I've got a set of new Crower rods (B93749B-4 to be exact) for my build. I've had all my bores and journals measured by the shop to calculate my clearances. My crank measures out perfectly in spec on every journal, almost dead center of the range.

Rod Journals are all exactly 1.7714", and all my rod bores are 1.8902". I want my rod bearing clearances to at .002" but my clearances with OEM red bearings is only at .0016".

I want to use OEM bearings like the rest of my build, but I would like to NOT be at the ragged edge of specs on the thinnest OEM bearings available. I'm not keen on modifying the rods either because they are so expensive and because I don't want to lose proper bearing crush.

So, can I safely hone the rods' big-end bores half a thou and safely get away with pink and/or red bearings for my .002" clearance? Am I over-thinking this, or is there a better alternative?

(More info in my build thread, link in my signature)

 

Honing rods is very common and inexpensive. I also shoot for .0020" on rod oil clearances.

 

You should micro polish the crank first to get more Clearance and hone the big end out last.. Also a micro polish will help to make sure the crank doesn't have any egg shaped journals

 

Muckman-
Thanks for the input. Crower said .0015-.0016 should be good for my goals, but .002" seems to be what everyone else recommends. I'd rather be too loose than too tight.

Hidenplanvew-
I've always heard that polishing the journals is never an exact science, and being that my crank is practically perfect in all aspects, I really don't want to touch it.

Any more input or concerns I should have with honing out the rods?

 

A little loose is good as long as you have good oil pressure. You can always run thicker oil if its too low at operating temp.

Ive always heard the same about polishing journals. Its harder to keep it round when polishing, especially when removing material. I think honing is the way to go, its cheaper and safer but talk to your machine shop.

 

NEVER hone the rods!!!! This can affect how well the bearings stay in place. Buy some ACL HX bearing and you will get your .002.

 

Well that throws a wrench in the works...

 

lol hes technically right, increasing the OD means you lose bearing tang support but half a thou wont. Talk to your machine shop!

 

What he's saying does make since, but I honestly don't think it'd hurt. However, I'm running ACL HX bearings with my Eagle rods with no issues, so the choice is yours.

 

Yeah, I know with machining them I run the risk of losing my crush that keeps them in place.

I just called the shop and the guy said that it's not likely that I'd lose my crush by opening the rods .0005", but he'd choose the +.001" bearings before touching the rods.

So... With HX bearings providing .001" more clearance than standard bearings, are the standard bearings roughly equal to OEM green bearings?

 

Acl gsr/type r Standard bearings are listed at .0591, Oem Green are 0.591-0.590
Aclgsr/type r Hx bearings are listed at .0586.

 

Thanks Fink. If that's the case, then HX bearings are no smaller than the red OEM bearings that are giving me .0016" clearance.

 

Another option you may have is re-tanging the side of the rod and cap that isnt tanged and simply turning the rod around. Well after you have it honed to the spec you need to get your desired clearance.

 

And what purpose does that serve? My tang side goes on the exhaust side, correct?

 

If you have to hone the rod and the current tangs are compromised, tang the other side of the rod and cap.

 

The HX bearings should give a bigger clearance than your red bearings. It should be about another .0002" of clearance over the red bearing from Honda. That would put you at .0018".

 

i once polished the backside of the bearing to give me the clearance i wanted on a b16. it worked made 400hp and drove 25K miles before i sold the setup.

 

Bingo! Here are my results with HX bearings. It's not .002", but I'm satisfied with the results given I didn't have to modify any parts and risk compromising the bearing crush.

Thanks for all the input guys!

 

Just a heads up for anyone thinking about honing big ends of rods to increase bearing clearance. Dont do it..But I doubt anyone who owns a pin hone/rod resizer would do it for a customer anyway..

 

You bumped a 3 year old thread to say something that was already said earlier in the thread and something most people already knew?

Good job...