is a roller cam worth the extra cost vs a flat tappet design

Discussion in 'Cams, Heads and Valve Trains' started by grumpyvette, Oct 30, 2010.

  1. grumpyvette

    grumpyvette Administrator Staff Member

    heres some info from COMP CAMS
    " Flat Tappet vs. Roller Tappet Lifters
    theres far more than just the cam and lifters required to swap types of cams, if your engines currently equipped with a flat tappet cam your almost sure to need a new
    timing chain set
    cam button
    new push rods
    obviously a new cam and roller lifters.
    and its almost always in your best interest to add better valves springs, retainers,keeper rockers etc.
    its also very common to need spring pockets cut, new spring shims etc.

    a flat tappet hydraulic cam will function correctly if properly installed but compared to a decent roller cam it can easily cost you 30-40 plus hp in some applications
    good hydraulic flat tappet cams and lifters are significantly less expensive at $170-$600 for name brand components vs $870-$1500 for a roller set up,obviously depending on components selected and changes required.
    generally its best to purchase all the listed components in a cam installation kit (cam, lifters,valve springs, etc. ) from a single manufacturer as mixing parts, sources or brands,
    allows the cam manufacturer to void the warranty, even if the parts in the kit they sell are either identical or inferior to,
    the individually purchased components you individually sourced. keep in mind most manufacturers will have tested parts compatibility ,
    so they are reasonably sure the components they sell in the kit will work, that can,t be always assumed,
    with randomly matched parts even if those parts are good quality.

    Isky claims that the Comp XE cams violate the 47.5% rule. The 47.5% rule applies to flat tappet cams for SBCs with 1.5 rockers but the concept is still the same for other configurations where the designs are "on the edge" or "over the edge" for lobe intensity. For 1.5 ratio SBCs, the duration at .050 must exceed 47.5% of the total valve lift or your asking valve train problems. For example, take a Comp Cams Magnum 280H, with 230 duration and, 480 lift...230/.480 = 47.9% which exceeds 47.5% therefore would not pose a threat to components. We do not regularly hear about the older, safer HE and Magnum designs rounding off lobes anywhere near as often as the XE cam designs. Unfortunately, some of the Comp Cams XE dual pattern lobes break this 47.5% rule on the intake side so they are likely to be problematic. The design has "steeper" ramps that are too quick for durability and reliability according to other cam manufacturers. They will wipe lobes in a heart beat especially if you have not followed the proper break-in procedure. Other designs are more forgiving during break-in and less likely to fail.

    In nearly all circumstances, a good roller camshaft design will outperform its flat tappet counterpart. Among the benefits of roller cams are higher tappet velocity, more lift and more area, along with reduced valve train friction (often a 15+ hp increase) and higher engine rpm with little effect on low speed driveability and power.

    Roller tappets are also reusable, which makes it possible to swap just the camshaft without the expense of new lifters. And finally, roller tappets are far less prone to wear, allowing higher spring loads, and they are more consistent with today’s oils.

    The biggest advantage to building an engine with a flat tappet cam and lifters is the lower up-front cost. It can be significantly less expensive to use a flat tappet setup but should you decide to install a new camshaft, flat tappets are not reusable, roller lifters are more expensive. You will need new lifters as well.[/color]"

    the answer depends on your goals, a good flat tappet cam and lifters usually costs $400-to under $240 some times under $159,
    keep in mind the main reason solid lifter roller cams tend to have reputation for durability issues is the much higher valve spring pressures and stress levels used to allow solid roller cams to operate at high rpms, once you exceed about 6000 rpm valve train stress loads increase rapidly

    keep in mind this is a small base circle cam with asymmetrical cam lobes you must use the .050 lift and duration numbers in calcs


    example ... rs/tie-bar

    Read this link

    for name brand parts, off brands can be even cheaper

    [​IMG] ... z2FeQk91VU



    most flat tappet cams use 110 lb-130 lb seat pressure springs ,
    you can get by with the 140 lb-150 lb seat pressure springs in almost every application,
    with a roller lifter cam, IF ITS A HEAT TREATED SURFACE HARDENED cam
    but I would have suggested swapping to a billet cam by the time the seat pressure was much over 150 lbs
    as the pressure on the lifter roller wheel increases so does the potential for having issues if you match a roller lifter and a soft cam lobe.

    its NOT TYPICAL on the cheaper cams but its NOT hardly what you might call rare on cams that try to basically maximize results, and the current roller cam designs, because if you think about it the lobe is forced open as the roller rolls up and over the cam lobe but only spring pressure returns the valve most of the way to the cylinder head seat and they don,t want it to slam down and bounce so the lobe designs can be ground differently.An Asymmetrical cam has opening and closing ramps that are unlike and unequal. This profiles usually found on high performance cams and offers a high velocity opening and a lower velocity closing ramp in order to snap the valve open quickly and then set it back down more gently.
    roller cam lobe designs are more complex than flat tapper cam lobes simply because the roller lifter allows much more precise valve open and timing events,
    lobes on a roller cam,are generally asymmetrical, in the better roller cam lobe designs,
    as its more important to open the valve fast, to maximize cylinder fill rates,
    but reduce the valve seating/sealing, timing velocity, too prevent the valve bouncing off the seat as or after its closed,
    this factor helps stabilize cylinder scavenging and valve train durability,
    and stability but should not effect the software dyno results



