One Step Forward, One Step Back

If you recall, work stopped on the 383 due to push rod length issues. Because of different valve stem lengths we had to use non stock length push rods. We had ordered them over a year ago, but never really got around to checking how well they worked.  The basis for all this is they fact that we were using roller tip rocker arms. An oft overlooked part of engine building is checking where the roller tip contacts the valve stem over the duration of the cam’s lift. When using standard stamped rocker arms this is really a non-issue. The large radius of the contact pad is very forgiving of push rod length issue. However roller tip rockers have a very narrow contact patch. While this reduce horsepower robbing friction, it also puts enormous pressure on a very small area of the valve stem. If this contact patch does not fall on the correct part of the valve stem it can lead to mushrooming (deforming) of the valve stem tip. This picture from Comp Cams illustrates the proper location of the contact patch at various points of a cam’s lift.

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The Long and Twisted Tale of a 383

This engine has been a long time in the making. I believe talk of building this engine began around 2002-2003. We had a spare 4 bolt main block out of truck that had massive oil consumption issues due to broken piston rings and bad valve stem seals. Being that it was a 4 bolt main block, we wanted to build something a little more special than a run of the mill 350. We decided a 383 would be a fun engine to build and we began to gather parts. It took almost all of 2004 to get the parts together and have all the machining done. The block was boiled, then painted with Chevy orange on the outside and Glyptal  in the lifter valley.  Glyptal is a paint that is normally used to coat the windings in an electric motor, however engine builders use it to make the oil flow down the lifter valley quicker. A local machine shop bored and honed the cylinders, and line honed the mains.  By December 2004 we had all the parts we needed and were ready to assembly it. We added the heads and a partial valve train around 2006 and it has sat in silence since then. Below are some of the details of the assembly of the short block.

It’s based on a 4 bolt main truck block that was pulled from a 3/4 ton ’86 pick up. The rotating assembly consists of an Eagle 5140 steel crankshaft, Eagle H-beam rods, and Speed  Pro hypereutectic pistons. The Block was bored, honed and painted. The mains were line honed with an ARP main stud kit installed. The bottom end is very stout, and should handle pretty much any cam/head combo we could dream of.

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The bare block with bearing halves installed

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