Engine Rebuilding-Automotive Machine Shop-High Performance & Hot Rod
Connecting Rod Reconditioning
Connecting Rod Reconditioning Process Step by Step
1. Check the parallelism, alignment and the roundness of the connecting rods.
2. Replace or recondition the unaligned or bent connecting rods.
3. Replace all the connecting rod bearings.
4. Inspect rod bolts for stretching and thread damage. If in doubt, replace the rod bolts. This should be done before the connecting rod is resized because some bolts are pressed into the rod and will cause distortion that will be corrected during the resizing process
Then resize on the Sunnen Hone.
The big (crankshaft) end of the rod is then measured with a special dial bore gauge that is attached to the rod hone.
A connecting rod that originally used press-fit wrist pins can be honed and equipped with a bronze bushing to accept full-floating pins, which are common in performance aftermarket racing pistons. The rod hone is used to size the small end of the rod to accept the bushing. Floating pins reduce both internal engine friction and reduce the natural twisting and bending loads experienced during combustion.
The connecting rod of an engine is one of the most abused and least respected parts. The load and stress it experiences are extreme. For example, the connecting rod must support four to five tons of pressure during combustion. Also, the rod is required to reverse its travel many times a second. As an example, a connecting rod in the average engine running at 3,000 rpm is reversed 100 times in one second. Much of this load is applied to the bolts that hold the rod to the journal. For this reason, new high-quality connecting rod bolts should be installed during any performance rebuild. The first step is to press out the old bolts, as seen in this photo.
Engine Rebuilding-Automotive Machine Shop-High Performance & Hot Rod Engines
475 West Street Walpole MA 02081 Phone : 508-734-0053 or 508 668 4784
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Engine Connecting Rod Reconditioning
The connecting rod plays a vital role in the engine. But a connecting rod is under tremendous stress, with the weight of the piston sitting on top, changing direction thousands of times per minute. This continuous stopping and changing of direction combined with the weight of the piston and speed of the engine hammer on the bearings and torture the rod bolts which hold everything together.
Proper geometrical alignment and bearing surfaces that are smooth and perfectly round is the best way to ensure long engine life.