Conversely, in that regard the 2V motor is at more of an advantage with 2 or 3 speed automatic transmissions and 3 or 4 speed manual transmissions. In summary, as they came from the factory both versions of the C had good low rpm power, good throttle response, and good drivability.
The volumetric efficiency of the 2V cylinder head is excellent, and the 4V cylinder head has tremendous capabilities in that regard. With ratings of horsepower C 2V and horsepower C 4V the volumetric efficiency of both versions of the C was under-utilized.
The engine is equipped with the standard stroke factory crankshaft. The iron 4V heads are ported, the compression ratio is set at , the induction is individual runner with fuel injection, the exhaust is a bundle of snakes type exhaust.
The camshaft is a relatively mild hydraulic roller cam, the Crane HR camshaft. This is actually a very mildly tuned engine with good drivability, yet the power output is tremendous.
Since the cylinder heads were designed to make peak horsepower at rpm the engine didn't need a long duration camshaft to make high rpm power. A lot of money was invested in the induction and exhaust systems, and that investment paid-off. The volumetric efficiency of the iron 4V heads is very high with IR induction, and the bundle of snakes exhaust helps too.
This exemplifies the advantages of a good induction and exhaust system and it exemplifies the capabilities of the 4V cylinder heads. It also exemplifies the concept of improving the engine's performance without diminishing the power characteristic in any aspect.
The "state of tune" was increased by improving the induction system, not by using a "big" camshaft. The design of the 4V cylinder heads gives us this option. The LS7 is 35 years newer, it uses compression, CNC ported heads, a higher lift hydraulic roller camshaft and induction via a modern long runner fuel injection intake manifold.
It displaces 5. Unlike either of these engines, the C was mass produced as inexpensively as Ford was capable, and it was manufactured from lowly cast iron. I consider horsepower a high state of tune for a C, but it doesn't need to run like a drag-race engine to achieve high output The combustion process is therefore the logical place to begin when optimizing an engine or tuning it for higher output.
The parts which influence the combustion process include the design of the combustion chamber, the design of the piston dome, the compression ratio, the seal of the piston rings against the cylinder wall, the seal of the valves on the valve seats, the cylinder to cylinder consistency of the fuel air mixture, the quality of the fuel air mixture better fuel atomization , the cylinder to cylinder consistency of the ignition system and the quality of the spark produced by the ignition system.
The shallow poly-angle combustion chamber of the Cleveland cylinder head is a very good design. It is the most important aspect of the head and the single biggest contributor towards the power producing capabilities of the Cleveland engine, yet people seldom think twice about it. It is not possible to set-up an engine having low compression to provide the type of performance most people are looking for.
The compression ratio of an engine is limited by the octane of the gasoline that shall be used. There are two rating systems for octane being used around the world, many people are unaware of the differences and unaware that low octane "regular" fuel in Europe is high octane "premium" fuel in the US and Canada. Since this is an international forum, its important that we are all on the same page, the information below should help. The aftermarket cylinder heads which are cast in aluminum and equipped with high-swirl combustion chambers are capable of tolerating at least 8.
My preference is to set the dynamic compression of a street engine a little lower than the maximum amount in order to give the engine a margin of safety. For your comparison, the factory Cleveland engines with the highest static compression ratios, i. Following are seven common scenarios for raising the compression ratio of the C. A Word of Caution: Decking the block, milling the heads, installing pistons with greater compression height, or installing pup-up dome pistons increases the importance of checking piston to valve clearance during assembly of the motor, especially with high lift or long duration camshafts.
Pop-up dome pistons will normally require more total ignition advance too. Piston ring thickness and tension creates friction that resists crankshaft rotation.
Decreasing piston ring thickness or tension reduces the energy required to keep the crankshaft rotating, and therefore increases the power available at the rear wheels. The additional cost of high-tech rings over the price of standard cast iron rings constitutes one of the least expensive ways to increase horsepower. Modern thinner or lower tension piston ring sets can offer higher output at the rear wheels and better durability with no penalty in the life of the rings.
