Bilster

iTrader: (21)

I need to know what modifications are necessary to use Gen I rods in an LS build. I have an expensive, nice set of 6.25" long Crower titanium rods that I was going to use in a Gen I build but got pulled into the allure of building LS motors and have really never looked back. Because of the rod length is unusual, I'm not going to get my money out of them so I might as well look into the modifications that will make them usable for me. Can anyone detail these mods?

XtraCajunSS

iTrader: (2)

You'll need a piston with a custom compression height dependant upon your choice of stroke. Do you know what bore and stroke you are going for? The piston may be a shelf stock part for some manufacturers.

Shane

Bilster

iTrader: (21)

Shane,

I am aware of the piston compression height. I did actually find an off the shelf unit that will work. I've got an LS6 and will be using the stock stroke along with the 6.25" rods. I need a compression height of 1.179. Probe has a piston for a 3.900" stroke and a 6.125" rod. It's part number is 14228-PS-C373. It shares the compression height that I need.

My question is actually based on the modifications needed for the rod itself. There is something to do with correcting the off-set of the SBC rod and the fact that SBC rods are chamfered at the big end and apparently LS rods are not. It's these type of issues that I'm questioning.

Oldsmobility85

iTrader: (1)

Im not completely positive but aren't conventional small block rod journals (2.100in) larger than ls rod journals? That means you would have to use a thicker bearing or custom crankshaft.

I was reading in engine masters about Robin Lawrance's LSX build for that nova and he was originally having problems with scalloping of the bearings due to crankshaft deflection. To correct the problem he dropped the stroke down and brought the motor from a 454 to a 434 inch motor and had a custom crankshaft built that utilized small chevy 2.100 rod journals for added strength.

Anyhow maybe that will give you something to look into. As far as the chamfering goes a chamfered rod can go on a non chamfered crankshaft but not vice versa. But the bearing itself is what you have to worry about most. P series bearings are for normal stock style crankshafts and H bearings are for your better aftermarket style cranks utilizing .125 fillets for added strength.

Taspeed

iTrader: (1)

you can see my post in the gen III forum

XtraCajunSS

iTrader: (2)

There are no modifications necessary. The rods interchange. The only difference is the offset. LS1 rods are "on-center" whereas SBC rods have an offset between the big end and little end. Back before LS1 rods were common, I build many, many LS engines with 6.125 SBC rods. FWIW, the connecting rod bearings for LS and SBC are the same part.

Shane

JAX04

iTrader: (17)

so is there any reason why one would choose the LS rods over the SBC then?? Does that offset make the rod weaker?? If it does, does it even matter, say, below 1000 whp??

NemeSS

iTrader: (127)

ive used sbc rods in ls engines before as well. no biggie. i will be using them in my next build. as matter of fact. with custom compression height pistons.
and bore.

Oldsmobility85

iTrader: (1)

That's great info. thanks for your post.