I put together this chart of our common engines, maybe Titen can make this a Sticky since it is becoming more and more common for guys to need to know these specs for parts swapping and interchanging components from other engines.

Nice! And thanks for this.
Can you post the specs on the 5.7 LS series engine pistons also?
I thought they are close, but can't remember off hand.

MBHD

Yeah sure, i'll have to do it when I get home tonight/this morning!

Here is a piston swap alternative for the 250 using aftermarket 6.00" rods and 5.7L LS Chevy V8 pistons.

That one will leave the pistons .040 or more down the bore.


Also , the 181 uses a 5.7 rod.

Yeah, its about .010" more than the stock 250 piston and rod. Many want to use this swap because it gives them a cheap set of long rod pistons and they don't have to buy custom ones for $600 bucks or more. They can spend that extra to deck the block more or other pieces and still be out on the cheap side. The LS guys will give you a set of their take outs and you'll only have to buy the rods and do a little pin fitting and your good to go.

I thought the 181 were 5.7" but didn't have any real data to back it up before I made the chart, and then the edit button went away too soon again.

Thanks

MBHD

You welcome Hank. This will give guys another option to building a budget long rod 250 engine. The factory LS pistons are hypereutectic and the same quality that are used in the new Vettes and Camaros that make over 400 HP. There are always people looking for different alternatives, and this can help. Even the forged LS pistons are cheaper than a forged piston for the 250's because of popularity and demand, so that is also another option to explore if your considering buying some aftermarket rods for your project.

Correct me if I am wrong but don't V8 pistons have a slight offset pin to accommodate the left and right banks when installed. If so how would you install them in a straight up in a 6 cylinder. I think you would place the offsets all in one direction and installing #5 & #6 opposite from the other 4 if you happen to get a set of 8 LS pistons.

All factory pistons have offset wrist pins, even inline engines. V8 pistons are not specific left or right unless they have valve reliefs for the intake and exhaust valve that makes it so, even the (4)valve relief stock V8 pistons can be either a left or right. A true flattop with no valve reliefs can be a left or right also depending on how you put it on the rod and in the engine. So you actually can have (8)lefts of rights that way.

I was looking at the SCAT web site and the 6" rod has a pin end dia of 0.927". The stock LS1 rod is 0.943" dia. I don't think that combination will work. All stock LS1 pistons I looked at do not have a 0.927 pin dia. All have 0.942" ins dia. I thought why not use the whole LS1 rod/piston combination. Looking further I found Lunati makes a rod bearing set (PN CR867HP) that will space a 2.10" rod to fit the 2.00" small journal. Also the LS1 rod is 6.098" long and the 4.8 lit LS rod is 6.278" long due to the shorter stroke. If the longer rod is used would it address T Lowes comment about the piston being lower in the block. This is a paper investigation as I have no real hardware to see if this is feasible. I find this approach very interesting. Any thoughts appreciated on this.

Well isn't the 5.7/350 a 4in bore??? the last I knew it was. so for most this will be .100 over bore. Or did I miss something in all this??

Were talking LS series engines .

MBHD

I am laying in the weeds on this build also. I am nearing the end of my setup now (307 pistons) and have a good std. block. This sounds just down my alley...

The problem with V- engine rods are #1. They are offset and #2. The bottom end is narrower. As far as I can tell the off set is a result of the narrowing of one side of the big end so the V rods can set side by side on a single crank pin. They use the same bearing so I don't know what the "actual" effect would be. I know what some say it would be.

Scott, The 181 rod length is also 5.7" But the big end uses a 2.1 bearing.

Larry, the 5.7L LS engine replaced the traditional 350 style engines in 1997. The SBC engine we all knew during the 60's, 70's and so forth died in '97 and is no longer made. The LS is still 5.7L, but is 3.897" bore with a 3.62" stroke. So its been the standard Chevy V8 for almost 17 years now, so I guess you could say that you kinda' have missed something.

The wrist pin issue can easily be corrected by honing the rods S/E to fit the LS pins. In a perfect world, the pistons would work out to give you a near zero deck, but when you try to swap non-standard components around, you may have to cut and trim parts to make it work to suit your needs better. But then again, this is a budget rod and piston swap that will cost about the same for a set of H-beam rods and pistons together as just a set of forged pistons for the 250 by themself.

Using the LS specific rod and piston will require you to cut the piston top because it will stick up out of the block and also require a spacer bearing for the rod journals, plus they are already too narrow for the 250 crankshaft.

So your saying a 350sb is no longer a 4in.bore hum who would have thought. I guess it has been to long, Not playing with them Vthings LOL.

Yeah, its slightly undersize now at 346 cubic inch, but they still call it 5.7L . The blocks are crossbolt main style like the 426 Hemi, as well as 4 bolt main and also aluminum from the fatory, and they are getting crazy insane HP out of these engines with turbos and blowers today. The heads look like a smaller version of the Big Block Chevy with the intake port spacing and are pretty impressive. Its just amazing how far the technology has advanced since these engines were introduced.