That's some relatively inexpensive horsepower. A smooth and precise operating "high output" breakerless ignition system is just as essential to a high performance engine as raising the compression ratio.
There are many ignition systems to choose from. California was the only state in which Ford vehicles were equipped with Duraspark I ignitions; Ford enthusiasts outside of California were not aware of the existence of this ignition and had no experience with its performance, which was a shame.
The Duraspark I ignition was also known within Ford as the "high output ignition", it was much more than a different Duraspark module, it was considered an entirely different ignition system than the Duraspark II ignition system.
It was Ford's first high output ignition system, and Ford's first ignition system to employ "dynamic dwell". The Duraspark I ignition was utilized in all California V8 equipped applications in , and limited to California V8 applications in and At the heart of the Duraspark I ignition was a special ignition coil having a very low primary winding resistance. The coil was also operated with no ballast resistance; therefore current flow in the primary windings was substantially increased in comparison to the primary current of Ford's standard Duraspark II ignition system coil.
The core of the Duraspark I coil was designed to accept a much higher magnetic charge from the increased current flowing in the primary windings, thus producing a substantially higher voltage to the spark plugs. The higher magnetic charge also allowed the coil to reach "full charge" more rapidly than Ford's Duraspark II ignition system coil. Spark intensity was greatly increased If this coil's primary winding had been charged with the conventional "fixed-dwell" control utilized by the Duraspark II electronic ignition system it would have overcharged at low rpm and overheated.
Therefore an ignition module with a unique primary current control circuit was required to compliment this coil. Differing from the various Duraspark II ignition modules, the Duraspark I module didn't control charging of the coil in the conventional way. The Duraspark I module utilized dynamic dwell, meaning the module constantly adjusted dwell based on current flow in the coil's primary circuit, independent of engine speed.
Dwell therefore varied with respect to the degrees of crankshaft rotation but remained relatively constant with respect to actual coil charging time; and the coil was properly charged throughout the engine's operating range. The Duraspark I ignition produced the most consistent and most potent spark of any Ford ignition. The ignition ignited mixtures the Duraspark II ignitions could not. The dynamic dwell feature gave this module good high rpm performance too as the coil was charged properly never under-charged or over-charged from idle to rpm.
Original Post. Cylinder to cylinder consistency of the fuel air mixture is difficult to achieve with a single carburetor, and it is greatly influenced by intake manifold design.
The manifold design must insure that equal amounts of air and fuel are flowing into each cylinder, it must not do anything that may cause the fuel to fall out of suspension, and it should prevent or control fuel puddling. The quality of the fuel air mixture is greatly influenced by carburetor design. Improved atomization of fuel smaller fuel particles insures the fuel stays in suspension, distributes more equally cylinder to cylinder, and ignites more readily in the combustion chamber.
This is one reason why you shall find I emphasize the use of carburetors with annular booster venturis. An individual runner induction system alleviates these concerns. An individual port fuel injection system employing a manifold with long equal-length runners also alleviates these concerns. A throttle body fuel injection system mounted on an intake manifold originally designed for a carburetor atomizes the fuel excellently, but it does not alleviate the concern for cylinder to cylinder consistency, fuel puddling, etc.
I shall touch on these alternatives in this section. In practical terms those things boil down to a larger carburetor with annular booster venturis, an aluminum intake manifold Ford, Edelbrock, Blue Thunder or reworking the factory cast iron intake manifold to accommodate the larger carburetor, and a camshaft that lifts the valves further open with matching valve train improvements. Key valve train improvements include single groove stainless steel valves, higher rate valve springs, stiffer-thick wall push rods, and improvements to the factory rocker arms.
The subject of valve train improvement shall be discussed in additional detail in the valve train section which follows this section. However, as the volumetric efficiency of a motor improves the intake manifold vacuum at wide open throttle shall decrease. The airflow rating of carburetors is measured at a fixed depression, such as 1. If the depression across a Holley carburetor is less than 1.
