68CamaroBlake

I'm building a 5.7 iron block LS (5.3 punched out to 5.7), and I'm checking my rod bearing vs crank journal clearances. I wanted to see what you guys thought of the results before I start installing the rods to make sure the clearances aren't too tight.

.00185
.00205
.00200
.00205
.00185
.00195
.00200
.00195



The main crank journal clearances were .002 +.0004/-.0000

Based on those numbers, I'm going to be running 5W20 oil through it.


I just wanted to make sure the clearances were't too tight as this is my first LS motor build (going in my 68 Camaro). Really taking my time with it to make sure I don't miss anything.

pdxmotorhead

How were they measured,, ?? Plastiguage or Inside-outside micrometers? (Just curious.. )

01CamaroSSTx

iTrader: (3)

↑↑↑↑Beat me to it↑↑↑↑↑

pdxmotorhead

Something to consider,, Plastiguage is measuring the displaced gap,, the rod and crank need oil pressure to center the crank in the rod bore.
Hydraulic pressure is pretty magical, so for high power tight tolerance I'd go with a GOOD micrometer and bore gauge and measure several places each to check fore oval journals and rod bores.

(This is why my question above.. )

68CamaroBlake

Measured with and OD mic and ID bore gauge. Calibrated in house at my O&G mfg facilities gauge lab.

01CamaroSSTx

iTrader: (3)

Well with that being said I think it's a little tight for an iron block build. Curios to know just how you measured the rod bores. Did you measure without the bearings installed to get the bore minus the bearing thickness or did you measure with the bearings installed on the rods after torqued? You may want to look at a different set of bearings.

68CamaroBlake

Measured with the bearings torqued down in the loose rods.

KCS

iTrader: (20)

Clearances look good for a mild build.