Hello,
I just purchase an Eagle Crankshaft from summit racing #103523480 stock replacment. Do I now have to have this crank balanced at a Machine shop or just bolt it in, Eagles web site notes this is internal/externaly balanced crank. im putting it in 87-93 sbc 350 w/auto trans.

Thanks

 

The reason that they say int/ext balance is because the late model cranks use internally balanced front dampers and an externally balanced flexplate with a counterweight on it. If you were to bolt up the flexplate and spin the crank on a balancing machine, it sould balance internal.

I have bolted such cranks together with NO trips to the machine shop and I haven't had any problems. However, if you are going through the trouble of putting in an after market crankshaft, you might as well just do it right and get the whole assembly balanced. Make sure you take them your flexplate and front balancer too. You will be happy you did when you spin up your engine and it is smooth and tight.

 

Thanks for your help GASGZLR, I emailed Eagle and got this reply "That crank is designed to be internally balanced and you will need to have it balanced before use." even though there web site notes its internal and externaly balanced. I dont have a flexplate for the engine yet (bought it on ebay) but i'll buy one and send it off to the machine shop.

Thanks