The reason for this is not because the motor demands more air flow than what we calculated but because the carburetor, which is rated at a depression of 1. For any given quantity of air flowing into the engine a larger carburetor will require less intake manifold vacuum to supply that quantity of air, therefore the intake manifold vacuum at any given rpm shall be less and this allows for higher volumetric efficiency. Both the C 2V and the C 4V have higher volumetric efficiency than the popular in-line-valve V8s people are more familiar with; at wide open throttle the vacuum in their intake manifolds will drop lower than it does in those other V8s if the carburetor is large enough to allow it.
This is the reason larger carburetors are recommended for the Cleveland engine series. If an owner selects parts for the C induction system following the same guidelines people follow when selecting parts for a SBC or SBF the C shall not perform any stronger than a SBC or SBF; the superior volumetric efficiency for which the C is known shall be quenched.
Contrary to the carburetor sizing conventions you may be familiar with the C especially the 4V version is designed to inhale more air than other engines and it responds well to a bigger carburetor. There is no penalty in drivability or throttle response as long as the carburetor is calibrated properly. On top of that the C 4V is capable of operating over an extraordinarily wide power band, certainly wider than any other OHV engine from its era.
The first C 4V performance manifolds designed by Ford were designed for list Holley Dominator carburetors cfm! The Cleveland engines require carburetors designed for engines having higher volumetric efficiency and in the case of the C 4V a wide power band too. The usual carburetor choices for a C 2V usually range from cfm to cfm; for the C 4V those choices usually range from cfm to cfm.
None of these carburetors are too big for a C street motor, especially if they are equipped with annular booster venturis. With a C 4V street motor it is a challenge to find a carburetor that performs well at low rpm while also being large enough to take advantage of the WOT wide open throttle volumetric efficiency of that motor. Annular booster venturis atomize fuel better and provide a stronger fuel metering signal at low air velocity.
In other words, annular booster venturis benefit the low rpm and mid-rpm performance of a motor in the same manner as the smaller primary throttle bores of a spread bore carburetor. These attributes make annular booster venturis popular for improving the low rpm operation of performance engines, where they have earned a reputation for improving torque, horsepower and throttle response at low engine speeds.
The only drawbacks of annular booster venturis include their larger physical size which reduces the airflow capability of a carburetor by a relatively small amount and their greater cost of manufacture. A cfm to cfm carburetor is fine for daily transportation purposes and even a playful bit of acceleration from time to time.
But I don't recommend that choice for the performance minded owner. A C equipped with a smaller carburetor will flatten out sooner when accelerating and lose the eagerness to rev far beyond rpm.
Regardless of what size carburetor you choose, if it is calibrated poorly the motor shall perform poorly, if it is calibrated well it shall perform well. An engine equipped with a well calibrated cfm carburetor will make more horsepower than if it were equipped with a poorly calibrated cfm carburetor; but if the cfm carburetor is calibrated as well as the cfm carburetor then the motor will perform better with the larger carburetor.
For this reason many enthusiast prefer a carburetor having features that make it easier to tune. Single Plane C Intake Manifolds Under Development Dual Plane C Intake Manifolds A dual plane intake manifold is the best choice for a street driven vehicle in terms of overall functionality and usable performance.
The factory intake manifold runners flare open to match the height of the 4V intake port entrance. The gas flow in the factory induction system starts in a runner with a cross sectional area of about 3 square inches, then it expands to a cross sectional area over 4 square inches at the intake port entrance, then past the intake port entrance it returns to a cross-sectional area closer to 3" again.
This is not ideal. One way to achieve an induction system having a more consistent cross-sectional area is to use the Blue Thunder manifold which has full height runners that complement the opening of the 4V intake port; the Blue Thunder manifold was designed to be a "wide open induction system" manifold thus complimenting the engineering of the 4V intake port, it performs very well with the iron 4V heads. Those manifolds can be mated to the 4V heads as-is. Do not blend the runners of the manifolds to match the opening of the 4V intake port; they perform better if they are not blended.
If you wish to eliminate the mismatch and make the cross sectional area more consistent the proper way to do so would be to fill the inlet of the 4V intake port to match the Edelbrock or Scott Cook manifold runners this is also called stuffing the intake port.
