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 Blocks / Cranks/ Rods and Pistons
 main & rod bearing clearances
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beertracker
Cochise

452 Posts

Posted - 25 Jan 2019 :  01:53:14 AM  Show Profile  Reply with Quote
I am getting ready to check main & rod bearing clearance on my 455 using plasti-gage. Can some one tell me the clearance ranges for main & rod bearings.

My setup is 455, 60lb oil pump, factory crank cut .010" on main and rod journals.

Thanks,bt

Edited by - beertracker on 26 Jan 2019 12:42:15 AM

Corncob2061
Crazy Horse

USA
589 Posts

Posted - 25 Jan 2019 :  1:55:50 PM  Show Profile  Reply with Quote
.002-.0025 on the rods, I prefer closer to .0025.

.003-.0035 on the mains.

Jay
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beertracker
Cochise

452 Posts

Posted - 25 Jan 2019 :  5:29:14 PM  Show Profile  Reply with Quote
Forgot to ask how many sheets of plasti gage would it take to do a engine? I am planning on checking each main and rod.

bt

Edited by - beertracker on 26 Jan 2019 03:29:09 AM
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tjs44
Crazy Horse

USA
650 Posts

Posted - 25 Jan 2019 :  6:48:15 PM  Show Profile  Reply with Quote
Do it right,get a mic!JMO,Tom
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 25 Jan 2019 :  8:39:55 PM  Show Profile  Reply with Quote
I use a mic to check and double check with plasti gage. Might just be out of habit, but I have caught some line honing issues with the plasti gage that the mic missed. Not every machine shop is equal, one we use sometimes gets in a hurrry. Sometimes when something seems off, I triple check in two dimensions on the mains for line bore.

Usually 2 sheets catches a engine. Jay

Edited by - Corncob2061 on 25 Jan 2019 8:46:57 PM
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beertracker
Cochise

452 Posts

Posted - 21 Mar 2019 :  4:39:19 PM  Show Profile  Reply with Quote
deleted

Edited by - beertracker on 25 Mar 2019 3:25:00 PM
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beertracker
Cochise

452 Posts

Posted - 04 Nov 2019 :  6:33:59 PM  Show Profile  Reply with Quote
I know you are supposed to use a dial bore gauge and micrometer to measure main bearing clearance. I wondered if any one here has had luck using a telescoping gauge and micrometer to measure main bearing clearance. Use the micrometer to get the crank main journal OD and the telescoping gauge to get the main bearing ID then use the micrometer to measure the ID. Seems like it should work?? A telescoping gauge set is cheaper than a dial bore gauge. bt
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beertracker
Cochise

452 Posts

Posted - 06 Nov 2019 :  2:17:00 PM  Show Profile  Reply with Quote
Would this dial bore gauge work for measuring main bores and rod bores? https://www.summitracing.com/parts/sum-900041?seid=srese2&utm_source=bing&utm_medium=cpc&utm_campaign=Brands+|+S&utm_term=4581390076893073&utm_content=GSAPI+5ba29eacb7da9

This one reads in steps of .0005" but I thought for main and rod bores we need one that reads increments of .0001"?



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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 10 Nov 2019 :  11:06:34 AM  Show Profile  Reply with Quote
What does the telescopic gauge set look like? Are the ends sharp enough to get good measurements on the bores? Do they have any kind of feel to them when your extending them for full extension in the bore? Jay

Edited by - Corncob2061 on 10 Nov 2019 11:13:43 AM
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 10 Nov 2019 :  2:41:22 PM  Show Profile  Reply with Quote
The only differences I have noticed going between my dial bore gauge and telescopic gauge is once the dial bore gauge is set the measuring goes faster because you can go off the dial versus checking the telescopic guage with a mic for every measurement. One telescopic gauge I have used had a mic built into it to. A little more tedious to read though. I have never used a cheaper telescopic gauge, maybe they not as accurate? They are price wise pretty economical, I wonder if the accuracy goes south on those? Jay
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 10 Nov 2019 :  3:32:43 PM  Show Profile  Reply with Quote
These telescopic gauges all came with in .0002. For what they cost ($66). That is pretty good accuaracy.
A comparison:

https://m.youtube.com/watch?v=ugL_h6PoKJI
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beertracker
Cochise

452 Posts

Posted - 10 Nov 2019 :  5:56:55 PM  Show Profile  Reply with Quote
quote:
Originally posted by Corncob2061

What does the telescopic gauge set look like? Are the ends sharp enough to get good measurements on the bores? Do they have any kind of feel to them when your extending them for full extension in the bore? Jay



I am using a new Pittsburgh 6 pc telescoping gauge set 5649 from Harbor Freight.

