upgrade choices

Discussion in 'general muscle car related info' started by Grumpy, Jul 20, 2015.

  1. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member


    with a 4000 lb car and a basically stock 350 short block youll want all the torque you can get in the lower and mid rpm bands, torque is the result of efficiently using cylinder pressure, great flowing heads are mandatory for max potential power and better heads tend to partially compensate for a slightly milder than ideal cam, but the current cams a bit too large in duration and the heads are restrictive ,given the budget limitations and reluctance to totally rebuild it as a 383 stroker config, and Id bet the reluctance to go with a flat tappet solid lifter cam, Id suggest going this route.(parts listed below)
    the old chevy smogger 882 heads are very old and restrictive technology
    [​IMG]
    even the more modern and fairly reasonable priced rhs heads flow much better
    GM 882
    Valve Exhaust Exhaust Open
    Intake Lift w/ pipe
    0.050 39 34 34
    0.100 58,59,70

    0. 200 125 108 109
    0. 300 175 135 136
    0.400 204 141 143
    0.500 205 142 144
    0. 600 206 142 145
    E/I 69% 70%

    http://www.competitionproducts.com/Short-Blocks-Chev-SB/departments/1224/

    [​IMG]

    http://www.strokerengine.com/SBCHeadsFlow.html
    READ THESE LINKS
    http://www.superchevy.com/how-to/engines-drivetrain/sucp-0701-chevy-cylinder-heads/

    http://www.chevelles.com/forums/showthread.php?t=370311




    [​IMG]
    [​IMG]
    I doubt youll quite reach 400 hp but youll darn sure have a more streetable combo with noticeably better low and mid rpm torque over the rpm band your using 90% of the time.
    going with a roller cam and lifters would cost enough, of that $2K budget, to exclude the purchase of better heads and the heads are more critical to boosting operformance.

    heads (low cost but noticeably better than current 882 heads)
    http://www.summitracing.com/parts/sum-162109

    SPEND A BIT MORE and get better heads (personally I think $240 extra,very well spent)
    http://www.jegs.com/i/Brodix/158/1021004/10002/-1?parentProductId=760699#moreDetails
    or
    http://www.profilerperformance.com/racing/cylinderheads/sbc-23-degree

    milder crower cam
    http://www.summitracing.com/parts/cro-00240

    rhoads lifters
    http://www.summitracing.com/parts/rhl-8178/overview/

    1.6:1 erson rockers
    http://www.ebay.com/itm/like/291431719883?lpid=82&chn=ps

    RELATED INFO
    youll learn a good deal by reading through

    http://garage.grumpysperformance.co...-calculators-and-basic-math.10705/#post-46582

    http://garage.grumpysperformance.co...rocker-ratios-and-the-effects.126/#post-38478

    http://garage.grumpysperformance.com/index.php?threads/breaking-in-a-cam.798/#post-1160

    http://garage.grumpysperformance.co...lifter-to-increase-oil-flow.11152/#post-49968

    http://garage.grumpysperformance.com/index.php?threads/port-speeds-and-area.333/

    http://garage.grumpysperformance.com/index.php?threads/semi-fool-proof-cam-sellection.82/

    http://garage.grumpysperformance.co...lsa-effects-your-compression-torque-dcr.1070/

    http://garage.grumpysperformance.com/index.php?threads/sellecting-cylinder-heads.796/
     
    Last edited: Apr 2, 2017
  2. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    yes you can find cheaper rockers , but remember your rockers take a constant beating and decent QUALITY is mandatory, and getting the valve train clearances, push rod lengths, and geometry correct MATTERS
    these should work

    http://www.summitracing.com/parts/scc-scp1036/overview/
    [​IMG]

    but if it was my engine ID only consider these comp cams steel, roller rockers if limited to fairly low priced roller rockers from SUMMIT racing, steel has a noticeably longer fatigue stress life
    http://www.summitracing.com/parts/cca-1602-16/overview/
    [​IMG]

    [​IMG]
    Valve Spring Retainer to Rocker Arm Clearance
    When installing the rocker arms, check to see that the inside of the rocker arms clear the spring retainers. Many rocker arms have a "relief" to accommodate large valve spring retainers.
    [​IMG]
    yes youll want too use push rod guide plates on most heads when your not using self centering rockers
    [​IMG]

    while your rocker wear marks on the valve tips look very close to ideal , you need to verify the push rod length, as getting that rocker geometry correct is important to durability , and a slight change in push rod length may improve that further, keep in mind that having the wear band centered is nice but not as important as keeping in narrow and close to center as possible as a narrow wear band tends to indicate minimal side thrust and as a result minimal wear results
    [​IMG]