    factory blocks with sheet steel lifter retention springs are NOT designed to exceed about .550 lift or 6000rpm
    STOCK dog bone design hydraulic enclosed wheel roller lifters are generally designed for less than .550 lift and less than 6000rpm
    the stock Chevy hydraulic roller lifters , dog bone and spider springs don,t always work reliably, ALL THE TIME with engines having over .500 lift or when spun over 6000rpm, its not all that rare for the lifter ,retainer to bend the retainer spring allowing the lifter to spin sideways, in the lifter bore, resulting in a destroyed cam, thats why Ive suggested BRAND NAME ,AFTERMARKET RETRO FIT CAM COMPONENTS BE USED

    roller blocks have taller lifter bores, because roller lifters are taller, and a provision to bolt the lifter retainer spring, but they can be very easily used for the earlier flat tappet lifters if desired by simply removing the spider(SPRING RETAINER), keep in mind most roller blocks use one piece rear seals.
    KEEP IN MIND that a good deal of the power in any engine combo will be the result of how efficiently you blend factors like,
    EFFECTIVE COMPRESSION,vs fuel octane
    CYLINDER HEAD FLOW rates vs displacement
    EXHAUST scavenging efficiency.(cam timing)
    theres a good deal of math involved, that can be used to accurately predict the results but there's also an ART and SKILL to tuning and engine assembly, and experience goes a long way there.
    and yes a slight mis-match of components, not getting the clearances correct, or a few degrees of cam duration,plus or minus from what the engine needs, and a few cfm difference in intake or exhaust restriction,flow, a few extra fractions of an inch of valve lift, a better or worse multi angle valve job and your up or down 60-80 hp...

    The answer to selecting the proper valve length in relation to the cam lift, and valve spring load rates, depends on the engine valve train geometry and the cylinder head design,
    it differs from intake to exhaust on most engines also.
    I've usually found longer valves are required if the valve lift exceeds about .630, but theres no rock solid rule, you need to do some research and call your machine shop and the cylinder head manufacture. the load rate also plays a significant part in that decision, thinner valve spring seats, is not always an option, as higher load rates require thicker castings for structural rigidity.
    valve lift alone withing reasonable limits, has little to do with the need for longer valves, but as the lift increases the difference between the spring installed height and its spring bind or coil stack obviously changes.
    if your standard valve spring has lets say a 1.70 installed height and a 1.20 coil bind or stack height you would generally be looking at .500 difference, subtract the .060 minimum clearance,
    added to prevent binding issues for coil bind, that only leaves you .440 useful valve clearance.
    now you can machine the heads in the valve spring seat area only minimally as the valve spring seats are over the coolant passages and generally ,
    the manufacturers will tell you you can only machine the valve seat so far from the O.E.M. original location,
    and in many cylinder heads you can't machine deeper without reducing the heads functional strength or causing problems.
    if you can,t machine down into the valve spring seat, your other option is a longer valve stem, or if you just need about .040-.050 maybe you get by with off-set valve locks, or retainers, and longer push rods and valve lash caps.
    but most machine shops would prefer the longer valves and longer push-rods to maintain the proper valve train geometry.
    valves are generally available . .100,..200, .300 longer lengths for popular engines and you can certainly use a micrometer to measure similar valves from a different engine, if the proper length is not easily available.
    be aware that theres both different valve stem diameters, valve lock location, valve lock designs, different intake and exhaust valve steels that you can,t interchange.
    one of the old performance tricks some guys used to use on a BBC, engines with turbos, was to replace the 1.88 exhaust valves with 2.00 intake valves from a 430 lincoln engines that were made from exhaust steel.

    keep in mind all that metallic trash, cycles through the oil pump BEFORE it reaches the oil filter




    before as cast



    notice the more aggressive cam lobe acceleration rate on the roller cam lobes
    notice the stepped cam nose to fit retainer plate


    a good hydraulic roller cam and lifters costs a good deal more
    example cam $280 lifters $297

    or more cam $320

    viewtopic.php?f=55&t=58&p=36446#p36446 lifters $499 lifters $635


    having a REV-KIT that retains the lifters in their bores, to maintain oil pressure, even if the rocker comes loose or push rods breaks is a good idea

    no mater what roller cam you select, youll need to get ,
    the valve train geometry, clearances and spring load rates correct,
    youll ideally want to get the quench distance in the .040-.042 range ,
    port match the intake selected to the heads, and do all the other related checks and clearancing.
    keep in mind scavenging the cylinders correctly requires a properly designed set of headers,
    and open or at least very low flow restriction exhaust
    Tech Tip - 2008

    Roller Lifters: Keep 'Em Rolling Longer

    Most racers are aware of the advantages of Roller Lifters. For those who are not, a brief review is in order. Roller Cams & Lifters are employed today in all-out racing engines where valve lift/area requirements preclude the possibility of employing a flat tappet (solid lifter cam). Higher Lift requires higher valve spring loads (pressures) and flat tappet cams can only handle so much. Additionally, increased rates of lift (cam lobe velocity) above .007" per degree for example on an .842" diameter G.M. lifter, would cause the lobe to reach-out over the edge of the lifters' cam face. Consequently, with either too much spring or too high a lift rate, most racers know that extremely radical flat tappet cams will eventually self-destruct.