In spite of the fact they create an irregularly shaped port the features work very well at increasing flow. Intake manifolds which lift the gas flow within the port so as to avoid these features may actually result in a decrease in gas flow or engine performance. Stuffing the port will definitely decrease gas flow. If you're going to stuff the port entrance then the port should be "ported" further within afterwards to regain the lost port volume, to make the ports cross-section and shape smoother and more consistent, and to regain the flow that was lost by stuffing it.
The port actually works very well "as-is", it doesn't require "fixing". This is why I recommend the Blue Thunder manifold which allows the intake port to operate optimally in the way it was originally designed to do so. The Robb Mc Performance mechanical fuel pump is rated for up to horsepower. Install a high flow fuel "pre-filter" designed for the fuel pump inlet 75 to micron and install a high flow fuel "post-filter" designed for the fuel pump outlet 10 microns for fuel injection or 40 microns for a carburetor.
If you're building a high output motor for a Pantera, this is one item that shall require modification. The picture below details the proper way to plumb a fuel system using an electric fuel pump for both carburetors or fuel injection. The Aussie Speed manifold is designed as a 2V manifold, but it is also designed to seal-up the larger intake port openings of a 4V cylinder head.
It is accepted by very many sports car hobbyists as a suitable replacement for various Delorto and Solex carburetors. The IDF carburetor is offered in 40, 44 and 48 mm bore sizes. The main, idle, air correction and accelerator pump jets, the emulsion tubes and venturis, are interchangeable. It has a float design that makes it very popular for off-road applications, a vacuum advance port, and four progression holes for smooth light-accelerator response.
An IR induction such as this is more expensive to purchase, it is more time consuming to tune, and it often requires more frequent maintenance. However, in comparison to a single four barrel carburetor induction system the benefits of an IR system include quicker throttle response, faster acceleration, a wider power band and substantially improved volumetric efficiency.
Port fuel injection also eliminates the issues of fuel falling out of suspension, fuel puddling, and uneven fuel distribution associated with intake manifolds designed for carburetors. Throttle body fuel injection shall always be a viable option for retrofitting fuel injection to an older engine in terms of simplicity, cost and stealth because it can be installed in place of an existing carburetor, and therefore it does not require the replacement or modification of an intake manifold, it takes up no more room in the engine compartment, and it even uses the same air filter assembly.
Both of these intake manifold kits are an overwhelmingly better way to fuel inject a C in terms of performance compared to utilizing an intake manifold designed for a carburetor. The R-Series intake is a long equal length runner design which is tuned for high performance street engines.
Combining long equal length runners with the improved fuel atomization at low rpm typical of fuel injectors this manifold has the potential to boost the lower rpm power of a C much in the same way this type of manifold boosted the lower rpm power of the 5. This manifold provides a superior way to achieve the type of low rpm grunt that people are trying to duplicate when they build stroker engines. The R-Series intake manifold is claimed to have It is available with either a 75mm throttle body inlet or a 90mm throttle body inlet.
This manifold has the potential to improve volumetric efficiency like an individual runner induction system but only requires one throttle body. The Box-R-Series intake manifold has a 90mm throttle body inlet, and an overall height of The common base used for these manifold kits is finished in bare aluminum, the port outlets are 2. Its hard to give guidance regarding selection of a business to port 4V cylinder heads in broad terms. Do not agree to extreme porting of the 4V heads unless the business has a decades old reputation for porting C 4V cylinder heads; such as Koontz and Company Arkadelphia Arkansas or Valley Head Service Northridge California.
Most "cylinder head porting businesses" do not understand the 4V heads. I've seen C 4V performance worsened by many businesses claiming to be professionals at cylinder head porting. It is healthy to be hesitant and cautious about handing over your 4V cylinder heads to any business for modification. A simple amount of pocket and port clean-up combined with 3 angle valve seats will increase air flow through both the intake and exhaust ports by 50 cfm at 0.
