Im rebuilding my engine after a spun #4 rod bearing with a new crank and new rod. Im not getting the oil clearances I want with ACL RACE HX bearings. I think the HX bearings are thinner than OEM RED bearings, can anyone confirm that?

Target for mains 1245: .0018 ~ .0020”
Target for main 3: .0020 ~ .0022”
Target for rods: .0020”

The clearance I’m getting with the HX bearings is:
Main1: .0015”
Main2: .0018”
Main3: .0020”
Main4: .0018”
Main5: .0015”
All Rods: .0015”

Mains 1 and 5 are tighter than I’d like. And all of the rods are tighter than I’d like. Technically these clearances are within factory specs but I really wanted to run looser. So that’s what I need advice on. Is it good as is or do you recommend looser clearances?

I have 3 options for looser clearances:
-I can order OEM Red bearings but I have a feeling they aren’t going to be any thinner than ACL HX bearings.
-I can cut the crank which I don’t want to do bc you lose the nitride surface
-I can have the mains and rods honed. Sure the rods are easy to hone. But the mains are risky. With steel caps the hone is going to cut more into softer aluminum. Plus I don’t want mains 2,3,4 opened up.

What do I do - Build it as is? Try the OEM Red? Or hone everything?

 

You should be fine with those clearences but you could buy oversized bearings for those two tighter ones. Oversize will actually be a smaller bearing

 

Do you mean the 025 and .25 bearings listed here? Which one is oversize?
http://www.aclperformance.com.au/us/...Bearingsus.htm

You think .0015" on the Rods are OK too?
Ive read most people target at least .0020 oil clear on rods.
Im fine with honing the rods.

 

I had similar issues with my build. The OEM red bearings will give less clearance (are thicker) than ACL HX bearings. I believe the HX's offer about .001 more clearance than a green Honda bearing.

What rods are you running?? Stock?? I used Eagle, and I had to get different rod bearings because the clearance was too tight with standard colors. If need be, you could hone the rods on the big end to get you the clearances you want. I'm running around .0018 and no issues. From what I understand a little on the looser side is always a lot safer.

 

I have on the tighter end of bearing clearences on my engine for both rod and main bearings. My engine runs just fine and has been for 25k miles. I've had my lower end apart too and my bearings are in great shape on both the rods and mains. I'm running acl dura glides which are tighter than race bearings. Bearing Clearence dictates oil viscosity selection. If your trying to. Run thicker oil then you will need to run loose bearing clearences but if your running stock clearences you run 5w30 or 10w30

 

Looks a tad tight. Im using oem pinks and reds to get my rods around. 0016 and. 0018. Even that I feel is tight. My last engine had 3500 miles and one of the rod bearings was. 0014 and looked like total hell. The others above. 0016 had noticeably less wear.

 

looks fine to me, just use thinner oil. start with 5-30 and see what you have for oil pressure. the #3 is the hot one and you have clearance there. once this engine breaks in you might very well tear it down {if for some reason your wanted to} and see your clearances a bit looser than they are now.

 

So HX is the thinnest bearing I can run. Thanks BigMike.
Rods are Pauter.

I dont want to run thicker oil. I prefer to run a standard 10w30 oil which is why I am targeting the loose end of the factory range.

So you guys think I should hone the rods to give me .0020" clearance? Should I go for more? Im OK honing the rods. Its the crank and mains that I am nervous about removing material from.

 

I ran ALCs on my mains this time around, but insist on OEMS on the rods. A preference, and also what Eagle happens to want (they actually say MANDATORY for whatever reason, but call for pinks and there was NO WAY I was getting there with pinks LOL)... However according to the Honda matrix.. The reds wouldnt get me to the .0017-.0019 I look for on the rods. I did have to have 2 big ends resized like .0003 (admittedly the difference being in a closed hand for a few minutes, I wanted them all consistent and in that range if for nothing else my OCD and having had good luck there previously. THat said I had to run the reds to get there. I dontlike to blindly trust the number/letter matrix for the mains either... measure and measure again with ball mic, figure it out from there, then plastigauge is what I do (not that it is the ONLY way, or the best... but Its worked, Ive never had a bearing issue).

The rods clearances worked out PERFECTLY as per my calculations.

Mains using the ACL glides (non race) all fell into spec first time in without even having to juggle them around on the mains. I DO believe the race bearings to be thinner... Then again Im talking an H and the bearings specs are different.

I DO run a tighter 5 then the rest though... I could look at what I scribbled down when assembling it later if you care... Last main to get oil, run a little tighter, was the theory. Its right around where youre at (IIRC even a little tighter)

Think the only one ID really like to see bigger would be 1 idf I were you, but that is only an opinion.


