Selecting Your Valve Spring
With all of the choices in aftermarket cylinder heads and valve train components, calculating the required valve spring rate and seat pressures would be impossible without knowing specific properties of each of your components. So, we offer the following guide lines for you to select your valve springs.
"FLAT-TAPPET" seat pressures 110-135#
"FLAT-TAPPET" Open pressures should not exceed 330# (after spring break-in) for acceptable cam and lifter life. Open pressures should be a minimum of 260# for lifts around .500”, 290# for lifts around .560” and a minimum of 300# for lifts at or above .600”. Spring open pressures over 280# can cause "pressed-in" studs to come loose. So…?
“HYDRAULIC ROLLER” seat pressures 135-165#, Max 170#
“HYDRAULIC ROLLER” Open pressures 300-375#, Max 425#
Note: Open pressures in excess of 360# require hydr roller tappet bodies made of billet steel.
“SOLID LIFTER ROLLER” Seat pressures minimum 180-200#, most common 220-250#, we recommend that you seek experienced professional assistance on your profile designs and spring choices for Pro-stock and Blown Alcohol/Fuel drag applications that can use up to 340-370#.
"SOLID LIFTER ROLLER" Open Pressures need to be high enough to control the valve train as the lifter goes over the nose of the cam. Ideally, the minimum amount of open pressure to eliminate or minimize valve train separation is desired. Any excess open pressure only contributes to pushrod flex, which can aggravate valve train separation. For serious racing applications this can be determined only by experimentation and track testing. For general guidelines we offer the following:
“Street/Strip Performance” with long life expectancy, 350-450#.
"Circle Track" and "Moderate Bracket Racing", 450-600#.
"Serious Drag" and "Limited Distance Circle Track", 600# and up.
TIPS AND GOOD INFORMATION TO KNOW
One of the easiest and sometimes most costly mistakes made in racing engines is not positively locating the spring. A valve spring that “dances” around on the cylinder head or retainer causes harmful harmonics and excessive wear. A spring that is forced onto a retainer is likely to fail at that coil. A spring that is contained properly at the retainer and the cylinder head will offer the longest possible service life.
Handle springs with care. Never place in a vise, grab with pliers or hit them with a hammer. This will damage the surface of the spring, which will cause a spring to fail.
When separating double or triple springs, use only a durable plastic object that cannot harm the shot-peened surface of the spring. Never use a tool or hard metal object like a screwdriver.
Valve springs are shipped with a rust preventative coating that should remain on the spring throughout engine assembly. Do not clean springs with acidic or evaporative cleaners. This causes rapid drying and promotes the formation of rust on the surface, which can cause catastrophic failures. Even a slight amount of corrosion can grow to be a problem.
It is important for new springs to take a heat-set. Never abuse or run the engine at high rpm when the springs are new. Upon initial start-up, limit rpm to 1500 to 2000 until the temperature has reached operating levels. Shut off the engine and allow the springs to cool to room temperature. This usually will eliminate early breakage and prolong spring life. After the spring has been “broken-in”, it is common for it to lose a slight amount of pressure. Once this initial pressure loss occurs, the spring pressure should remain constant unless the engine is abused and becomes overstressed. Then the springs must either be replaced or shimmed to the correct pressure.
Everything we covered on this web page should only be considered as general guide lines and "rule of thumb" values. Experienced valve spring professionals should always be consulted.
2017 CUSTOM CAM PRICING
HYDRAULIC F.T. $244.98 ADDITIONAL COSTS
RACING HYDRAULIC F.T. $258.98 PS DRIVE in rear of cam $50.00
MECHANICAL F.T. $258.98
HYDRAULIC ROLLER ( SADI CORE ) $365.98
HYDRAULIC ROLLER ( 5151/5160 I.H. ) $415.98
HYDRAULIC ROLLER (8620 CARBURIZED) $455.98 SOME CORES MAY NOT BE AVAILABLE
MECHANICAL ROLLER (5151/5160 I.H.) $425.98 FOR ALL ENGINE TYPES
MECHANICAL ROLLER (8620 CARBURIZED) $455.98
ON ANY OTHER CORE MATERIAL CALL FOR PRICING
OVERSIZED JOURNALS CALL FOR PRICING
To place a cam order you will need to fill out and submit the order form below, but also send an email to firstname.lastname@example.org with your "*.S96" files and "*.CI8" Engine Design file (as attachments). Once we receive your order form and files, we will revue your information and contact you by phone if any changes are required or we have any concerns about the profile designs. After we accept the order, we will then send you a DJRC invoice via email, payable through Paypal. The invoice total will include the price of the cam, shipping and any taxes. When we are notified by Paypal that your invoice has been paid, we will place your order with Howards Cams. When Howards Cams has finished your cam, they will ship it directly to you.
Howards Cams will grind your hydraulic flat tappet profiles on HGI 55 cores, while using their high chrome core for all mechanical flat tappet profiles. For roller cams and hydraulic rollers, you have a choice of core material or by selecting "No Preference" can have the correct core choosen for you. If you are not sure what core you'll require, we suggest you choose "No Preference".
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