An exhaust system can only perform as well as its weakest link. As mufflers become less restrictive the gains that can be realized by improving other aspects of the exhaust system multiplies.
The higher the output of an engine the higher the gains that may potentially result from exhaust system improvements. The goal is to broaden the tuning of the exhaust system thus improving mid-range power over a wide range of engine speed.
Tri-Y headers aka 4 into 2 into 1 headers pair the cylinders on each bank of the engine so as to provide the maximum separation between exhaust pulses per bank. It is a more practical design for achieving performance goals similar to a bundle of snakes type exhaust system without taking up as much engine compartment space. In other words when space is limited it is better to shorten the primary tubes and lengthen the secondary tubes. After those considerations the most important aspect of header design and the exhaust system as a whole is the tubing geometry; i.
These details have a tremendous impact on the performance of the exhaust system. Any header and exhaust system has to make concessions in its construction to clear various parts of the chassis, the suspension, the steering, the starter motor, the bell housing or the transmission. One particular aspect of header geometry was discovered long ago to greatly impact the performance of the C 4V exhaust port Pantera Exhaust The Pantera chassis does not provide enough space for headers with primary tubes of the proper length.
Nor does it provide enough space for decent mufflers. It is possible to install a cross-over under the car connecting the left and right sides of the exhaust system, but it is almost as long as the intermediate pipes!
The one good thing about the Pantera chassis, it allows enough space on either side of the engine so the primary tubes can extend straight out of the head for several inches. The European GTS exhaust system should be considered a minimum upgrade for Panteras equipped with the "small tube" factory exhaust system. The GTS system is reasonably quiet, with a nice low frequency burble. The headers have the proper size primaries for iron 4V heads and the header flanges are nice and thick.
They are designed as a "pseudo-Tri-Y" header lacking secondary tubes! The single collector is also too small. But surprisingly the headers perform better than they have any right to do so. The system's biggest drawbacks are the mufflers which impact horsepower output above rpm.
In those days valves lifted off their seats by 0. Although that's standard valve lift for a modern street performance cam, in the early s solid flat tappet racing cams having 0.
The valve train performance of our modern street engines was achieved via advancements in successive generations of camshaft grinding machinery and it was made usable by advancements in valve spring technology. If you dramatically improve the valve train performance of your C engine, you have to assume you cannot take any short-cuts in the quality of the valve train componentry you select.
Keep in mind your engine's modern valve train may be lifting the valves off the seats as much as racing cams did 40 years ago, with less camshaft lobe duration, and with hydraulic tappets rather than solid tappets! The performance of the C 4V can be described as having good drivability, a strong dose of mid-range power, and the willingness to rev to high rpm.
As I stated previously I consider this characteristic ideal, it is something I try to avoid diminishing in any aspect when I tune the engine for higher output. The camshaft plays a major role in that. Such motors rely upon long duration camshafts and high rpm intake manifold design to widen the power band and promote mid and upper rpm power. The C 4V is just the opposite, the intake ports and valves were sized to give the motor a power band that peaks at approximately rpm and pulls strong out to rpm and in some cases even as high as rpm.
The C 4V relies upon camshaft design moderate valve event timing and intake manifold design dual plane for its lower rpm performance. The short intake duration of the factory camshafts proves a C with 4V heads does not need a lot of intake duration to have a high revving power band.
There are four common camshaft design errors that are made in regards to valve event timing that make things worse in regards to C 4V street performance: Opening the exhaust valve too late causes high rpm torque to fall-off like a brick if there is any exhaust system back-pressure mufflers.
This is one reason why I've made a note about installing the cam advanced. Too much over-lap softens low rpm torque, makes the engine idle rougher, and decreases vacuum at idle. The big intake valve and canted valve geometry of the C 4V increases the interaction between the exhaust port, the combustion chamber, piston motion, and the intake port during the overlap period. This is a good thing for a race engine, overlap can be used to scavenge exhaust gases and get the intake charge flowing early which improves volumetric efficiency.
