Experienced Rebuilders Input needed

[JayB12]

It's been a while since I've actually had to rebuild an engine and I measured everything up and wanted some second opinions on my clearances and some advice.

I'm doing my engine and one for a friend right now.

Mine is a 6-bolt. I'm using King Racing bearings with the extra clearances on both.

Mains are .0025-.0035" and the rods are .0030-.0040" is that too loose? I also have both sets of the standard bearings as well if i were to need to change them. Car will be making in the 700whp range and is typically summer/track use only.


Second engine is from an Evo 8 It actually spun both the 2 and 3 Mains, but after taking it apart the damage looks very minimal surprisingly. Car ran, just had 3-5psi of oil pressure. All bearings were fairly worn. Looks like it was incorrectly assembled. (had the upper and lower mains all mixed up) It only had about 3-5k miles on a full manley 2.3 rotating assembly.
I'm going to start by measuring all the main bores. Anyone know the spec?
Also any advice? Car has a FF FP3794 ect. So it will have to take some abuse as well.

 

[SasaniFab]

What I usually do is measure everything with a dial bore gauge and verify my results with some plastigauge. Those 6 bolt values are within spec for the mains, what rods are you using? .004 is at the end of spec, my motors generally run .0025-.0030 for rods and mains. I don't have balance shafts and run 20w50 oil

 

[JayB12]

Eagle H Beam rods. Like I said, both of those are using +.001" King Race Bearings I can Use the STD set if need be. I did use both the bore gauge and plastigauge methods. I just wasnt sure what everyone built race-spec motor clearances to.

 

[pneumo]

I wouldn't go bigger than .0035". I've run as tight as .0020 on mains and rods and it did great at over 650AWHP and 9200 rpm rev limit.
Also, you can mix bearings to adjust the clearance in fine increments. For example, if you want to tighten the rod clearance by .0005, use the King +.001 on the bottom and the STD on the top.

 

[JayB12]

What would be the "target" if you were to do one perfectly? I've heard to do the rods slightly looser than the mains, or should they be relatively the same?

 

[pneumo]

What would be the "target" if you were to do one perfectly? I've heard to do the rods slightly looser than the mains, or should they be relatively the same?

Aim for .0025" for both rods and mains.