Hello I have a vortec 350 880 block with matching heads. I got it from a friend who said it ran when pulled but regardless I am rebuilding it since I don't know the exact history. I haven't pulled it apart all the way yet but I was thinking about piston pins. When should those be replaced? What clearences should be checked if any? What's good and what's bad when looking at them with the pistons and rod assembly out of the engine? I'm asking just because I've never really heard of people worrying about replacing these often when doing a simple rebuild as I am but I want to check while it's apart and have some knowledge about them. Thank you
74c20
Piston pin wear check and possible re use
Piston pins are a press fit in the connecting rod. They are not replaceable unless the entire piston is being replaced because the piston usually does not survive removal of the pin.
It is possible to modify the rod to accept a floating pin that is serviceable but this for the factory rod is a precision job done in a qualified shop and usually is accompanied with a Casidium coated pin for proper wear properties in a stock rod which doesn’t have enough material thickness to safely be bored for a bronze pin bushing.
Given the problems that early GM powder forged rods had not only on the street but most certainly in high performance engines it is pretty typical to replace them with aftermarket 5140 or 4340 alloy forged rods that are designed for floating pins. This allows at home or in the pits piston and or rod replacement without the needed of a press and some alignment tools and a rod flame heater or a block of dry ice for reassembly of pin to rod.
The 880 block was used in 1995 under Swirl Port heads their typical last three casting number digits are 191 or 193. These are not performance heads and cannot be ported to make them into such as the swirl vane cannot be satisfactorily removed, they are, however, great grunt heads for a working truck. Starting in 1996 the 880 block appears with L31 Vortec heads the last three casting number digits are usually 062 or 906. These are the wonder heads of high performance builds. So you need to be explicit as to the year of the 880 block and the head casting numbers. A quick way to tell from the outside is the Swirl Port heads use a six bolt intake pattern similar to the 55-86 standard SBC pattern where the 96 and up L31 Vortec heads use a 4 bolt intake pattern.
Bogie
It is possible to modify the rod to accept a floating pin that is serviceable but this for the factory rod is a precision job done in a qualified shop and usually is accompanied with a Casidium coated pin for proper wear properties in a stock rod which doesn’t have enough material thickness to safely be bored for a bronze pin bushing.
Given the problems that early GM powder forged rods had not only on the street but most certainly in high performance engines it is pretty typical to replace them with aftermarket 5140 or 4340 alloy forged rods that are designed for floating pins. This allows at home or in the pits piston and or rod replacement without the needed of a press and some alignment tools and a rod flame heater or a block of dry ice for reassembly of pin to rod.
The 880 block was used in 1995 under Swirl Port heads their typical last three casting number digits are 191 or 193. These are not performance heads and cannot be ported to make them into such as the swirl vane cannot be satisfactorily removed, they are, however, great grunt heads for a working truck. Starting in 1996 the 880 block appears with L31 Vortec heads the last three casting number digits are usually 062 or 906. These are the wonder heads of high performance builds. So you need to be explicit as to the year of the 880 block and the head casting numbers. A quick way to tell from the outside is the Swirl Port heads use a six bolt intake pattern similar to the 55-86 standard SBC pattern where the 96 and up L31 Vortec heads use a 4 bolt intake pattern.
Bogie
What he said.
pistons are worn out before the pins are and piston sets come with new pins so not generally a concern.
In some racing sanctions where super light weight everything has an advantage it's possible to use an ultra weight thin walled pin weighing in a half the stock would. Those you have to keep and eye on and R@R as needed.
That's not what you asked though.
pistons are worn out before the pins are and piston sets come with new pins so not generally a concern.
In some racing sanctions where super light weight everything has an advantage it's possible to use an ultra weight thin walled pin weighing in a half the stock would. Those you have to keep and eye on and R@R as needed.
That's not what you asked though.
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