caddi1

Okay I have been trying to figure out what pistons to go with (stock) but every time I find something and try to price match stuff, different bore sizes pop up. Rod length will be the same 6.125" and stroke will be the same 3.622" but for some reason I keep coming across different bore sizes and I have no idea which one is the right one. some places give me the option for 3.905" and others show 3.898" I'm just super confused and it might be something simple I'm over looking but I am so ready to order pistons anyone who can help will get a gold star from me! Thanks guys

redbird555

iTrader: (14)

Stock bore for ls1/6 is 3.898 the 3.905 will be for a .005 over piston which is about as big as you can go on a stock block

2000PewterT/A

Pistons also come in 3.903 bore, but by far the most popular bore size if the vehicle is getting bored is a 3.905

caddi1

okay so what is the difference between 6.125" rods and 6.098" rods? Stock is 6.098" for rod length and bore size is 3.898". Does stock bore pistons work with 6.125 rods? I have 6.125" rods and I am trying to figure out what to attach to them.

redbird555

iTrader: (14)

No it won't work the stock gm ls1 pistons have the wrist pin low to accomodate the shorter rod.To run those rods you would need an aftermarket piston setup for a 6.125 rod. Stock gm pistons are made for stock rod length. You need an aftermarket piston made for whatever bore your running (3.898 or 3.905) with a wrist pin height setup for a 6.125 rod

BlueBird346

iTrader: (13)

Stock bore is 3.898. Bore as little as possible, do stock or 3.903 if you can get away with it. Pistons and rods need to match each other. If your going to use 6.125 rods make sure the pistons specific to that rod length.

redbird555

iTrader: (14)

I would go with 3.905. Reason being is that the op is gonna need a bore it sounds like anyway and .005 is perfectly reasonable to go to on a stock block the 99-02 ones can even take a .010 bore. Depending on the mileage the bores may have a slight egg shape to them. I'd just go 3.905 and call it done. 3.903 is just a hone

KCS

iTrader: (20)

Depends on the pistons. Most aftermarket pistons and rods use a .927" pin when the stock rods and pistons use a .944" pin. Of course, some 6.125" rods and aftermarket pistons are available for a .944" pin.

This is just a pet peeve of mine, but there is a difference between boring and honing. Boring is the process used when cutting out a lot of material. Honing is used to get a specific surface finish and is typically done when there is just a little bit of material left to remove before the bore is finished to size. Going from a 3.898" bore to a 3.905" isn't going to need to be bored.

With that said, if it's getting torque plate honed, 3.905" is nicer because it gives the operator a little more material to remove when the torque plate is bolted on and the bore is distorted. 3.903" is usually fine, but it is close. If it's a high mileage block I would shoot for the 3.905" piston.

redbird555

iTrader: (14)

This is true my mistake. I'm just used to using the terms interchangabley. A bore usually takes off .010 or bore and actually "cuts" the cylinder whereas a home uses a stone and knocks off less material in the same manner