"Mixing and matching", cast & forged on the small block

Couple of questions. I think we all know a cast harmonic balancer on a forged crank, (and viseversa) is a no-no, but what about using the later (72-73) 340 connecting rods on a steel crank? According to "the book" these rods are shown for a cast crank, do you get in trouble using them in a steel crank motor? And, woud a cast crank 318 balancer work on a cast crank 340? This is a basic street motor, not race. Thanks in advance for th eknowledge.

"IF YOU'RE UNDER CONTROL, YOU AIN'T GOING FAST ENOUGH."

I have used these parts dampers, rods (not the old skinny ones) and cranks (273 forged) with no issues in a 318 project with forged pistons. As far as I know the 340 forged crank is same forging, but the crankpins are drilled through to lighten them for correct balance with a neutral damper (same as 318) and the heavier 340 pistons. The cast 340 crank has an offset damper to compensate for the lighter crank material. I think you can mix 273/318 parts with no big issue, if using the 273 crank with 340 pistons I would say use the offset damper (And converter!) My Forgot to mention: Stay away from the 360 damper/converter for the 340 parts! There is way too much offset material on the 360, for 360 use only.

318's all have a neutral balance cast or forged. There are only two basic factory connecting rods. Small (318,273) and large (340,360) in the later years they changed to press pin and I think they eventually started using large rods in all the motors. I would not use a 340 cast crank to help balance a rotating assembly because they are not that common and you will have a hard time if you want to use an after market damper in the future. I think you wont need to add weight to your crank because new parts are lighter. An FYI wiseco/ K1 has a clearance on H beam rods for real cheap they are lighter stronger etc. You probably can't rebuild factory rods for the price that they are selling them for.

littleval : you have a .com address for that clearance sale? Thanks, Dave

http://www.wiseco.com/ Go to the Clearance on the right side and open up the K1 clearance page. A matched set of rods is $219 for h beams you just can't beat it. I bought some 6.250 chevy rods for the same price they where not a matched set but they still ended up being close enough.

if you already have the parts they should work fine. the 340 rods were a good piece, fine for mild builds.

however... sounds like you have a forged steel crank and are basing your build around that. if it needs machine work then balancing then you have to find matching parts etc spending a bunch of dollars... you REALLY should reconsider and look at muscle motors or someone for a 408 forged crank stroker kit. they COME WITH the rods and new pistons and a new forged crank and will get you a lot more power. yes you will still need to have it balanced and checked for all tolerances, but the money you save piecing the 340 together is not worth it.

looks like $3899 total for the forged short block already, balanced, from muscle motors. just a kit would be cheaper.

how much will you save doing the 340? after adding all the parts up and machine costs?

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408” in a 360 race prepped block with Bracket rotating assembly $3899

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