Drivability i. While amplifying the effects of overlap is a good thing for a race engine, its a bad thing for a street engine. Small increases in overlap quickly diminish the drivability of an engine equipped with 4V cylinder heads. It is not the size of the intake port that hurts low rpm performance and drivability as people often assume, its the size of the intake valve and the manner in which it amplifies the effects of overlap.
In designing or selecting a C 4V street camshaft its important to place emphasis on minimizing overlap in order to optimize low rpm power and maintain drivability.
Narrow lobe centerlines LSA create the first two conditions. Combined they have the effect of making the torque curve power band narrower and steeper. This is an aspect people can't wrap their head around. The indoctrination enthusiasts get via magazines, internet and television makes them think they are losing out on something if they install a camshaft having wide lobe centerlines LSA.
The big 2. Closing the intake valve too late causes low rpm reversion while lowering dynamic compression. Combining the capabilities of the 4V cylinder heads, camshaft timing within the limits I've recommended, and high-lift-rate camshaft lobes max valve lift in the range of 0.
This I guarantee. If you would like my assistance in specifying a custom cam for your C street or sports car application you are welcome to contact me privately, via one of two methods: 1 Via a "private message" using the messaging capability of these forums. If you contact me via one of those two methods, I will gladly assist you. I have assisted many people over the decades since the s , and I will gladly assist you as well. But frankly, I would prefer if you asked for guidance at the beginning of your project, rather than just asking for help with the camshaft.
Pay attention to this: I offer assistance to folks who own vehicles powered by the C who wish for nothing else beyond achieving the best performance the factory C castings had to offer. I don't offer help choosing off the shelf cams, in terms of camshafts my specialty is penning custom cams for high performance street engines which perform better as street cams than any mass-produced cam available off-the-shelf. I don't offer help designing drag racing cams, I don't offer help designing cams for high output custom engines beyond bhp.
The multi-index crankshaft sprocket is an invaluable aid in properly timing a camshaft. Motor oil providing a high level of wear protection is required to prevent premature failure of flat tappet camshaft lobes, flat tappet lifter faces AND distributor drive gears. It is important to emphasize that installing a roller cam does not eliminate the need for motor oil providing a high level of wear protection; it is still needed for the distributor drive gear!
The traditional recommendation has been to select oil containing more than ppm of both zinc and phosphorous, the constituents which make the anti-wear agent known as ZDDP.
However a high level of ZDDP does not guarantee a motor oil provides a high level of wear protection. ZDDP oil additives do not help either; they reduce the wear protection properties of motor oil!
My recommendation is 10W30 Valvoline VR1 Racing Oil, either petroleum based silver bottle or synthetic black bottle ; it is reasonably priced, it is readily available and it provides a high level of wear protection. Parts should be rigid enough so that their shape does not distort. Parts should also be light, they should remain in contact with one another, and they should follow the cam's motion precisely.
There should be no unwanted motion in the valve train; such as wiggling, bouncing, surging, floating or flexing.
The properties of the moving valve train parts that work against the performance enthusiast are inertia, energy storage, flex, oscillation, resonance AND cheaply made parts! Valve train wear increases proportionally to increases in valve spring force. Increasing valve spring force shall also lower the rpm at which hydraulic tappets collapse. Weight removed from a valve or valve spring retainer is more effective than weight removed from a push rod or tappet, due to the multiplication of movement built into the rocker arm.
With a C, which has a 1. The most important characteristic for a push rod or tappet is to be completely rigid, free from flex and distortion.
Since it is less effective to lighten these parts anyway, the prevalent reasoning is to choose these parts based on strength, and to focus on lightening the valve train via the valves and retainers, where each gram of weight reduction is more effective.
A rule of thumb used in the hot rod industry says reducing the weight of these components by 1 gram will raise a motors rev limit by 25 rpm. The intake valves each weigh 31 grams more than the exhaust valves! There is a lot of performance to be gained by replacement of the "severe duty" intake valves with lighter valves such as Manley's "Race Master" intake valves grams.