    But, what about Roller Lifters? Are they as indestructible as many believe? How do we prolong the life of their roller bearings in today's modern race only engines? Roller lifters require special care and maintenance if they are to provide good service life. Here are the 4 most important factors you should consider to insure their success.

    1. AVOID DRY "START UP": Roller Lifter Bearings are assembled with a "tacky" rust-preventing grease that is not intended for lubrication. Therefore, new lifters should have their roller bearings thoroughly washed in clean solvent or acetone to completely remove this assembly grease. After air drying, premium motor-oil (non-synthetic) such as Penzoil SAE 25W50 GTP Racing Oil (The best of the mineral based oils) or Amzoil "Red" Racing Oil (synthetic) should be used to pre-lube the bearings just before installation.

    2. AVOID "OVERLOAD": Increased load always means reduced service life. Want 50% more thrust from a jet engine? Ask Rolls Royce or G.E. and they'll tell you to expect about ¼th the service life between overhauls. Similarly, employing drag race valve springs in the 900, 1000 to 1100 lb. Range will reduce the life of your roller bearings between rebuilds much the same as will employing high-impact roller cam profiles.

    3. EMPLOY A REV KIT WHEN POSSIBLE: The primary advantage of Camfather Ed Isky's invention of the 1950's is that by pre-loading each Roller Lifter Bearing to its respective cam lobe, you eliminate needle roller bearing "skew". Skewing (the momentary mis-alignment of the bearings' needle rollers to their respective races) is provoked by the start-stop skidding action of the roller bearings each time the lash is taken-up. Eliminate it and you extend roller bearing life dramatically! Unfortunately, many engines such as the Big Block Chevy which could use one the most, don't lend themselves to such an installation because of the severe angularity of the pushrod coming out of the lifter.

    4. EMPLOY LIFTERS WITH "PRESSURE-FED" OIL TO THE NEEDLE ROLLER BEARINGS: Hope is a good thing. But hoping oil will eventually find its way to your Roller Lifter bearings is not. Unfortunately, most roller lifters on the market do not pressure feed oil to the needle rollers, depending on the "splash & a little luck" system instead. In contrast, all Isky Roller Lifters feature pressure fed oil to their roller bearings. Isky's Top of the line "Red Zone" Series lifters feature an exclusive 3-Point "Multi-Port" oiling system to constantly bathe the needle rollers with cooling lubrication. Additionally, they feature our famous Marathon Roller bearing with the toughest shock absorbing heavy duty outer bearing race on the market for the highest possible load carrying capability and sustained Hi-Rpm Endurance. And, they're fully rebuildable, making them your best long-term value!

    back to top
    read thru this info, in the links below ... index.html ... prd100.htm ... index.html

    viewtopic.php?f=70&t=1701&p=4159#p4159 ... index.html ... index.html

    you should also keep in mind that a roller cam valve train with the same lift and duration as a flat tappet cam, can provide a good deal more port flow potential and resulting power, , how much more power is mostly the result of how much more port flow and volumetric efficiency you can get from the engine combo that the flat tappet cam will not be able top access because the valve opens longer per degree of rotation on the roller cam lobe and the lift and duration,the valve sees increases, roller cams have a far lower percentage of lobe wear and less friction, both tend to result in more usable horsepower.
    now if your current flat tappet cam is providing most of the engines potential then the roller cam will only provide a mild improvement, but in most cases you can expect a 15hp-40 hp gain, (depending on displacement, port flow,exhaust scavenging etc,)over a similar flat tappet design with similar duration at .050 lift, but in many case the roller cams peak lift will be noticeably more.
    within certain limits ,the larger the lifter diameter the faster the cam lobe acceleration ramp can be, chevy has a lifter diam. .842
    ford uses a .874 diam, Chrysler .904 diam.

    while all cam timing figures will vary this might help

    but if your willing to pay for special cams and insert solid flat tappet lifters from the cam tunnel , or botton crank case side of the block while its inverted on the engine stand before the cam shaft is inserted holding them in the lifter bores, you can use mushroom base race lifters in a chevy, this allows you to gain the benefits of the larger chrysler lifter diameter while maintaining the stock lifter bore size, but its generally only done on race engines that see frequent maintence tear downs for inspection.


