I'm normally about 4x that, give or take. I could probably relax that. on the clevite h bearings, it leaves lines, but these are just going through the protective coating. you can't feel them at all.

 

It's pretty simple really.

Measure housing bore, measure crank journal, measure bearing thickness.

Do the math and that's your oil clearance. I have built many engines using this method and not one of them leaves with the slightest spec on any of the bearings.

 

91sonoma...you haven't priced crate engines lately have you?

 

Other than a handful of import guys, I don't know of any shops that check bearing clearances the way you describe. The vast majority of machinists use a micrometer to get the OD of the journal, then zero a dial bore gauge off of that to get a clearance.

 

You must be hanging around the wrong shops then.

Every engine I have built, and every machine shop I have been to/had work done does it this way.

I'm not sure what kind of import shops You have seen, But I'm also not sure what country the engine is made in, has to do with a simple machinest measurement procedure.

Sorry, but the easiest way and best way to not damage your bearings from installing them and putting them into crush and spread without the crank being there is the method I use.

To each his own, but I'm not willing to take that risk. Esp with other peoples money.

 

In theory this should work but taking into consideration the quality and precision of your instruments, the fact that the rod may slightly compress the rod bearing diameter, the tolerance stack-up of taking 3 separate measurements, and the fact that you are dealing with measurements in the range of a few thousandths of an inch I'm not sure how good of a measurement you would get using this method.

 

this is like anything else, there is normally not 1 absolute correct way to do something. If you've had good luck doing it one way, great, stick to it.

I choose to measure the bearings directly because this is how HKE, TSP, and Joseph Potak's book do it.

 

I agree. To each his own. Every engine I have built including my own have all carried good oil pressure and ran great.

With the method I described, your only taking one measurement. If your to the point of measuring oil clearance, your crank shaft and main bore should have already been measured.

 

It's comments like this that really irritate people and make you look like an arrogant a**hole.

Who are you to say a shop is wrong or not? Who are you to say that Judson Massingill is teaching eveyone at SAM the wrong way to measure bearing clearances when they've basically been dominating the LSX all motor classes for the last several years? Who are you to say LME is checking their bearing clearances wrong when their engine just went 201MPH in LMR's Firebird last weekend? Aren't you still in school for this stuff?


A lot of the Honda guys building their engines on a stand in their garage think the way you do and set bearing clearances with the thickness of the bearing. Most of them blow up.

You shouldn't be damaging bearings by just putting them in the bores and measuring them.

The problem I see with using one instrument to measure the bore, another to measure the bearing, and another to measure the journal is a stack up of tolerances. If it works for you and the shops you've come into contact with, then thats fine. More power to you. I'm not saying any of you are wrong, because it might just fit the way you guys build engines. For me, I've found it easier and more accurate to just take a measurement off the journals and zero a bore gauge off of that. I prefer to actually see that clearance measured on a gauge with the bearings in the engine, rather than calculated on a peice of paper. Like you said though, to each their own.

 

Could you explain more? At what point do you measure the bores and journals?

 

point taken...

and who are you to say the way the other half of the machine shops measure their bearing clearances is wrong? I never said it is wrong, just said there are other ways of doing it. when I said, "your hanging around the wrong shops", I meant if your hanging around shops that are comparable to Honda guys in their garages, your hanging around the wrong shops.




my engines have never blown up, even the ones built on the stand in my garage.



your using the same 2 instruments, a dial bore gauge, and a micrometer. even stacking measurements, it's still going to come out the same as long as your consistent. and even then, to setup a dial bore gauge requires a micrometer to set the standard to calibrate the dial bore gauge which in the end, requires the same amount of measuring with the same amount of instruments.

after it comes out of the hot tank, or crate. at some point you have to decide if your crank needs turned or your block needs line honed/bored.

I apologize if I came off arrogant. But in the end, I would never rake a dial bore gauge across any bearing, especially an expensive coated or aluminum bearing. I just dont see the point when you can do it a different way that is just as accurate and do not have to assemble the bearing/cap assemblies.

 

I didn't say either way was wrong. You are the one that said there is no reason a dial bore gauge should touch the bearings, yet Sunset, SAM, LME, HKE, and many other shops all seem to disagree. I've used a dial bore gauge on at least 100 engines I've built, some making as much as 1500whp, and it never damaged the bearings or caused any ill effects.


You need three instruments for your way. One dial bore gauge to measure the bore, one OD mic for the journals, and a ball end OD mic for the bearing. When you're stacking those three measurements, there is a lot of room for error, especially if you're taking each measurement days or weeks apart. Many variables can come into play to skew your measurements, from the temperature variances (too soon out of the hot tank or after machining), to the calibration of the instruments (set to standard incorrectly or dropped), and especially if it's several different people taking each measurement (do you trust the other guy did everything correctly). By mic'ing an OD, then zeroing a gauge off of that measurement, you don't need the true measurement of the journal or the bearing bore, you're looking at that difference between the two which is exactly the measurement you're really looking for in the first place. It's more direct and leaves very little room for error. But like I said, if it works for you thats great. I'm not saying its the wrong way or that you're hanging out at the wrong shops. I just prefer my way, and it's worked well for many others in the industry.



"Just as accurate" is the part I disgree with. Sure it can be, but for reasons outlined above, it leaves too much room for error in my opinion. I've found that the little marks left in a bearing are of no consequence to an engine in comparison to getting the bearing clearance wrong. Agree to disagree I guess.

 

Agreed. I think with my build this year ill give it a shot and see if there is any variance in the two methods.

 

I know this thread is a ittle old but I'm gonna post anyway. The King bearings that are aluminum have some silicon in them which is good for alot of things .I don't know if any or all of the other brands of rod bearings have siolicon in the alum or if the king bearings have a little more or what ? I just know the King bearings have some silicon . I believe as far as which type of bearing to go with stock, race,,,,,,etc the main factor is the crankshaft material ,,,,,,,cast , forged ,,,,,,,etc . 1 more thing I have a theory about and maybe those with more experience than myself would elaborate and that is when using Plastigauge , I believe the most accurate You can get is putting 2 pieces 1 on 1 side and the other 180 deg opposite , then tighten .