jacobm99

iTrader: (2)

Checking my main bearing clearances with a mic and dial-bore gauge, my main bearing clearances come out at 0.003/0.0035 and becuase of the variance (eg different readings for the same main cap bearing- depending on where the gauge sits) I decided to double check with plastigauge, which yields measurements of 0.002 (????)

1) I've heard that platigauge measures tight, but isn't this a little too much of a difference?

2) Assuming that my mic's measurements are more accurate, shouldn't the fact that my crank journal measurements are at factor spec (2.5590) mean that there wouldn't be a need to get oversized bearings (since factory clearances are 0.0007-0.00212)?

jacobm99

iTrader: (2)

Anyone?

ChucksZ06

iTrader: (9)

Do not trust plastigage. You need to make sure you are using micrometers correctly. Are you torquing main caps before you measure?

jacobm99

iTrader: (2)

I suspect I am using the micrometer/ dial-bore gauge right, but cannot be sure. Here's my process: Using the micrometer, I zeroed the gauge using the 2" rod included, then I open it up and measure the journals (which measured 2.5590). Then locking that measurement on the micrometer, I insert the dial-bore gauge and set the dial to zero. I then inserted the dial-bore gauge in the mains and determine how much clearance based on how much the needle separates from the zero. Make sense?

And yes, I'm torquing the main caps in the correct sequence and torque/angled settings.

jacobm99

iTrader: (2)

No one else has had a similar experience or advise to impart?