    notice its right where the roller cams lobe design maximized the extra air flow potential that is the most effective flow area during the whole valve flow curve
    and yes it frequently helps to match a roller cam to roller rockers as the reduced friction further helps the engines durability and ability to easily cope with faster valve train component acceleration, that tends to reduce heat and wear.
    The following equation mathematically defines the available flow area for any given valve diameter and lift value:
    Area = valve diameter x 0.98 x 3.14 x valve lift
    Where 3.14 = pi (π)
    For a typical 2.02-inch intake valve at .500-inch lift, it calculates as follows:
    Area = 2.02 x 0.98 x 3.14 x 0.500 = 3.107 square inches, thus it makes a great deal of sense to push the valve lift a bit over .500, and have an intake port that is at least 3.2 square inches in cross sectional area, if you want to maximize flow on a 2.02" intake valve


    the slight bevel on the cam lobe and the slight convex surface on the lifter base in combination with the lobe center-line being slightly offset from the blocks lifter bore results in the lifter rotating in its bores as the lobe rotates under the lifter base

    but even roller cams can wipe out lobes if the valve train components or valve train lubrication,and geometry is not set up correctly

    a quality hardened cam with proper lube won,t wear like this first two picture's, but notice the lifter stayed on track

    hardened cam lobes and high quality hardened roller lifter wheels have very low rotational friction,
    and as long as the valve train stays in its designed limitations and the inertial loads don,t over come the valve springs ability to maintain constant lifter to lobe contact,
    and theres a constant bath of cooling oil flowing over the contact areas,
    rates of lifter to lobe contact and wear are minimal or basically non-existent over any reasonable time frame
    drilling the pass side oil passage plug with a 1/32" bit so oil constantly sprays on the timing gears, and cam retainer plate areas helps extend chain and gear life.


    Comparing Cam Lobes – The roller camshaft (on the left) has steeper opening and closing ramps which allows for more time at max lift.

    heres two similar hydraulic performance cams

    heres a flat tappet with 246 duration and .500 lift ... il&p=23763

    heres a hydraulic roller with the same 246 intake duration with a .558 lift ... il&p=24185

    BTW if your thinking about getting those stamped steel, roller tip rockers , DON,T!!, they have a tendency to fail, and they don,t handle high spring pressures well, and they don,t reduce friction much so they are basically a (FEEL AND LOOK GOOD" part that doesn,t do much constructively[/color]

    Because, easily 90% PLUS of the friction in the valve train is NOT on the contact between rocker arm tip and the valve stem, so swapping to a roller tip on a rocker provides negligible benefits in friction reduction.
    you can buy decent quality full roller rockers, for well under $250-$300
    and roller tip rockers commonly cost 1/2 or more of that making the full rollers a much better option
    the required stall has little to do with the type of lifter your using, its need, to be used, or changed is determined by the rpm range of the cam you select and your car weight,the cars automatic transmission first gear ratio, tire diameter and rear gear ratio.
    a mild roller cam would work with a stock stall converter just as a mild flat tappet lifter cam will.
    the whole idea of swapping to a higher stall speed torque converter is to allow the engine UNDER LOAD to jump in rpm up into the engines most efficient power range or the most effective part of the torque curve.
    Last edited by a moderator: Sep 1, 2018
  2. kelley555

    kelley555 Member

    In the old days it was normal to run a 11:1 c.r. for a street car.The pump gas back then would support that c.r. They used the regular lobe cams with,not so steep ramps,that bled off cylinder psi.Today,you see lower compression engine making big horsepower with hydraulic roller cams.They kinda fake or make similar cylinder psi as the higher c.r. because the ramps on the hyd. roller are steep/fast. A regular hydraulic or mechanical cam only wishes it could run on those steep ramps. All the manufacturer's went to the hydraulic roller engine's,why,cause they ran more friction free/better mpg & made a ton of power at a lower compression ratio using our junky gas's of today.Certainly the hyd. roller setups cost wasn't the reason,they're more expensive.If one wants to make power on pump gas & in a lower c.r.engine,then a hyd.roller cam engine is the way to go.So,you get what you pay for when you try to cut expense's from the regular cam to the hyd. roller cam.That's were most old school guys get in trouble & get lured away from the close tolerance higher billet retro lifters.Even the Edelbrock Performer Rpm Series Billet lifter(1500-6500rpm) look like a Morel to me.Who wants to spend a lot on a engine,then cut a $150-$200 corner.Edel. are great lifters,a little heavier than the Crane billet ,but not even a comparison to the one's made cheaper imported. Cold cast technology Retro Hyd.Lifter,sounds like a cast lifter to me.I guess if one would use cast pistons in their engine,they'd probably match it with the hydr.cast roller lifter's anyways.As Grumpy would says,if you control the valve train with good billet hyd. roller lifter's & sufficient valve spring psi,there's a good chance you won't see the DREADFUL "valves tapping a piston".Later Jr
  3. grumpyvette

    grumpyvette Administrator Staff Member

    Re: is a roller cam worth the extra cost vs a flat tappet de

    Moving Up to a Hydraulic Roller Cam

    One of the quickest ways to gain a significant performance boost is to move up to a hydraulic roller camshaft. This conversion gives you a lot of advantages over a standard hydraulic cam.

