arc_55

Honda's spec is .0008"-.0015"
Eagles general guideline says .0020"-.0030"

Using the smallest bearing (red) this leaves me at the end of hondas specification (.0014"-.0016")

I am curious to know how much clearance you guys are using on forged rods? Will .0014"-.0016" be enough clearance?

blackeg

.0014 is probably too tight. i had a rod that was at .0013 and it was wearing the bearing substantially.

i generally shoot for .0015 to .0020. i think my current motor is between .0016 and .0019 on my rod bearings.

arc_55

damn! so i might have to grind my rod journals down slightly to get my clearance acceptable.

Can anyone else confirm bearing clearances for me?

rich7777

Yep yep.... You need to get the rods resized. Make sure your measurements are correct first though.

Copied and pasted from Laskey racing :


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Honda Bearing Thickness Chart
Here is a chart of Honda B series bearing thickness by color. To calculate actual bearing clearance, use the following formula:
BC = IDBT – ODC – (2 x BT)
BC = bearing clearance
IDBT = inside diameter of bearing tunnel (housing bore)
ODC = outside diameter of crank journal
BT = bearing thickness

Main Bearing thickness by color
Blue 2.013-2.010 mm 0.0793”- 0.0791”
Black 2.010-2.007 mm 0.0791”- 0.0790”
Brown 2.007-2.004 mm 0.0790”- 0.0789”
Green 2.004-2.001 mm 0.0789”- 0.0788”
Yellow 2.001-1.998 mm 0.0788”- 0.0787”
Pink 1.998-1.995 mm 0.0787”- 0.0785”
Red 1.995-1.992 mm 0.0785”- 0.0783”

Rod bearing thickness by color
Blue 1.510-1.507 mm 0.0594”- 0.0593”
Black 1.507-1.504 mm 0.0593”- 0.0592”
Brown 1.504-1.501 mm 0.0592”- 0.0591”
Green 1.501-1.498 mm 0.0591”- 0.0590”
Yellow 1.498-1.495 mm 0.0590”- 0.0589”
Pink 1.495-1.492 mm 0.0589”- 0.0587”
Red 1.492-1.489 mm 0.0587”- 0.0586”
Although most people do not have inside micrometers, bearing micrometers or snap gauges, you can still use this chart when using plastigage to check bearing clearance. If you want to increase or decrease a bearing clearance, you can calculate how much of a color change is necessary by looking at the changes on the chart. Remember you can mix colors for even a more fine-tuning but it would not be wise to jump more than one color. In other words, do not mix a brown and yellow bearing together to equal a green clearance value. Just use the greens together. It is ok to mix a green with a yellow or a green with a brown. When doing your rebuild and replacing bearings with like colors, you still must check your results with plastigage to be sure. Don’t assume anything. Also remember, when swapping to aftermarket rods, throw the color codes away as they will not work anymore. You need to start from scratch to obtain your desired clearance. On the other hand, you really cannot measure accurately to the nearest .0001”, so don’t get carried away on that last one ten thousandth of an inch variance

arc_55

I talked to eagle and the specification of .002-.003" is for SBC engines. General rule of thumb is .0001" x rod journal size and in my case that gives me .0017-.0018". I am going to hone the rods out larger and aim between .0017-.0022" bearing clearance.

Apparently eagle rods tend to be a little smaller and opening up the big end of the rod slightly is very common to get your acceptable clearance.

EG1834

Only if you stay within spec. You need to have the housing bore diameter within a specific tolerance in order to put proper crush on the bearing and keep it from spinning.

Gunmetal_B20_Hatch

iTrader: (9)

I just built my LS and all my bearings came out to .0012-.0015

arc_55

the connecting rod big end will be within specification i am just looking for a few tenths of a thou. for some extra clearance.

PyroProblem

Would having the journals polished give you a few more tenths? Or I wonder if it wouldnt be uniform enough on all areas of the journal...

I am going to run .0020 on my Eagle rods. The aftermarket bearings I had originally bought put me at around .0010" - .0013". Im using oem pinks to get me where I want...

Ive also always heard that you want .001" for every inch of journal diameter.

PyroProblem

Isn't that a little tight?

B and B

iTrader: (3)

That's what she said

d112crzy

Depends on the application. How high the motor is being revved, how much power you want out of it and how long you want it to last.

arc_55

well the journals on the crankshaft are hardened and coated from the factory you want to try and not to break down. According to machinists in my area even if you were to remove a tenth of thousandths off you would be there all day and your better off honing the connecting rods out to meet your bearing clearance. In my case i am talking 4-5 tenths at most so i am not going to have to worry about bearing crush being adequate.

For forged rods i would consider that a tight. I am aiming for .00018-.00021 rod bearing clearance and this is a forced induction build.

vwbased

have a nice day

BigMike0147

Have you ran this motor yet?? And if so, how long??

I just ran mine for the first time yesterday with the same clearances you specified and I didn't have any issues. I had to get red bearings however to get these clearances. I didn't know that most people were running their Eagle rods closer to .002" though. So I've got to pull my motor again due to tranny issues, and I just bought some ACL HX bearings that I plan to install to put me right under .002". I REALLY don't want to spin a bearing down the line, so I'm trying to be as safe as possible. Hopefully the extra work will pay off in the end.

vwbased

have a nice day

Gunmetal_B20_Hatch

iTrader: (9)

No, motor is going in this weekend... As already stated, I planned on using a 10w-30 oil(Royal Purple likely), not 20w-50 or other heavier oil.

I have to admit, I am a touch worried about bearing issues, but I think its going to be OK.

BigMike0147

I appreciate the insite and all you said definitely makes sense. I went ahead and ordered some new bearings yesterday, and since I have to pull the motor/trans anyways, I'll switch them out for piece of mind. I like the idea of running a heavier, zinc oil for protection as well. I plan on taking the car out one more time tonight to finish seating the rings, but I'll make sure that I let it warm up to temperature first before I start driving. I just don't have 5th gear right now, but I don't need it for the short trip I'm going to take.

BigMike0147

I think that you'll be fine as well. I just went ahead and bought the bearings since they're only $60 and it helps me sleep a little better.

However, I am going to check the clearances when I pull the rod cap of via plastiguage of the bearings I have in there now for the knowledge of what the clearances are after running the engine. My uncle, who's been a mechanic for over twice as long as I've been alive, says that after running the motor the bearings should open up a little. So if I find that mine did a little, maybe this will make your decision even better. Let us know how your startup and everything goes. I'm basically in the exact same spot you are right now, minus my whole tranny situation.