Hello all. I have spent most of the day cleaning my block after the machine shop boring it, measuring everything, and plastigauging it.

Well here is what I have and my problem

B18a1 LS crank

Rod Journal Diameter - 1.7708
Golden Eagle Big Bore Dia.- 1.888
ACL STD thickness - .059

So if I do the math 1.8890-1.7708-.059*2 = (.0002") WTF!

Even when I plastigauged it second guessing my mics it was much wider than .001 and seemed to almost be completely smashed...


I'm trying to understand why I'm having problems with my Rod Journal clearance.... pllllleeeeeaaaaaaassssssseeeee give me an idea!

 

well the more I think about it the more I understand it...

1.8890 - 1.7708 - .059*2 = .0002" (almost no clearance)


BUT if I order oem bearings sized

1.8890 - 1.7708 - .0580*2 = .0022" BUT they dont have bearings that size <---

I just assumed Eagle made their rods or ACL made their bearings to accomidate for one another. But am I right in the assumption that the bearings are wrong?

 

I just double checked all my measurements

Rod - 1.889
Crank - 1.7708
bearing - .0590

 

help

 

The direct measurement and the plastigage measurement corroborate with each other.

What is the specified stretch on the rod fasteners? Are you within the specified range when loading the bolts? Maybe there's too much tension in the bolt.

You could need a HX bearing and possibly a hone of the ID's of the rod big end. I don't think an OEM bearing would give you the clearance you need given that a std-sized ACL bearing was so tight.

 

That's an odd one. ACL Race bearings would give you an extra thousandth, 0.0012" is still too tight.

IN VTEC, are HX bearings different?

 

well I slept on the matter and decided to go outside and forget all my measurments and plastigauge it one more time. I realized that I over tq the rod bolts when I seen there are 3 different types of 5/16th rods one calls for 65 on calls for 75 and one calls for 43. Turns out mine was 43 ft/lbs. So I threw out my first plastigauge reading immediatly and re-did it.

Now I'm withing specifications I believe. I'm a really close if not slightly passed .015.

Eagle calls for .020 rod clearance so I still seem to believe I'm to tight. Would you all like a pic of the plastigauge?

 

 

I suppose I could get the crank micro-polished. That would take around ..002-.003 and put me with-in specs?

The other option is to go with Pink OEM bearings and put me closer...

 

Or ACL Race bearings and introduce an extra 0.001" into the mix. Might be a little cheaper than pinks, and there's nothing wrong with a performance motor being a little loose.

 

Thats still tight. I would be right at .015 or more like .0155. Anyone see a problem with getting the crank micro-polished? I was reading the cranks service limit is 1.7707 and I'm damn close to that now at 1.7708.

I dont see what the problem is other than Eagles rod bore is to small

 

No, it would be closer to 0.0021-0.0023", which is serviceable and even ideal for a performance application. 0.015-0.0155" is so loose you'd have oil pressure problems and spin a bearing in short order.

That advertised service limit is the thickness of the crankshaft's surface hardening, which has nothing to do with the real world. As long as you have oil pressure, the bearing never scrapes the crank and a hardened journal surface is irrelevant. Any loss of oil pressure at the power levels a turbo Honda produces will shitcan the crankshaft regardless of a surface hardening. I've been through a number of turned Honda crankshafts that were not re-hardened afterwards and just like everything else that's never had a hardened journal to begin with it works out just fine.

 

The HX bearings are the ACL Race bearings that provide the extra .001" of clearance. Throw away those rod bolts and buy new ones. They've probably been stretched beyond the yield point and beyond the elastic limit.

I would hone the rod's before cutting into the crank anymore. Micropolishing will only remove a couple tenth-thou's.

 

Thanks, I didn't know that about the HXs.

 

Throw away the rods? They are brand new from GE?

I ment if I polish the crankshaft I could get a clearance around .0016-.0018. Seems like .0021-.0024 is a little loose.

 

no, throw away the rod bolts, and get new ones, is what he suggested. see what the measurements are on the other ACL options. there's Standard, race standard, and race extreme or some crap. thus giving you 3 thicknesses to choose from.


And to joseph davis. .0015 is TIGHTER that .0021 as it is a smaller clearance, not looser.

 

Yeah .0015 is tighter but I miss typed the measurement saying .015 which is much looser.

I'm tried to find other thicknesses in ACL but all I can find is the extra .001. Which scares me because of how loose it will be.

I only tq on rod that much. I will replace those rod bolts as mentioned I know I doubled their recommended tq specs..

 

get an oem bearing?

 

yeah but I could polish the crank and be right at .0016-.0017 clearance. Which to my understanding is perfect for daily driving. You all think thats a bad idea?