    The advantages of a roller cam include: no need to break-in the cam on initial startup, the lifters can be reused if you change cams, the open and close ramps of the lobes are faster, giving you more torque and horsepower for any given grind, roller cams wear at a fraction of the rate of standard cams, and roller cams can use the latest blends of motor oil with out the zinc, so no additives are needed.

    A few things are different about a roller cam installation. A standard cam is ground in a way that causes the lifters to rotate during operation to minimize wear. This design causes the cam stay in place by itself as the engine turns. The roller cam design does not need to rotate the lifters, so it will “float” in place during operation.

    To keep the roller cam from moving too much, you need to use a cam button between the cam cover and the cam gear to hold it in place, and a Torrington bearing behind the cam gear to keep the cam gear from damaging the block. You will need to set a camshaft end play by using shim washers (similar to setting crankshaft end play). Lastly, you need to make sure that your distributor drive gear on the cam, and the drive gear on your distributor are compatible.

    Roller cams are hardened steel, and if mated to a soft iron distributor gear, it would wear out the distributor gear quickly. Most cam makers press on a soft iron gear on the camshaft at the factory, so in many cases you need to do nothing. However, if your roller cam has a hardened gear, the cam manufacturer usually sells a matching hardened steel distributor gear for you to use.

    If you are retrofitting an older engine that did not use a roller cam from the factory, you will need to use a retro fit roller cam and retro fit roller cam lifters. These parts have the correct geometry to go into an older engine and have their own unique part numbers. Also, you will need to use shorter pushrods for a roller cam, and the manufacturer will have the correct length ready for you. If your engine is newer and has a roller cam from the factory, you will use a roller cam and lifters that are designed as direct replacements. Roller cams will work with any rocker arm design.

    Going to a roller cam upgrade is one of those few times where you can really tell the difference it makes when you drive. Roller cams are more expensive, but if you can convince your customer to come up with a few extra bucks, it will really be worth the investment.
    – Tech Tip courtesy of Summit Racing


    The new buzz for hot street engines are hydraulic-roller cams. These cams offer significant advantages for additional lift and more power when properly combined with the rest of the engine combination. That's what has everyone so excited. But there are some practical pitfalls that you should be aware of before you dive in the roller-cam pool. That's what this story will detail. The big limitations are cost and all the other details that must be accomplished before you can take advantage of everything that hydraulic-roller cams have to offer. Let's jump in and see just how deep the waters are, shall we?

    Check What's New With The 2018 Acura MDX
    In the Beginning

    Top Searches
    • [​IMG]3/14
      Hydraulic-roller cams (top) are generally built on harder camshaft cores to withstand the higher unit loading pressure of a hardened roller follower. Flat-tappet cams (bottom) are generally hardened cast iron. This is the main reason why roller cams are more expensive.

      Hydraulic-roller tappets are 0.630 inch taller than hydraulic flat tappets. The factory compensated by increasing the height of the roller-tappet boss in the block. This increased height also means hydraulic-roller tappets are also much heavier and therefore harder to control at high rpm.

      In order to use a hydraulic-roller cam in an early (pre-'87) engine, you must use aftermarket retrofit lifters that use a tie-bar system to prevent the lifter from rotating in its bore.

      Roller cams must also not move more than 0.005 inch fore or aft in the block. This roller-cam button is the way to go and fits inside the center hole in the cam gear.

      The easiest way to check cam-thrust clearance is with a dial indicator on the back of the cam accessed by removing the rear cam plug. The cam-thrust bearing must not deflect the timing cover.

      The elegant solution is a two-piece front timing-chain cover from Bow Laws Products (BLP) or Comp Cams that also offers an access hole for the dial indicator as well as the ability to easily access the timing chain and gear.

      If you don't want to invest in a trick timing-chain cover, Edelbrock's aluminum water pumps come with these thrust-limiter mounts that allow you to install a threaded stud to contact the tin timing-chain cover to prevent deflection.

      Factory hydraulic-roller-cam blocks use this tin "spider" to place a load on the cast retainers that fit over the stock roller lifters. The spider bolts to three threaded bosses cast into the center of the lifter valley.

      When using a roller cam with a mechanical fuel pump, you must use an aftermarket fuel-pump pushrod that offers one of several tips to prevent wear on the steel cam. Comp offers a ceramic tip, bronze tip, or roller-tipped fuel-pump pushrod for these applications.

      Pushrod length changes dramatically when converting an older block to hydraulic-roller lifters. Comp Cams' retrofit hydraulic-roller tappets use a 7.300-inch pushrod length while stock flat-tappet engines generally employ a 7.800-inch pushrod. OEM roller-cam engines spec a much shorter 7.200-inch pushrod. As you can see, it pays to pay attention to pushrod length.

      Swapping in a hydraulic-roller cam also requires bigger and better valvesprings. Assume you will need to run a 1.440-inch diameter dual spring with good retainers and 10-degree machined locks.

      All factory hydraulic-roller-cam blocks employ a step on the front of the camshaft to locate the camshaft behind the factory thrust plate. With the step face, the cam is intended for a hydraulic-roller-cam block. These cams can be used in earlier blocks but will require using a modified late-model thrust plate with the ears removed.

