[Cosmo]

Lolita's new 388 incher is going together. The crank thrust bearing clearance is only about 2.5-3 thousandths of an inch instead of the 4-8 it should be. Any ideas from you other engine builders ? I've never had this happen before..?

 

[camachinist]

Nothing some 600 grit on a piece of glass or a surface plate couldn't solve... that would work out to about .0005-.001" per side. I'd recommend checking your work with an outside mic to prevent uneveness. Personally, I'd be inclined to just Scotchbrite the thrusts and run it as is....is this a manual trans car?

Are you sure you're getting an accurate reading from your dial indicator....? I usually use my .0001" universal (.015" per revolution) indicating on the crank hub at the rear of the engine and use a screwdriver to move the crank... if using a plunger-style indicator, be sure the plunger is parallel to the crank CL...

Good luck!

 

[mlnielsen]

Is there a freeze plug in the back where the cam is? Maybe it's installed too deep.

 

[Cosmo]

Thanks, guys. Yeah, Pat, dial indicator at the crank snout, parallel to the crank axis. I'm tearing it back down today to do some more stuff I thought of ( radius oil drainback holes, etc.) and I'll address the crank thrust clearance while I'm at it. C4, by the way..

 

[camachinist]

Remembered something when I woke up this morning...amazing huh? *G*

Did you set the thrust by bonking the crank back and forth with a dead-blow mallet? Sometimes that helps get a more accurate reading...

Also, while you're doing your checking, you could bolt the C4 bellhousing on and check for runout of the crank to the pump register. I usually also dummy up the trans with at least the front pump and check the converter for proper clearance to the flexplate. A lot easier to fix now then when everything is together.

Have fun!

 

[Cosmo]

Hi, Pat,

Yeah, I've always used the mallet method. The screwdriver method asserts an
off-axis thrust, and I don't think it gives accurate results.

The cool thing about the other checks is that I bought a spare trans a few weeks ago to build while the car is still running with the old engine. The other checks become easier yet under those circumstances !