lz4 (3.5 vvt) crankshaft specs

[sharkey]

im looking for some specs on the lz4 crankshaft, such as main journal diameter and width. essentially what im trying to do is drop it in an older block. all ive been able to come up with is its a 3" stroke and its steel.

[Guest]

Won't fit into the older blocks without notching of the block.

The mains are the same size but the rod journals are bigger. Because of this the rod will hit the side of the block if it is not notched.

The lz blocks have notches where the rod throws come close to the block in the oil pan vicinity.

However now that I think about it the lx9 crank has thr larger rod diameter too and not sure if that block is notched. You could prob use the lz4 crank in the lx9. Older block like 3400 or 3100 will prob need notching

[sharkey]

are the rod journals 2.25" like the 3900? ive read about rod clearance being an issue with a 3900 crank in a 3400, but would it still be an issue with the shorter 3" stroke vs the 3.3" stroke. my other thought would be to grind the crank down to 2.200" for small block rods, or 2.000" for early sbc style rods.

right now i have a large main gen 1 block that needs no machining. for what im planning to build it would be nice to have a steel crank, however i need to stick with the smaller bore sizes as i have to stay under 183 cubic inch

[Guest]

I'm pretty sure that an LZ4 crank would work fine in an older block, probably even without notching of the block. I have an LZ4 on a stand right now (blown up, dropped a valve and destroyed a piston and one head). I can place an 1/8" flat stock piece between the rod bolt head and the block's pan rail with a bit of clearance left over. The pan rail on a 3100 to 3500 (LX9) should be in a very similar, if not the same position in relation to crank center line. LX9 block has some small notches already (due the larger rod journals), for piece of mind you could grind some notches into the block if it's closer than about 1/16".


LZ4RodtoPanRail01.jpg

LZ4RodtoPanRail02.jpg

[sharkey]

thats exactly what i needed to know. now i gotta keep an eye out at my junkyard for a vvt 3500 i can steal the crank out of

[Guest]

If I get the crank out of the LZ9 and get my 3100 block together, I'll try to slide the crankshaft into the block and see how much clearance there really is, but I think it's pretty promising.

[sharkey]

looking at a few pics it looks like the lz4 and lz9, id assume both engine use the same block and the notches are there for the larger 3.3" stroke crank. i doubt gm made the pan rail wider on these engines, doesnt make a lot of sense to make the pan rail wider and still notch it for the rods.

if you get a chance to test fit that would be great. i can get a crankshaft at my local pick and pull for $40, but i dont want to pull one out of an engine unless i stumble across an engine lying on the ground, or a car thats had the trans removed already.