      Virtually all street hydraulic- and mechanical-roller cams now come from the major cam companies with iron gears pressed onto the end of the camshaft to allow the use of stock-type iron distributor gears instead of the softer and less durable silicon-bronze gears.
    Last edited by a moderator: Mar 26, 2018
  4. grumpyvette

    grumpyvette Administrator Staff Member

    Re: is a roller cam worth the extra cost vs a flat tappet de

    these two above make good cruising cams in a 9.5:1-10:1 cpr 383 and all require converter and rear gear changes to maximize the results

    these two above make good performance upgrades in cars used for daily transportation if your willing to put up with a lope in the idle and some loss of low rpm torque in exchange for more power higher up in the rpm band cams in a 10:1-10.5:1 cpr 383 and all require converter and rear gear changes to work correctly

    all these cams below make good performance upgrades in cars used mostly for weekend toys with less and less compatibility for use in daily transportation if your willing to put up with a lope in the idle and some significant loss of low rpm torque in exchange for much more power higher up in the rpm band cams in a 10.5:1-12:1 cpr 383 and all require converter and rear gear changes to work correctly or even function in most cases



  5. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    By David Reher, Reher-Morrison Racing Engines

    “A low-tension valve spring and a heavy steel valve is the worst possible combination for high-rpm reliability.”

    Faithful readers of this column know that my mantra on engine building is to spend your money wisely. Sometimes that means writing a bigger check initially in order to save money in the long run. A case in point is the decision whether to use flat tappets or roller lifters. In my view, a flat tappet is a ticking time bomb in a racing engine. Sooner or later, that bomb is going to explode with expensive results.

    I’ll climb up on my soapbox and tell the drag racing world that a flat tappet camshaft is a bad investment for any serious competition engine. A typical flat tappet valvetrain may have a lower up-front cost than a roller camshaft, but it’s going to cost much more over the engine’s lifetime. The odds are that a flat tappet camshaft is either going to fail outright or cause a dropped valve. In either case, you’re looking at a thoroughly trashed engine and a major repair bill.

    I know that some racers have run flat tappet cams successfully for years, and that NASCAR Nextel Cup teams are required by the rules to use flat tappets. The former are very fortunate, while the latter spend mountains of money on special cam cores made from exotic alloys, hardened and inlaid lobe faces, oversize zero-radius lifters, camshaft oilers and major block modifications to eke out 500 miles of racing from a flat tappet cam before it self-destructs. Flat tappets don’t save money for NASCAR teams – in fact, the total cost far exceeds the price of a roller cam and lifters. Moreover, the highly specialized components and machining procedures used in NASCAR Nextel Cup engines have virtually nothing in common with the flat tappet cams listed in retail catalogs.

    Flat tappets survive in street engines because the valve spring pressure is relatively low. Consider that the seat pressure for a stock small-block Chevy V-8 with a flat tappet cam is 85 pounds. The generally accepted maximum spring pressure for a flat tappet cam used in competition is 130 pounds. That’s still much less than the 300+ pounds of seat pressure typically used with roller lifters in racing engines. Moreover, a low-tension flat tappet valve spring and a heavy steel valve is the worst possible combination for high-rpm reliability. The valve’s inertia can easily overcome the weak valve spring tension, producing violent, uncontrolled motion that can lead to a dropped valve and catastrophic failure.

    Installing a flat tappet cam correctly demands considerable effort by the engine builder. Doing the job right requires making sure that every cam lobe is precisely positioned in relation to its respective lifter. The lobes on flat tappet camshafts are intentionally ground with a slight taper that causes the lifters to spin; if a lifter doesn’t rotate because of improper offset, the resulting friction will quickly destroy the lobe. The metal worn off the cam lobe is then embedded in the piston skirts and cylinder walls, causing scuffing and serious cylinder wall damage.

    In contrast, a roller lifter can tolerate slight misalignment in the position and angle of the lifter bores. A roller bearing also requires much less lubrication than the sliding base of a flat tappet, so the amount of oil circulating in the engine can be reduced to minimize windage losses.

    A flat tappet severely limits the camshaft profile and thereby restricts the engine’s performance potential. The diameter of a flat tappet dictates how quickly the valves can be accelerated. Years ago engine builders replaced standard .842-inch diameter GM lifters with larger .940-inch tappets and special mushroom lifters because the increase in lifter diameter allowed more area under the lift curve. But even the fattest flat tappets can’t produce the same valve acceleration as a standard diameter roller lifter. Consequently flat tappet cam profiles have long seat timing that bleeds off cylinder pressure without delivering the breathing benefits of increased duration.

    In my experience, the people who tend to favor flat tappets are either newcomers to racing who are trying to save money or veterans who had a bad experience with roller lifters in the distant past. I think that both groups are making a grave mistake by not using a roller cam unless they compete in a class that specifically requires flat tappets. Yes, a roller cam and kit does cost more than a flat tappet cam and a set of lifters, but the cost of fixing an engine after flattening a cam or dropping a valve is much more expensive. It’s true that a roller lifter may fail occasionally – usually as the result of a broken valve spring or incorrect valve lash adjustment – but the likelihood of trouble is much less than with flat tappets.