    "THAT PLASTIC THING" is a PUSH ROD LENGTH CHECKER, THE PUSH ROD LENGTH CHECKING, AND ROCKER GEOMETRY TOOL, ARE ENGINE SPECIFIC, so you MUST USE ONE DESIGNED FOR THE SAME STUD DIAM. SPECIFICALLY FOR YOUR particular ENGINE, and cylinder head design, to find the correct rocker geometry and push rod length. If you for example use one designed for 7/16" studs on a SBC and used it on a BBC with 7/16" rocker studs the result would not be close to correct, if the tool designed for one engine is used on the wrong engine, so be damn sure you use the correct tool.
    if your seeing a .120-.150 gap between the push rod tip when the "PLASTIC THING" is inserted on the rocker stud ,with the cam lobe /lifter on the base circle AND IF ITS THE CORRECT CHECK TOOL FOR THE APPLICATION,and its resting on the valve tip, your push rods that much too short for the application, your measuring, if the tool rests on the push rod tip and its lets say .060 off the valve tip, that indicated the push rods that much too long for THAT particular application, get within .040 or less on either meassurment and your fine


    viewtopic.php?f=52&t=4596&p=18401&hilit=adjustable+guide+plates#p18401

    viewtopic.php?f=44&t=2839&p=7344&hilit=adjustable+guide#p7344
    yeah I know many guys would rather slash their wrists,
    then read through a couple hours worth of links and sub links.....
    try to avoid only reading links ,
    only to find out WHY expensive parts need to be replaced AFTER they broke

    but for the guys that want a durable engine ....heres help


    http://garage.grumpysperformance.co...ch-is-best-steel-or-aluminum.3124/#post-51904

    http://garage.grumpysperformance.co...-rockers-and-the-pushrods-rub.198/#post-46882

    http://garage.grumpysperformance.co...rocker-ratios-and-the-effects.126/#post-37600

    http://garage.grumpysperformance.co...-rockers-and-the-pushrods-rub.198/#post-46856

    http://garage.grumpysperformance.com/index.php?threads/valve-train-clearances-and-problems.528/

    http://garage.grumpysperformance.co...swap-in-1-6-1-ratio-rockers.10671/#post-46039

    http://forum.grumpysperformance.com...&p=18401&hilit=adjustable+guide+plates#p18401

    http://garage.grumpysperformance.co...-calculators-and-basic-math.10705/#post-46582

    http://garage.grumpysperformance.co...s-on-valve-spring-pressures.10268/#post-43515

    http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/

    spending a few days or even weeks doing careful research well before you start writing checks or pulling out a credit card, can save you thousands of dollars and months of work, understanding the difference in component quality ,correct clearances and how and why each component is supposed to perform and the potential stress its under helps you make far more intellegent choices and tends to allow you to get an engine built that far exceeds the quality and performance of the average crate engine assembly


    http://garage.grumpysperformance.com/index.php?threads/adjusting-valves.196/

    http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/

    http://garage.grumpysperformance.co...u-buy-bare-or-assembled-heads.534/#post-41293

    http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/

    http://garage.grumpysperformance.com/index.php?threads/valve-train-clearances-and-problems.528/

    http://garage.grumpysperformance.com/index.php?threads/sellecting-cylinder-heads.796/

    http://garage.grumpysperformance.com/index.php?threads/valve-seat-angles-and-air-flow.8460/
     
    Last edited: Sep 11, 2015
  3. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    "




    I'd tend to disagree, about the exclusion of the 1.6:1 rockers vs the 1.5:1 ratio rockers use, in this particular application, simply because with such a mild cam running at less than 6000RPM the vast majority of the time. the increased lift and minor increase in stress with that low lift, mild valve spring load rate is negligible compared to the minor but still useful gains in valve lift and air flow, vs the 1.5:1 rockers
    http://www.wallaceracing.com/rockercalc.php

    http://www.pontiacstreetperformance.com/psp/RockerArms.html
    [​IMG]
    graphing out the change in lift at the valve with a
    1.5:1 vs 1.6:1 ratio rocker valve lift diagram would look similar too this
    Rocker Arm Ratio Explained
    You've heard of 1.5:1 ratio and 1.6:1 ratio rocker arms. What does that really mean? How can you make more horsepower by using the larger ratio rocker arms?

    The ratio of a rocker arm refers to the amount of movement on the valve side of the rocker arm in comparison to the pushrod side. A 1.5:1 rocker arm will move a valve 1.5 times the lift of the cam, assuming all things are in proper working order. If your cam has a lift of .4 inches, multiply by 1.5 to get .6 inches of actual valve movement. With the same cam lift of .4 inches: If you do the math on a set of 1.6:1 rocker arms: Multiply 1.6 x .4 inches of cam lift. You get .64 inches of actual valve movement. Essentially, changing to a larger ratio rocker arm is the same as increasing the lift of your cam the same amount. Opening both valves further usually is a benefit in the power department as your engine is capable of moving more air and exhaust through it.

    http://www.promaxxperformance.com/index.php/racing-parts/sbc/sbc-small-block-chevy-1860.html

    lets look at the cam & heads
    http://www.summitracing.com/parts/cca-cl12-238-2

    http://www.summitracing.com/parts/pmx-2168/overview/make/chevrolet
    [​IMG]

    at .469 max lift with a 1.5:1 ratio rocker, and a 90% port throat cross sectional area, your looking at a 1.219 square inch valve curtain

    at .500 max lift with a 1.6:1 ratio rocker, and a 90% port throat cross sectional area, your looking at a 1.416 square inch valve curtain,
    a roughly 16% gain in peak flow for roughly a 5-6% increase in applied peak valve spring pressure.

    but whats the valve spring load rate PRESSURE?

    looking at the info I can find , theres about 110lb seat and 310lb peak at .575 max lift, the valve spring load rate increases about 11 lbs from about 244 lbs at .469 lift to about 255 lbs at .500 lift or about .05%

    calculate the engine increased power potential or power increase from the air flow change, shows its use of the higher ratio rockers should allow about a 15-20 hp advantage
    http://www.wallaceracing.com/calcafhp.php

    http://users.erols.com/srweiss/calcafhp.htm

     
    Last edited: Jul 23, 2015
    Strictly Attitude likes this.

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