I had the rod journals ground down and new cleavite bearings installed(due to spun rod bearing). Now this was a Fully built Cobb block that had previously had its crank balanced and everything...

do you think its necessary to have the crank rebalanced? I probably won't be spinning it up anymore than 8,500 at the MOST.

You've removed weight from the crank so I would have it rebalanced.

gosh 8500 thats mighty high, your looking for problems taking it that high

You should take .010 off the mains also. Its not necessary but i'd do it. And the crank will definatly need to be balanced. The machine shop will balance it when its turned anyway.


And i'm not too sure about the 8500 rpm redline either.

You should always rebalance the crank anytime you break into the block.

The way our flat four crankbalance works, you really don't chance crank balance as long as you take same amount of weight off from both sides of
the crank (in this case you do). We still put cranks in balancer every time just to make sure, but you will not see much difference. Flat 4 crank is almost perfectly balanced when you change weight (rods,pistons,rings,bearings and journal diameter) as long as you keep the weight of the components the same on both sides. Only inlane 6 and flat 6 are better.

The way our flat four crankbalance works, you really don't chance crank balance as long as you take same amount of weight off from both sides of
the crank ...

thats what the guy told me. ALso they don't have a crank balancer in house... Should I push him to get it balanced? How much off could it possibly be if they remove the exact same amount from both sides? could I possibly see any problems down the road? even if max redline is 8k?

Re-balancing the crankshaft would only be correct, honestly it is not worth guessing and or taking a chance. The crankshaft needs to be balanced.

- J

I agree, it will give you peace of mind.

ok u talked me into it... Just got off the phone with him. for only 125 bucks I guess it really is worth it for peace of mind like u said :)

it would also be smart to get the block line honed to make sure that the crank bearings sit perfect in relation to one another.....it's amazing how bad the subaru block's are.....at least the ones we've measured up.............some more piece of mind :)

I think I could spend money all day on the thing...balancing the crank is prolly the last dollar I want to spend on her for right now.... Just spent about 5500 bucks JUST on the block alone....:alien:

heads are another story... heh

Right now I just want my motor DONE so I can finish it by Spring time ! :cool:

Cool, let us know how everything turns out.

Hmmm...how high were you spinning it before the bearing spun?

I didn't spin the bearings.... Bought the entire cobb block WICKID cheap with just the spin rod bearing.....little did I know it scraped the **** out of the cylinder wall too. Then I had to sleeve it ;) Almost a year later, my engine is almost done...and I actualy have the money to pay for it !

Ahh, I remember now. Yep, "used and damaged" is a very tricky purchase, but I'm glad to hear you're getting close.