The telescopic gauge is spring loaded and the arms have rounded edges. The arms fit well inside the main bore housing. I offset the arms 10 deg. from vertical then lock in place and force the measurement onto
the gauge. I can feel the arms move inward as I push down on the gauge handle and the measurement is forced onto the gauge. The gauge arms do not move as I take the mic measurement.

When placing the gauge arms inside the bore I am working against opposing spring pressure. bt

Edited by - beertracker on 10 Nov 2019 6:06:33 PM
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beertracker
Cochise

452 Posts

Posted - 10 Nov 2019 :  6:28:16 PM  Show Profile  Reply with Quote
quote:
Originally posted by Corncob2061

These telescopic gauges all came with in .0002. For what they cost ($66). That is pretty good accuaracy.
A comparison:

https://m.youtube.com/watch?v=ugL_h6PoKJI



After reading the link above. It's time to throw my Harbor Freight telescopic gauges away. Wish I had known this before I bought them.
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 10 Nov 2019 :  10:54:48 PM  Show Profile  Reply with Quote
quote:
Originally posted by beertracker

quote:
Originally posted by Corncob2061

What does the telescopic gauge set look like? Are the ends sharp enough to get good measurements on the bores? Do they have any kind of feel to them when your extending them for full extension in the bore? Jay



I am using a new Pittsburgh 6 pc telescoping gauge set 5649 from Harbor Freight.

The telescopic gauge is spring loaded and the arms have rounded edges. The arms fit well inside the main bore housing. I offset the arms 10 deg. from vertical then lock in place and force the measurement onto
the gauge. I can feel the arms move inward as I push down on the gauge handle and the measurement is forced onto the gauge. The gauge arms do not move as I take the mic measurement.

When placing the gauge arms inside the bore I am working against opposing spring pressure. bt



I looked up the Pittsburgh set up, they had pretty good reviews, considering that is a $16 set. As near as I can tell accuracy for that set is closer to .001 or slightly better, according to some of the online reviews. Jay

Edited by - Corncob2061 on 10 Nov 2019 10:59:36 PM
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67drake
Sitting Duck

Azerbaijan
1551 Posts

Posted - 12 Nov 2019 :  11:30:46 PM  Show Profile  Reply with Quote
Beer tracker, I have the exact same dial bore gauge you posted. It works fine. I bought it maybe 5 years ago but I don?t think I paid more than $65-70 or so for it. You might want to shop around. I think I got mine from Shars. If that?s spelled right?


71' GTO Original 400 M20 3.23 posi
13.95@102.1 MPH on street tires
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67drake
Sitting Duck

Azerbaijan
1551 Posts

Posted - 13 Nov 2019 :  02:43:02 AM  Show Profile  Reply with Quote
Here ya go
https://www.shars.com/2-6-dial-bore-gauge-0-0005

LOL. I must be getting old. I just pulled the 221 V8 out of my ?62 Mercury for an overhaul. I was going to use my snap gauges and micrometers to take measurements because I forgot I even bought the dial bore gauge. Then I found it in my toolbox while looking for my pulley puller! BUT I remember exactly what I paid for it!


71' GTO Original 400 M20 3.23 posi
13.95@102.1 MPH on street tires

Edited by - 67drake on 13 Nov 2019 02:57:19 AM
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beertracker
Cochise

452 Posts

Posted - 16 Nov 2019 :  10:17:28 PM  Show Profile  Reply with Quote
I am using Sealed Power 151M10 main bearings for my 1974 Pontiac 455 engine. Four of my main tunnel bore clearances are out of spec. Please look over my data and tell me if this is something that must be corrected. My crank mains are cut .010".

Main Bore Diameters. Spec range is 3.4380-3.4385". With caps torqued and no bearings installed.

Main Bore #
1 3.4381 spec. 3.4380 variance -0.0001 in spec
2 3.4372 0.0008 too small
3 3.4376 0.0004 too small
4 3.4365 0.0015 too small
5 3.4371 0.0009 too small


Edited by - beertracker on 16 Nov 2019 10:23:27 PM
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beertracker
Cochise

452 Posts

Posted - 16 Nov 2019 :  10:27:31 PM  Show Profile  Reply with Quote
I tried to edit the data above but no luck. It's not the easiest to read but 1-5 is main bore #, next 5 digits are measured main bore size, next 5 digits are difference of 3.4380 and measured value.
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tjs44
Crazy Horse

USA
650 Posts

Posted - 17 Nov 2019 :  10:43:00 AM  Show Profile  Reply with Quote
Looks like you need a line hone if your numbers are correct.Tom
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beertracker
Cochise

452 Posts

Posted - 17 Nov 2019 :  3:50:53 PM  Show Profile  Reply with Quote
I paid my shop to run a align bore test. They told me I didn't need one. I measured the main bores with a calibrated Fowler .0001 resolution mic and set of telescoping gauges.
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 17 Nov 2019 :  6:12:56 PM  Show Profile  Reply with Quote
Just a guess, but some of the cheaper telescopic gauges do not have very rounded ends. That might have decreased the measurement some. IRC, side by side with the higher end tools you can add .0008-.001 to the measurements because of the arc difference.