Reducing the weight of the intake valves by 10 grams raises the rev limit by rpm. Adding titanium valve spring retainers for the intake valve springs is a moderately priced method for removing a few extra grams of weight, and it is complimentary to the use of light weight intake valves. Accelerated valve seat wear and valve stem or valve guide galling are problems encountered by some racing engines employing titanium valves, however keep in mind that race engines employ very high lift rate camshaft lobes and very high valve spring forces.
Race engine builders are also tempted to set the valve seats thin in order to improve air flow. Whereas Manley's Race Master valve will raise the rev limit by rpm, a Manley titanium intake valve would raise the rev limit by rpm! Cracking leads to the valve head falling off the valve stem while the motor is running, and destructive damage occurs to the motor.
People have been replacing the factory Cleveland valves with Manley severe duty stainless steel valves for decades, since the motors were new. They are a high quality, time proven substitution. Manley Performance is located in Lakewood New Jersey; their telephone number is Whatever brand of valves you choose, it is imperative the stainless steel or titanium valves you purchase have hardened steel tips.
Cast iron or beryllium-copper valve seats are complimentary to stainless steel or titanium valves. Equip the cylinder heads with silicon-bronze valve guides to best compliment stainless steel or titanium valve stems.
The valve stem to guide clearance should be set at 0. Utilize spring loaded elastomer valve stem seals such as Ford Racing Performance Parts MA50 or Manley Performance ; installation of this type of seal requires machining of the top of the valve guide to 0. Push rod deflection can cause many seemingly unrelated engine performance problems; they are the weakest link in an overhead valve type valve train.
It is important to use push rods in any application that are rigid enough for the spring forces, for the weight of the valve train components, and for the engine speeds involved. The canted valve Cleveland valve train splays the push rods off to either side of the intake port; these push rod angles expose the C push rods to angular bending forces not encountered in the valve train of in-line valve motors; the C needs a sturdier push rod.
The push rod is not the appropriate component to use for reducing valve train weight or saving money. Push rods should be manufactured from seamless chromoly tubing. The use of chromoly tubing alone will guarantee a more rigid push rod.
The larger the OD of the push rod the more rigid it shall be also, increasing the wall thickness of the tubing does not increase push rod rigidity as much as increasing the outside diameter. Push rods being specified for hydraulic tappet applications should have a 0. Of course, restricting oil to the valve train via the push rods is not a concern if a motor is equipped with tappet bore bushings having 0.
The small passage acts as a restrictor to control the amount of oil flowing to the valve train in lieu of a restrictor in the push rod's tip. Smith Brothers of Redmond Oregon and Manton Pushrods of Lake Elsinore California are shops specializing in custom made push rods. Manley Performance Products and Trend Performance are also good places to shop for push rods. There are two common warnings in using the factory rocker arms: 1 Use only steel 4V fulcrums the 2V fulcrums are made of aluminum.
There is a problem with push-rod clearance when using those rocker arms with camshafts lifting the valves 0. Sealed Power R is a recommended replacement for the factory rocker arms. Beyond those warnings the factory rocker arm has three potential weaknesses: 1 fulcrum bolt stretch, 2 push rod cup wear and 3 the quality of the valve stem contact patch a rocker arm geometry issue.
Fastening the rocker arms to the pedestals with ARP bolts 4 packs and washers 2 packs is recommended to improve the strength of the fulcrum bolts and reduce the possibility of them stretching. With the fasteners thus improved the factory rocker arm is good for up to approximately pounds over the nose and it can accommodate applications lifting the valves up to 0.
This is a high quality billet rocker arm that operates like an individual shaft mount rocker arm. This very rugged rocker arm also performs like a shaft mounted rocker arm therefore it requires no studs, guide plates or hardened push rods. Whereas billet aluminum rocker arms are good for about 10, miles, a steel rocker arm is a better choice for an engine planned for high mileage.
ROCKER ARM GEOMETRY There are six variables which impact the geometry of a rocker arm; 1 the amount of camshaft lobe lift, 2 the design of the rocker arm, 3 the height of the rocker arm's fulcrum, 4 the rocker arm's lateral distance from the valve stem, 5 the height of the valve stem and 6 the length of the push rod.
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