whats up guys? im building a 306. i have a crank that is turned ".010-.010". i have had an issue when i tried to put the crank back in the block with new bearings. when i torque it down it wouldn't turn. so i stopped and tried to figure it out. i took out the #2,3,4 main bearings just leaving in # 1 and 5. then set the crank on just those 2 bearings to see if the crank was straight. i did not torque them down or anything...is that a good way to see???? when i turned the crank the needle moved about .003 or so. that seems like too much and that is the problem as to why it wont turn when torqued down.

please let me know what i should do..... about how much is it to machine if farther? or am i better off finding a new crank???

 

Did you plastigauge it yet?

 

When you torque them down all the way you're gonna have to put alot of ass behind it to turn it. Its a total fresh setup. I had this issue with Joker Instituted's motor when I built it. Cant stress enough to lather the cylinders and everything on the bottom end in assembly lube. Redline works awesome!! The only time you should have to turn it is when you're installing the timing setup and you wanna avoid turning it too much unless you lubricated the fuck outta it.

 

That is totally incorrect. Fresh or not, when the crank is installed and the main caps are torqued to spec, the crank should turn free. When you twist it by hand, it should be able to rotate by itself. If it doesn't, there is something wrong, bearing clearance to tight, bent crank, etc. I would assume the shop would have told you the crank was bent when they turned it down. Did you have the block align honed? Maybe it isn't a problem with the crank at all.

 

Good advice here.

 

Thats odd, because after 12 engines built I have never been able to turn a shortblock over by hand. Please explain what im doing wrong because all the engines ran perfect.

 

I didn't say you would be able to turn the shortblock over by hand, I said you should be able to turn the crank over by hand. Once you add 8 rods and pistons to the mix, it's a whole new ball game. LOL.

 

Please define "by hand". I have always been able to turn the engine in the engine bay by using my hands on the crank pulley. And right after building the 5 or 6 that I've built (I know I know LOL) I've always made sure to turn the crank after installing each rod/piston. But I've only done 5 or 6. LOL Haven't needed to do any more than that yet. All mine were still running till I sold them. LOL

 

Crank torqued in block should spin smooth as butter....very easy. add piston and rings, thats were the drag comes in.

Correct bearings?
Did the block go to machine shop with the crank?

 

Steve's Crankshaft in Pinellas Park does a good job of handling problems like that. It should be less than $100 to get it reground.

Brian
EFI-Unlimited

PS: This thread is a great example of the perils of internet wisdom....