The one I would be concerned about is the no 4 thrust. You do not want that one to be your tightest bearing spec. Jay

Edited by - Corncob2061 on 17 Nov 2019 6:14:35 PM
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beertracker
Cochise

452 Posts

Posted - 17 Nov 2019 :  7:31:35 PM  Show Profile  Reply with Quote
Looks like I have two choices buy a more expensive telescoping gauge and throw away my Harbor Freight ones or buy a dial bore gauge. I vote for a dial bore gauge like this one; https://www.shars.com/2-6-dial-bore-gauge-0-0005

I will probably use the dial bore gauge for one project and never use it again. I hate buying single use tools but it can't be helped.
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beertracker
Cochise

452 Posts

Posted - 17 Nov 2019 :  7:43:19 PM  Show Profile  Reply with Quote
quote:
Originally posted by Corncob2061

Just a guess, but some of the cheaper telescopic gauges do not have very rounded ends. That might have decreased the measurement some. IRC, side by side with the higher end tools you can add .0008-.001 to the measurements because of the arc difference.


The one I would be concerned about is the no 4 thrust. You do not want that one to be your tightest bearing spec. Jay



My Harbor Freight telescoping gauges have rounded edges and it looks like a 3/32" radius for the rounded edges depending on the size of each gauge. I was hoping I wouldn't have to buy a dial bore gauge since I already have a telescoping gauge but it' not going to work that way. gary
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tjs44
Crazy Horse

USA
650 Posts

Posted - 17 Nov 2019 :  8:25:00 PM  Show Profile  Reply with Quote
But you still wont know if the block needs a line hone will you?You know the bore sizes but wont know if they are all parallel?Tom
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beertracker
Cochise

452 Posts

Posted - 21 Nov 2019 :  7:46:32 PM  Show Profile  Reply with Quote
I bought a Fowler dial bore gauge and found this how to video. https://www.youtube.com/watch?v=_3bNKtdjBM4

Edited by - beertracker on 22 Nov 2019 08:36:25 AM
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 22 Nov 2019 :  10:21:14 AM  Show Profile  Reply with Quote
Fowler is a nice bore guage for the money.

It will be interesting to see what you come up with for a difference between the Fowler bore guage and the ultra cheap Harbor freight telescopic set. I am guessing .0008-.001 increase across the board on readings with the Fowler. You already plastigaged the crank and those measurements were pretty consistent across the all the mains, they were just tight on clearence. When plasti guage gets old or sets on the shelf very long it often reads tighter than actual specs, but it will do so pretty consistently. I think your good on the line bore, if anything the bearing themselves are slightly undersides, .0005 undersized is pretty common with a FM bearing. It is always a possibility the main bores are in the min side of spec and which add more crush, that looses another .0005 on the overall clearance. Together that can add up to tighter crank specs. Most shops will not line hone the mains bores if they come with in the recommended range. Jay
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beertracker
Cochise

452 Posts

Posted - 09 Dec 2019 :  3:33:45 PM  Show Profile  Reply with Quote
Here are the numbers comparing Harbor Freight telescoping gauge set vs Fowler 2-6" bore dial gauge (BDO). This is measuring rod big end ID, bearings are installed and caps torqued. The telescoping gauge gave 5 measurements of 2.240" and 3 measurements of 2.241".

The BDO gave 7 measurements of 2.242" and 1 measurement of 2.241". A difference between the two instruments of .002". Once I learned how to setup and use the BDO it was a piece of cake taking measurements.

Next I will plug numbers in my spreadsheet and calculate rod bearing oil clearances. The Shar BDO mentioned above looks like the Fowler and is cheaper in price. I can't explain the price difference.
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beertracker
Cochise

452 Posts

Posted - 09 Dec 2019 :  10:41:19 PM  Show Profile  Reply with Quote
Here is the big end rod bearing clearance using vernier caliper and dial bore gauge. Formatting is not good but 1-8 are rod # and next column is clearance.

Clearance
rod # 1 0.0027
2 0.0023
3 0.0024
4 0.0026
5 0.0028
6 0.0020
7 0.0027
8 0.0027

Edited by - beertracker on 09 Dec 2019 10:43:21 PM
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