When initially building my motor years ago, It went pink pink green pink green to get me "in spec"... But I did have to have 1 main journal kissed with the hone...

This is a different crank in it now, and like I said I just trust the mic more than the matrix (Although if you do your math right I haven't had any issues... Motor has always made GREAT power and been super efficient) I thought the rumor was that ACLS ran "Green", are the race bearings different (I do know they're coated/treated differently)


I run Royal purple 10-30 and have had spectacualr results with these specs. Bearings look like they are new.

 

You can hone/resize the rods but make sure its done properly and the person removes metal from both rod caps first so bearing crush is not effected. Crush is very important, its specially important on a high power output engine. If you havent got the right amount of crush you'll be a lot worse off that how you are now.

I think you should just run OEM on the rods. I'd be happy with .0018-.002.

 

Absolutely agree 110 percent with all of this. The crush threshold is super important.

 

OEM Red bearing won't give me any more clearance. ACL Race HX is thinner. I dont have an OEM Red to mic so I cant say for sure. Believe me, if OEM Reds were thinner all my problems would be solved.

I mic'd the ACL Race HX bearings. Mains are .0775" and rods are .0580" but my micrometer only has increments of .0005". According to Earl's chart those are both thinner than OEM Red.

And regarding the crush they need to mill the caps first then hone the bore, correct?

Extralargenog, whats your logic to running a tighter main5? Ive had issues in the past with oiling to the #4 rod bearing (which is fed by main5) so I am curious.

But you cant just hone a single main can you? they run it through the entire block. But if I were to have them hone the mains Id want #1 and #5 enlarged. What are your feelings about honing a steel cap and aluminum block? Wouldnt the hone naturaly eat more into the softer aluninum? Two local machine shops said this is tricky.

 

Muck,
Not to Highjack your thread, but I had the same concerns you do with a pre-assembled engine shown here in the build sheet. My thoughts were run some 10w30 and see what happens. I was hoping maybe someone could take a look at this and see if I should be concerned about this as well and maybe answer both of our questions.

 

Sorry i only quickly flicked threw your thread...

yes, some shops just torque the caps down and hone away without any care. If you use a decent machine shop (which i imagine you do) then you should be fine.

 

this doesn't make sense. you use thick oil with loose clearances for pressure. in your case, since you're within factory spec a standard 5-30 or if for some insane reason you want 10-30 is is probably going to hit just fine

 

why not get another crank to try?

 

your bearing tolerances are ok, maybe #3 main a tad tight. i think your ring gaps are off. top gap should be low .020 range, 2nd ring mid .020's. they should not be the same gap as it looks like you have .019

 

Racebum, is it better to run big clearances and thick oil over factory clearances and normal weight oil?

Casey, I just had this crank balanced and micropolished. But Ill consider it if its cheaper than an align hone.

 

this is subject to debate. i read an article about NASCAR engine building recently that talked about going tighter rather than looser which had been the norm.

actually, here's the link, great short article

http://www.pera.org/articles/Cranksh...g%E2%80%A6.pdf

now this is what's going on there. obviously engines that are under extreme punishment

but

all i was saying in your case is that you are already so close....i just don't see the point in going for that extra .0003

 

ok well i was gonna argue that .0015 is exactly what the service manual recommends for the connecting rods but thats a B18B, im showing .0013 to .0020 for the B18C1, with a service limit of .0024

 

The coating on the acl race bearings tightens everything up a tad... Try uncoated king standard bearings i have builts countless motors with these, a polished crank and an align hone...

 

Honing bearing bores is tricky. We lose bearing crush and the mains are tough to keep round bc of the two materials. So it sounds like turning the crank is safer. But then you lose the nitrided surface. So Im in a lose lose situation here.

Spawne - You are correct, it is within factory range. But dont you think I should target the loose end of the range on a motor turning 9k and making 500+?

 

well if your rod clearances are indeed .0015 on a B18C1 engine, then your not exactly on the loose end, your in the middle...actually a little closer to the tight end, because apparently you have up to .0020 for service spec on the rod clearances. Your 2,3 and 4 on the mains are out of spec and on the loose end, thats what id be concerned about, but as far as i know the mains you dont have nearly the strictness of the rod bearings as the crank merely floats on the mains, and that would be more for your oiling to dial that in better.

 

my concern would be the variation between the tight rod clearances and the loose main clearances, for oiling purposes at a certain weight

 

I'm pretty sure you'll be able to get that crank retreated. There are places over here what do it so they'll definately be places over there in the US. Do you know the depth of the treatment ?