What is the difference between ARP 625 and ARP 2000 bolts?
The tried, true, and very popular ARP 2000 material is a quench and tempered heavily alloyed martensitic steel with a typical 44-47 C- scale Rockwell hardness and rated at 220,000 psi tensile strength.
The ARP Custom age 625 + counterparts are comprised of a higher tensile strength super-alloy corrosion resistant material, also quench and temper heat treated, to a robust 260,000psi. These higher rated bolts are offered as an optional upgrade from our basic 2000 series provided in all Pauter rods.
Can I order a single replacement rod?
Single rods are available. The information necessary to match the rod weights (reciprocating and overall) of your existing set was in the box printed on a yellow card. If the information is not available, and you purchased the rods directly from us, we should have your rod weights and sizes on file. Contact us for more information..
What is the difference between a forged and billet steel connecting rod?
Forging is a preformed, closely shaped, individual part, whereas a billet is typically formed from a flat rolled bar stock. Forging is designed to take full advantage of manipulation of grain structure throughout the shape of the finished part. Billet processing in rod manufacturing, on the other hand, is the complete machining of a rectangular block of material resulting in a finished part. Our manufacturing methods combine the strength of forging and the consistency of billet steel.
Can I run my rods without a pin end bushing or can the pins be press fit?
Bushings are preferred for ease of assembly and reparability. Typically, we hold our fit to what we consider to be the bottom side of clearance (.0005″ to .0006″ target), since it’s far easier to open the bore than it is to close it. If requested we can hold size to suit specific values noted at time of order.
What bearing clearances do I run with these connecting rods?
This depends greatly on the application, however .0010″/.0015″ per diameter inch is a commonly considered operating clearance standard. Stacked tolerance—the combined tolerances of crankshaft journal, bearing, and rod—of all corresponding parts plays a big role in determining the final clearance. Applying perceived dimensions from specification manuals will rarely match sizes needed to determine true physical clearance, for this reason we recommend actual rod and main bearing clearances be established though the use of dedicated equipment such as micrometers and bore gauges we also suggest contacting your engine builder or our tech department for a personalized recommendation on your specific engine program.
We are sometimes called upon to set specific rod bearing clearances when supplying rods to clients. This procedure is offered as an optional service and only when absolute crankshaft sizes (.xxxx”) are known and bearings to be used are supplied. For more on this, contact our tech department.
What side clearances do I run with these connecting rods?
Favorable side clearance values for crank guided applications are .010”-.012” with a minimum recommendation of .008” per rod. This value should be doubled in shared journal engines (as in most “V” configurations). In assemblies where minimum clearance is to be maintained, groove thrusts should be considered.
How much do your connecting rods stretch?
What is often referred to as rod stretch is actually a result of flex of corresponding parts combined with movement allowed by necessary operating clearances involved within the assembly as well as thermal expansion inherent in the internal combustion engine. Truth is any true physical rod stretch would likely be from deformation of the big and/or small end bores which could in turn lead to serious engine damage. In short, actual steel rod stretch itself should be near zero with exception of thermal expansion but all aspects mentioned above need to be considered during engine planning / assembly stages with regard to rotating and deck clearance minimum requirements.
Can a connecting rod be rebuilt?
Pauter, like most aftermarket rods are manufactured in a way that lends itself to rebuild provided any damage is within accepted repairable means. Contact us prior to shipping parts for repair
How do separate rod and cap?
Conventional bolt layout: Unscrew the bolts about a quarter of an inch. Then, holding the cap, tap lightly on the screw heads with a non-marring hammer until the alignment sleeve is clear of opposite face.
Porsche/VW bolt layout: Unscrew the bolts about a quarter of an inch. Then, while holding the beam, tap lightly on the screw heads with a non-marring hammer until the alignment sleeve is clear of opposite face.
Doesn’t the roller tip make the rocker less durable?
The simple answer to this is no, and the reasons are slightly more complicated. Generally the only way a rocker wears down is via the corresponding contact surfaces, which will experience many hundreds of millions of cycles in just a hundred race hours. Focusing maximum load on the valve tip or lash, this single point becomes the most likely candidate as a point of failure. Replacing this single point of contact with our roller tip provides over 1.7 inches of rotating case hardened tool steel, which can increase the lifespan of a roller tip exponentially.
What follow-up procedures are recommended after rocker installation?
Beyond retorquing stands and rechecking the valves after cool down, there are no break-in procedures for these rockers.
How far out (how many revolutions) can the adjuster screw protrude from the rocker body?
No more than three screw revolutions should be used to ensure proper thrust distribution. If more than three screw revolutions are needed for proper connection, it is likely the pushrod length is incorrect.
How much do I torque the adjuster screws?
Adjuster screws should be hand tightened as it is only necessary to lock its correct setting position. This is accomplished using the appropriate size box type wrench.
How much clearance should there be between the rocker side and thrust washers?
We recommend .010″-.020″ clearance for proper oil flow/lubrication.
Can I add shims between the rocker stand and head if the pushrod does not sit properly in the screw cup?
Shims should only be used to optimize proper geometry with regard to rocker and valve tip. Only after following that procedure can a proper pushrod-to-adjuster cup relationship be determined.
If I’m concerned about over-springing my cam or rocker arm, should I reduce the spring pressure as a safety precaution?
Applying inadequate spring pressure has significant adverse impact on the life of a rocker assembly as well as valve and valve spring. Engines are designed to operate within certain pressure constraints. Depending on cam profile and Engine rpm, insufficient spring pressure can actually cause loss of valve control, which may turn a properly controlled lift-and-lower operating cycle into a destructive jackhammering motion. If you are uncertain, please contact a qualified valve train tech to ensure proper spring pressure is included in your particular engine program.
I keep breaking rockers, should I purchase rockers composed of heavier duty material?
The pressures and load applied to either side of a rocker, if adequate, are not so significant that they should cause a fracture. A broken rocker, while not good news, should be seen as a warning sign providing you the opportunity to find the cause. It is for this reason that simply replacing a broken rocker with a new unit could very likely result in catastrophic damage to a number of corresponding engine components (valve, piston, head, block, etc).
Can I replace just one rocker?
Rockers function in tandem, each one ostensibly experiencing the same wear and level of fatigue. If one unit is fractured, it is likely others may fail as well. Though it is feasible to replace a single rocker arm, the possibility of future failures remain.
What causes rockers to break (and how are these things prevented)?
Float – Loss of control of the valve train.
Prevention: Coordinating proper lift rates, spring tension, component weights, and RPM.
Coil bind – Exceeding usable travel of the spring as installed.
Prevention: Ensure proper spring/valve travel prior to bind.
Retainer and guide collision – Inadequate retainer to guide clearance.
Prevention: clearance issue at this point must be detected and corrected during initial setup of the heads.
Prevention: Must be considered and corrected if necessary during the planning and pre-assembly stages of the engine (re)build.
Continue to Rocker Info.