Do connecting rods stretch?

Do connecting rods stretch?

Connecting rods are exposed to both compression and tension – compressive force as it travels to top dead center and tensile force as it travels down the bore. I believe they stretch because the rods are weaker in tension than they are in compression.

How much do connecting rods stretch?

All told, it’s about . 004- to . 006 inches of stretch — about as thick as a piece of paper. “That’s extremely important to making sure that the friction between the bolts, the lubrication and the rod itself is consistent with the testing that we’ve done,” Stothers said.

What are rod bolts?

Connecting rod bolts are the securing link between the piston assembly and the crankshaft. The rod bolts, because of the need for great strength, are generally made of heat-treated ahoy steel. Fine threads with close pitch are used to give maximum strength and to permit secure tighting.

Can you run aluminum rods on the street?

Yes you can run them on the street but they will fail. Aluminum rods have a definite metal fatigue life and when that’s reached they are going to come apart.

What happens if you over torque rod bolts?

Over-torqued or over-tightened bearings cause the rod end cap to bow in the center, resulting in an out-of-round profile.

How hot does a connecting rod get?

The correct method of fitting piston pins to this type of assembly is to heat the small end of the connecting rod to 250°/300°C, ideally by using one of the proprietary devices manufactured especially for this type of piston pin anchorage.

Are longer connecting rods better?

Longer rods can improve rod stroke ratio, reducing thrust loading on the piston. Many racing engines use longer connecting rods to help reduce piston weight while having positive effects on torque curve shape and positioning and combustion efficiency. Longer rods typically require shorter, lighter pistons.

Do you put Loctite on rod bolts?

It is the PRELOAD and only the preload that prevents fatigue cycles and fractures on something like a rod bolt. Loctite is good for non-rigid connections, like soft gasketed joints. I use it between the rod/main bearings and the rod/block to help avoid spun bearings–along with the bearing crush on the high side.

Which way do connecting rods face?

“When assembled, the flanges on the connecting rod and cap should face to the front in the left bank and to the rear in the right bank. Install the piston with the stamped arrow facing forward.”

Why use longer rods?

How long do titanium connecting rods last?

Titanium Connecting Rods That comes with a price; titanium rods typically are typically four times the cost of a billet steel rod. The other drawback is that titanium rods do have a fatigue life in race applications and are typically switched out every 40-80 hours.

How do you stretch a hot rod rod?

Tighten one bolt to the manufacturers recommended torque and measure the stretch. If necessary increase torque until you reach the recommended stretch. Once the bolt is stretched to the recommended spec, loosen the opposing bolt and retighten carefully until the recommended stretch is achieved.

How to make an ARP rod stretch gauge?

1 Install the rod cap and insert the rod bolts with the recommended lube on the bolt threads and the bolt seating surface. 2 Use a nut driver or the appropriate ratchet and socket to snug the bolts and gently seat the rod cap. 3 Loosen both bolts to ensure there is no preload.

How much torque do you use to stretch a rod?

The difficulty with the application of torque is there are multiple variables that can affect how much of the applied torque is used to overcome friction and how much actually stretches the bolt. The overwhelming majority of applied torque (around 75- to 80-percent) on a bolt is actually used just to overcome friction.

What’s the best way to tighten rod bolts?

Two methods are commonly used to tighten rod bolts and rod bolt nuts, but only one excels for application to racing and high performance engine assembly. Among these, tightening a bolt or nut to the recommended rod bolt stretch factor is the preferred method for all racing and high performance engines.