    I’m a frugal person, as anyone who has seen our Pro Stock racing operation can attest. My philosophy on engine building is that it’s much cheaper to do a job right the first time than to do it wrong and then fix it. It always costs more to repair something, and generally the effort and expense are a lot more than you ever imagined. For my money, flat tappets belong in the museum, not on the race track.
  6. 87vette81big

    87vette81big Guest

    I read earlier today Grumpy.
    All I have ever used is in my Own Pontiac V8's is a Flat Tappet Camshaft profile.
    And I prefer Flat tappet Solids.
    Never had a cam lobe fail yet on me.
  7. Strictly Attitude

    Strictly Attitude solid fixture here in the forum

    interested to know Solid Flat Tappet Vs. Hydraulic Roller would like to run a solid mechanical but they are not very durable and I do not have 800 to a thousand to spend on bushing rollers. I really would like to give the engine a little life with out having to tear down and inspect every year or every other year. I do not have my own garage or that would not be a big deal. I feel that is why you see so many solid roller lifters on eBay. I really want a mild Solid Roller but it would from my investigation need the lighter spring pressures to survive. As they seem to be the #1 culprit on killing the lifters. If I did not daily drive my car most of the summer I would be ok with that but seems I would be testing fate. The bushing Lifters would at least if you have a failure just take out your $400 camshaft have to replace a lifter or just have them all rebuilt. If it was cost effective as in I could have them rebuilt once every two years for like $200 I would run it all day long. These are the tough decisions we have to make wanting max performance from our engines.
  8. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    Strictly Attitude
    yes thats the issue in a nutshell, most performance solid roller cam profiles are designed to operate at least,
    1000 rpm-2000 rpm higher than a hydraulic roller cam with similar duration,
    and the solid roller cam generally has a slight extra lift added, and they are designed too.
    use acceleration ramp designs that require,much higher load rates to maintain valve train stability.
    most manufacturers will list the ideal intended valve spring load rates and clearances the cams designed to be run with,


    The following recommendations are from Erson Cams. If you have questions, you can reach their tech department at 800-641-7920.

    Hydraulic Flat Tappet Camshaft: 110 lbs Seat pressure/250-280 lbs open pressure

    Solid Flat Tappet Camshaft: 130 lbs Seat Pressure/300-325 lbs open pressure

    Hydraulic Roller Camshaft: 130-140 lbs Seat Pressure/300- 355 lbs open pressure

    Solid Roller Camshaft: (Minimum Safe Pressures DEPEND ON SEVERAL FACTORS)

    Up to .600  valve lift: 200-235 lbs Seat Pressure/600 lbs open pressure

    Over .600  valve lift: 250-280 lbs Seat pressure / and 100 lbs pressure for every .100  of valve lift

    use of a heavy valve spring load rates,
    too control the valve train at the upper rpm range,
    (generally thats going to be 7000 rpm or above )
    and you rapidly increase wear on the contact areas,
    so guys that have, installed those solid roller cams are,
    forced to make a choice.
    if you fully intend to operate the engine above, and beyond about 6500 rpm you'll be forced,
    to use the higher load rate valve springs to maintain valve train stability.
    but keep in mind the solid roller lifter design is generally significantly lighter weight than a similar hydraulic roller so inertial loads are lower.
    hydraulic roller lifters generally weight about 20% more than a solid roller lifter

    thus a solid roller lifter valve spring could at least in theory, have slightly less load or spring pressure,
    and still allow valve train stability at rpm levels that the similar hydraulic roller cam would be expected to operate at,
    if the cam lobe acceleration ramp designs were similar.
    you can significantly reduce wear and extend a solid roller cam valve trains durability and expected life span IF you run lower valve spring load rates PROVIDED your going to limit the engine operational rpms or power band to keep the valve train well within the lower limits those lower valve spring load rates provide valve train stability..... but that generally brings the power band down into the operational range where the better hydraulic roller cams can equal the performance so its a trade off.
    at some point the solid roller combo should provide more power and less potential stress due to the lower over all valve train mass and inertial loads and more aggressive lobe design, but at the risk of loss of valve train stability.
    THERE IS A difference in strength between cast and billet cam cores and of course the cost of the components, a hardened billet cam core is structurally about 30%-50% stronger than a similar cast cam core and less likely to break, as it can absorb slightly more abuse.
    now and valve train must constantly be bathed in a waterfall of high quality, clean, cooling oil flow, and lifters pressure fed oil from the lifter galleries if they are expected to survive ,
    then theres component quality issues and the fact that no cast core cam can realistically be expected to handle the much higher stress and inertial loads , and constant impact loads, that the heavy valve spring load rate impart indefinitely nearly as long as a hardened billet core cam will, the physical strength is just not the same.
    its a combination of both rpms (and the related inertial loads)and valve spring load rates and cam lobe acceleration ramp design,that tend to cause wear on cam lobes.
    Ive generally said that valve springs seat loads over about 200 lbs and open loads over about 450 lbs are best matched to a billet cam core on roller cams, if your running lower seat and open valve spring load rates a hardened cast cam core will work ok on a roller cam application

