GoatChs

iTrader: (8)

I recently purchased a new high end forged crankshaft for my 408 project. Received a call yesterday from the machine shop stating that the crank is extremely out of balance with 325 grams at the snout and 275 grams at the rear flange. I have absolutely zero experience in this, and I do trust the machine shop is providing correct info.

Is this within "typical" for a crankshaft to require this much weight for balancing? To me, it sounds like an out of spec factory second that was passed along.

REAL INSIGHT is appreciated greatly.

Note: I have intentionally left out the name of the sponsor where purchased and crank brand to avoid turn this thread into a "bashfest".

MAC4264

That is a lot to be out of balance. I know you want to keep the names disclosed but here is some insight. Eagle and Callies I know for a fact rough balance there cranks to 1800 bobweight. This can be accomplished with standard parts such as most off the shelf pistons and h-beam rods. If your going with super light componets then this could be true or the complete opposite with very heavy parts. Ask your shop to tell you the bobweight. I just balance a stock crank with Wiseco pistons, light weight I-beam rods and the weight was 1692. Which for a street motor with steel rods is light and that crank was less than 100 grams on both ends. If the crank is another brand it may have never been rough balance and it could be that far out. The only other thing you can check is to see is if the shop that is balancing the crank for you knows that it is neutral balance on both ends. It is not external on one end (weight on flywheel) and neutral on the other like a LT1.

GoatChs

iTrader: (8)

It is another brand that you don't see alot of here on the forum, and you're correct, these cranks are not delivered with even a rough balance--they'll do it but it is extra. I will check with my machinist on the bob weight and neutral balance. We are using Lunati pro-billet rods & Diamond 4.030” bore x 4.000 stroke, -15.0cc, off the shelf pistons.

I appreciate your response. Thanks.

Ferocity02

iTrader: (60)

What shop did you go with to build your motor? I am still looking for some ones to build my 427. Thanks

Lasershop

iTrader: (2)

Who is doing the machine work in the bay? Just curious. Do they do in house or send it out?

GoatChs

iTrader: (8)

I'm having the entire project done at Rob's Auto Machine/Custom Dyno Tuning in Hayward, Ca. I don't have any previous experience with either but have worked with others in the area and am still trying to find one that does the work right at the price they quote.

Rob's Auto Machine in Hayward is doing the machine & assembly, but they send out the crankshaft balance work...don't know the name of that shop but I do know that he just bought all of Cola Crankshafts machines when they went out of business, so they definitely have appropriate equipment. Results are pending.