° or a 108° valve centerline cam.

    Again, with stock, Power Pack heads, about .450" lift will be a lot for that intake port. Anything more is waisted motion by the cam, rockers and the valves.

    Mike
     
  9. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,175

    gimpyshotrods
    ALLIANCE MEMBER

    TWO 500s on a 283?!

    You don't even need ONE on a 283.
     
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  10. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,225

    56sedandelivery
    ALLIANCE MEMBER

    The stock stall speed on that 57, cast iron Powerglide is pretty low, and reaching a compromise between the stall speed and the camshafts characteristics, will be the challenge. It's always something; one modification leads to another, and another, and another................................................I am Butch/56sedandelivery.
     
  11. That's more of a sound effects cam, probably what you want. But don't get the biggest, more like the smallest in the range.
     
  12. Roothawg
    Joined: Mar 14, 2001
    Posts: 19,751

    Roothawg
    Member

    I am afraid you will have a sound, but it will sound like a drowning 283.
     
  13. Jmountainjr
    Joined: Dec 29, 2006
    Posts: 1,114

    Jmountainjr
    ALLIANCE MEMBER

    I think your first step should be to verify just how much cam lift your current components will take before buying a cam. Some cams will require valve spring changes. You can gain, or lose, clearance depending on the valve spring retainer used. There are a few cams that will give you somewhat of a lopey idle and better performance than using a Thumper or VooDoo type cam. If you are set on that type of cam, follow the break in directions carefully as the lobe ramps as a bit aggressive. As for two fours on a 283, make sure they are small and have air flow controlled secondaries.
     
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  14. 1971BB427
    Joined: Mar 6, 2010
    Posts: 5,687

    1971BB427
    Member
    from Oregon

    I've used the Thumpr cams and they do have a deep, lopey idle. But they also have enough overlap, and extremely short LSA that the exhaust smell will burn your eyes! I'd suggest you take a look at Howards Cams Rattler series, which will also have a nice lope, but have better cams specs, and wider LSA so they make more power, and burn cleaner.
    Stick with one of their Rattler cams that's under .500" lift for your 283, as a stock 283 wont perform well with too much lift, unless you make other upgrades also. And too much lift will end up pulling out rocker studs if your heads don't have screw in studs.
    This one would be a good choice for the stock 283 SBC.

    https://www.howardscams.com/hydraul...hevy-262-400-1800-5600-howards-cams-118001-09
     
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  15. F-ONE
    Joined: Mar 27, 2008
    Posts: 2,131

    F-ONE
    Member
    from Alabama

    Edward,

    I could have a sarcastic response but I’m not going to do that. It’s no help to you.

    This board is full of real world practical knowledge and if you ask the right question, provide the right information and have the right attitude in your responses. You will learn a lot and maybe even save a lot of money.

    Right now I think you are throwing a lot of cash at this 283 to see what will stick.

    I suggest you start a new thread since there’s about a kazillion cam threads on here.

    “Help me hop up my 283 in my.....”
    Tell about your car.
    What kind of car.
    What gear ratio.
    What tire size.
    What your goal is.
    Ask what really works or worked best for you.
     
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  16. throw an L79 cam in it. With the small bore motor it will sound plenty healthy.
     
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  17. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,175

    gimpyshotrods
    ALLIANCE MEMBER

    Drowning, for sure.

    For perspective, I have two 500s on my 354.

    Still, that is way more than a 354 would need, too, until you consider that between them, and the aforementioned 354, I have a 6-71 blower.

    The only way I can see this working out for him is disabling the secondaries.
     
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  18. Ericnova72
    Joined: May 1, 2007
    Posts: 382

    Ericnova72
    Member

    The 500 Edelbrocks are vacuum air door secondary, they will only flow as much as the engine will pull through them....they cannot "drown the motor". His 283 is never going to use all they COULD offer, but it isn't going to "drown the motor".
    Yeeesh.

    Cam choice??
    Crane #10017, also known as the 274H06. Advertised duration 274°/274°, 218°/218° dur @.050", .450°/.450" valve lift, 106° lobe separation.
    Same grind is available from the Summit house brand cams, # SUM-1785
    Mild enough in duration for the stock torque converter, but tight lobe separation to give an aggressive lope...one of the more popular aftermarket grinds ever. Just a bit less duration than the 350HP 327 cam but a lot tighter lobe separation for better low end and mid-range torque and more lope.
    https://www.summitracing.com/parts/sum-1785/make/chevrolet
    https://www.summitracing.com/parts/sum-k00172/make/chevrolet
    https://www.summitracing.com/parts/crn-10017

    I'd change to the "Z28" valvespring at the same time to go with any aftermarket cam.
     
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  19. Roothawg
    Joined: Mar 14, 2001
    Posts: 19,751

    Roothawg
    Member

    500 cfms are about all you need for a 283, vacuum secondaries or not.
    265's/283's don't like a lot of duration with no other mods.
    I would lean towards a 3x2. Just my opinion.

    I like the Comp Cams 260H for a stock 283.
    https://www.jegs.com/i/COMP-Cams/249/12-206-2/10002/-1
     
    Last edited: Jul 3, 2020
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  20. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,175

    gimpyshotrods
    ALLIANCE MEMBER

    Yeah, no.

    The secondaries are vacuum operated. The primaries are not. Even if the secondaries never open, the primaries will open, in a 1:1 synchronization.

    An Edelbrock 500 has 1.4375" primaries, and 1.6875" secondaries. The split between primary and secondary is 23:27.