    related info;
    Last edited: Dec 29, 2016
  9. DorianL

    DorianL solid fixture here in the forum Staff Member

    Grumpy, I am assuming that if I want to build a torquey 383 with an excellent idle of 18-22 inches and TBI… you can squeeze out more torque and power all the while preserving those characteristics… so even with the very streetable build I have in mind there are performance gains to be had by going roller…
  10. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    if your looking to maintain enough vacuum for power brakes, and proper TBI sensor use,

    when you build that 383 SBC ,its going to require selecting a reasonably mild cam on a wide lsa,
    you can certainly get respectable low and mid rpm power if the compression levels up, near 9.5:1
    but it will limit peak power noticeably at anything much over 5000 rpm
    If your intention is to build a high torque 383 sbc for daily driver use, but still get fairly brisk performance,
    cams like these, ( below), benefit noticeably from the use of 1.6:1 ratio rockers and high flow rate cylinder heads,
    in the 180 cc port range, and long tube headers with a low restriction exhaust,
    and ideally a 3.55:1-3.73:1 rear gear and an over drive transmission like a 200r4 or 700r4


    obviously have a talk with the tech guys at your manufacturer's of choice.
    Last edited: Dec 29, 2016
  11. Strictly Attitude

    Strictly Attitude solid fixture here in the forum

    the recommended springs for the cam I was looking at was 175 seat and 350 open rate 320 my cam spec would be at 244@.050 284 advertised it is on a 108 but would order on a 106 it is single pattern and billet like I said if I can come up with a schedule to keep it healthy and running I might go that route as the spring rates are not overly crazy and it would maximize HP and TQ through my desired RPM range.
  12. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

  13. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    Strictly Attitude
    " 175 LB seat and 350 LB open spring rate "
    you seem to list,
    seems like its a bit high on the seat load rate, to me
    most hydraulic roller cam valve springs fall closer too.
    Hydraulic Roller Camshaft: 130-140 lbs Seat Pressure/300- 355 lbs open pressure
  14. Strictly Attitude

    Strictly Attitude solid fixture here in the forum

    That is a solid roller Grumpy that I am pondering running, comes with the cam retainers rev kit pretty much everything necessary to run that cam. But it is expensive but you get allot for the money. Isky $1535 included in purchase cam, lock plate, springs, retainers, distributor gear, thrust bumper, pushrods, rev-kit, redzone lifters, would see if I could get them upgraded to EZ roll as they are about $85 difference in price from the redzones. I am still investigating to make an educated decision. I have noticed allot of failures read about are BBC which is a larger lift and higher spring rates. Also guys that make them survive service them an keep a good eye on lash. I am not sold one way or another yet.
  15. Loves302Chevy

    Loves302Chevy "One test is worth a thousand expert opinions."

    Did I miss something here? That cam is too big to work with TBI (244 deg@.050"), and that tight lobe separation (106, 108) will never give you 18-22" idle vacuum.
    The "smallest" solid roller cam you might find is still to big for your desired usage.

    OK. I see now. 2 different guys, 2 different engines. Sorry.
    Last edited: Dec 29, 2016
  16. DorianL

    DorianL solid fixture here in the forum Staff Member

    That was kinda what I was getting at tho'
  17. Strictly Attitude

    Strictly Attitude solid fixture here in the forum

    I am pretty sure I am going to go to hydraulic roller at this point it will have to be a custom cam that will be on the border of having to go solid but I will keep the rpms under 7000. I will spend a few more hours on performance trends playing with the curves I really need to measure my runner lengths on that intake. I am still on the fence though I will match something nice up to tie it all together.
  18. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

  19. Loves302Chevy

    Loves302Chevy "One test is worth a thousand expert opinions."

    Comp Cams does not recommend solid roller camshafts for street usage.
    I just read this yesterday, I think from one of Grumpy's links.
    Nope, it was in the March 2017 issue of Chevy High Performance.
    But I can't find a link. It must not be published yet. So I will type it out.

    ..... (solid roller) was not designed for extended low-rpm operation.
    ..... (hyd roller) excessive spring pressure may damage the hydraulic roller lifter, so a balance
    must be met between spring pressure, longevity, and desired rpm. The advent of limited travel lifters
    (that reduce the reservoir and plunger movement) combined with cam profiles allow for hydraulic roller
    cams to exceed 8000 rpm, so hydraulic rollers are certainly bridging the gap with solid rollers. The solid roller
    cams increase valvetrain noise, require periodic adjustment, are not suited for (low-rpm) street use......
    Leave the solid roller stuff for dedicated race engines, and by that we mean very high rpm or very high boost stuff
    that requires excessive spring pressure.
  20. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    Id have to agree with that assessment on the whole, but the valve spring load rates required too allow a hydraulic roller cam to get to 8000 rpm will match or exceed the load rates on a solid roller lifter, basically making the hydraulic lifter almost non-functional

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