    In other words, 46% of the rated flow comes from the primaries, or 230cfm.

    Operated as primaries only, at with a 1:1 linkage, that is 460cfm, available to an engine that only very optimistically requires 360cfm, at maximum RPM, with no regulation other than the throttle pedal.

    Perhaps you are unclear how the venturi-effect works, and that proper fuel metering is a function of velocity an pressure differential. Having a venturi that is too large, or having too many of them, or, in this case, having too many of them that are too large, will result in extremely poor fuel metering, due to low velocity airflow through the venturi.

    This is a recipe for terrible throttle response, poor performance, and horrible mileage.

    Do you know what happens when you move air too slowly through a venturi? You don't get proper fuel atomization. You get droplets!

    And droplets, well, drown an engine with fuel.

    Thank you for coming to my TED Talk.
     
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  21. Ericnova72
    Joined: May 1, 2007
    Posts: 382

    Ericnova72
    Member

    Nobody said it had to be run at 1:1 linkage, run it progressive, rear carb as the main.

    I knw about venturi effect...it isn't just venturi diameter that delineates response and fuel metering quality, the booster design has a big say in this too. The Edelbrock boosters are pretty decent, nearly as efficient as the Q-jet.

    Th factory put 2 420-ish cfm WCFB's on the 9.5:1 compression hydraulic cam dual 4 barrel 283 in 1960-61 and put 3.36 gears behind it and it wasn't known for drivability problems.....twin 500's isn't all that different.

    Poor guy comes on a "traditional rods and customs" site wanting advice on a cam with a nice lope and gets barbecue'd for running dual 4's on a 283, ya'll act like it can't be done, never works, flies in the face of god for even suggesting it....when the factory did very similar for 5 years before big single 4 barrels ever hit the scene.
    Life must be pretty boring when vanilla is the only flavor.
     
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  22. railcarmover
    Joined: Apr 30, 2017
    Posts: 401

    railcarmover

    its up to you how long your build lasts,over fueling an engine hits you right in the hour meter.Engine flows at 300 cfm? carb flow at 300 cfm,its not rocket science,building an efficient air pump..
     
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  23. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,175

    gimpyshotrods
    ALLIANCE MEMBER

    Good luck getting a low-rise dual quad manifold to give balanced air/fuel delivery with a progressive linkage.

    The WCFBs used on the dual-quad on a 283 were 375-390cfm, not 420cfm.

    I have access to the GM records from that era, and it quotes both numbers, as well as all of the service bulletins Carter sent to GM, calling for various strategies to get them to stop loading up at idle at low speed, and idle.

    Bottom line, even GM knew that they were just too big for the 283. The max quoted CFM, times two, is 780cfm (minimum 750), and GM knew that was too big.

    What was wrong? Carter and GM both identified the problem being the venturi velocity being too low!

    OMG! It is almost like I know what I am talking about!

    Now you are telling me that 1000cfm will be fine. It won't.

    Don't forget, you are talking to an actual Automotive Engineer, at General Motors here. I am not guessing. This is my actual vocation.

    If you need a third party to verify this for you, ask @carbking. He knows Carters inside and out, and probably can verify this, verbatim.
     
  24. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,366

    2OLD2FAST
    Member
    from illinois

    There's a lot of jokes about actual fucking know it all engineers , most aren't complimentary !Ever wonder why ? I'm reasonably sure it was engineers who said you would never get 1 HP per cubic inch ,& the list goes on........
     
  25. carbking
    Joined: Dec 20, 2008
    Posts: 2,805

    carbking
    Member

    If one is playing with an older pickup, and removes the hood; one can hire a 15-year-old to stand on the running board, and pour gasoline into the engine from a leaky boot! The engine may run. How well it may run will depend on the skill of the 15-year-old, and the size of the boot!

    Will a 283 run with two 500 CFM carbs? Probably. How well it will run, especially at idle, is an entirely different story.

    Carter performed mass-butchery on the two 375 CFM WCFB's used on the 283 to TRY to make them idle, even with progressive linkage. And I am old enough to remember those "mosquito foggers" when they were new. Pull up behind one at a light, and hope the light changes; because roughly every 15 seconds the engine would load up, and the driver would have to blow it out. You literally could not see the car for the black smoke!

    Some may (or may not) enjoy this link:

    http://www.thecarburetorshop.com/Multiplecarburetion.htm

    Gimpy is trying to give some sound advice, for a vehicle that is fun to drive at ALL RPM's.

    Someone much wiser than I once said something to the effect "those who ignore history are doomed to repeat it". And if I didn't get the exact quote, my apologies, but the content is close.

    Jon
     
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  26. birdman1
    Joined: Dec 6, 2012
    Posts: 914

    birdman1

    The 365 horse 327 cam sounds great. No need for aftermarket cams.
     
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  27. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,366

    2OLD2FAST
    Member
    from illinois

    Its not the advice , its the delivery .....
     
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  28. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,175

    gimpyshotrods
    ALLIANCE MEMBER

    There is no methodology one can employ to increase the temperature, even under the tightest of environmental controls, which will prevent the crystalline structure of Dihydrogen Monoxide from decomposition.
     
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  29. carbking
    Joined: Dec 20, 2008
    Posts: 2,805

    carbking
    Member

    Gimpy - what happens in 2021?

    Jon.
     
  30. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,175

    gimpyshotrods
    ALLIANCE MEMBER

    I am unsure that Humanity will continue as we know it long enough to find out.

    When's the last 3-month period you saw 18 people you know die?
     

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