Main Bearing Clearance
December 15th, 2017, 08:40 AM
#1
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Main Bearing Clearance
One .0035
Two .0037
Three .0046
Four .0039
Five .0038
Rotating assembly is stock with main studs, ARP rod bolts, and .060 cast pistons. Max RPM 5,500.
Are these clearances appropriate?
Two .0037
Three .0046
Four .0039
Five .0038
Rotating assembly is stock with main studs, ARP rod bolts, and .060 cast pistons. Max RPM 5,500.
Are these clearances appropriate?
December 15th, 2017, 02:50 PM
#4
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So your variance is most likely in the crank then. However the rear main typically has almost a full .001 more clearance than the rest, apples to apples, because the rear shells are just a bit thinner. Hmmmm....
Either way it'll work, you'll just need to use a good 20W-50 oil for the film strength.
Hope this helps.
Either way it'll work, you'll just need to use a good 20W-50 oil for the film strength.
Hope this helps.
December 15th, 2017, 02:59 PM
#5
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There is a "cheap" fix but you'd need some accurate measuring tools!
Without accurately knowing all your numbers it appears when they did the align-hone they went well over the high limit! Just guessing here!
Thanks, Gary in N.Y.
P.S. You don't say what size the crank is now but if it's "standard" you might try to get some .001" under mains, it will definitely help.
December 15th, 2017, 03:29 PM
#6
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Location: Ontario, Canada
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I have had to hone out many bushings for punches over the years and could hold within .0001 with ease over 4" if I tried.
Now having said that, I've never honed an engine block and wouldn't know how, but, I'm surprised an automotive honing machine can be .0011 out from the figures you posted.
Machining and holding .0011 I can see it, but honing I'm shocked.
I hope your build will be Ok.
Eric
Now having said that, I've never honed an engine block and wouldn't know how, but, I'm surprised an automotive honing machine can be .0011 out from the figures you posted.
Machining and holding .0011 I can see it, but honing I'm shocked.
I hope your build will be Ok.
Eric
December 15th, 2017, 03:52 PM
#8
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Use the dial bore on the tunnel, then use a ball mike to mike the bearing shells. Then mike the crank and do the math from there.
December 26th, 2017, 01:32 PM
#11
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for an E-block 400 you are flirting with danger and asking for trouble with those loose clearances. 10-1 bet your crank grinder ground your crank to the "low side" just like he does for dem "Chebbies".Its my experience that if you do not instruct the crank grinder to put it right on the "nuts" - it will come back to you ground to the low side.
Actually i was being nice above --- the real truth is that that motor will NOT live with .0046 on the center main! None of them should be over .003. You will have low oil pressure and will soon lose a bearing. Im gonna assume that you will also find your rod bearing clearances way over .002 also. another ticket to disaster.
I only lost 8 of these motors until i became a believer in running stock factory bearing clearances! My current race motor carries 85psi cold and 60 psi hot and i do NOT use oil passage restictors either!!
Do what you want, but you asked for advice, and i volunteered mine. If it were me , i would get the crank taken to .020 (exact) - ( if it is .010 now?) and make it right. if it is already .020 -- get another crank unless you want to get the crank nitrided (tufftride).
MOO'
Tweed
Actually i was being nice above --- the real truth is that that motor will NOT live with .0046 on the center main! None of them should be over .003. You will have low oil pressure and will soon lose a bearing. Im gonna assume that you will also find your rod bearing clearances way over .002 also. another ticket to disaster.
I only lost 8 of these motors until i became a believer in running stock factory bearing clearances! My current race motor carries 85psi cold and 60 psi hot and i do NOT use oil passage restictors either!!
Do what you want, but you asked for advice, and i volunteered mine. If it were me , i would get the crank taken to .020 (exact) - ( if it is .010 now?) and make it right. if it is already .020 -- get another crank unless you want to get the crank nitrided (tufftride).
MOO'
Tweed
Last edited by Chesrown 67 OAI; December 26th, 2017 at 01:34 PM.
December 26th, 2017, 04:37 PM
#12
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I didn't think tufftriding was a building process, more of a surface hardening process. Does anyone chrome the cranks anymore ? A different crank might be better at this point.
Cutlassefi has the best approach to measuring. I precision ground dowel pin can work to measure the curved bearing shells if kept clean and straight in the bearing shell. Be sure to measure the dowel pin.
Ralph
Cutlassefi has the best approach to measuring. I precision ground dowel pin can work to measure the curved bearing shells if kept clean and straight in the bearing shell. Be sure to measure the dowel pin.
Ralph
December 26th, 2017, 05:13 PM
#13
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Imo it’s the only way to do it. I’ve seen plastigage be off by almost a full .001 before and most dial bore gauges will dig into the bearing more than you think.The only clearance that concerns me is the thrust. .0046 seems excessive when compared to the rest.
December 26th, 2017, 05:41 PM
#14
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I think your way is more time consuming, but also the most accurate. There is no way to know if the bearings are conforming to the bore in a perfectly round shape for measuring purposes.
Dial bore gages vary due to the "centering feet" and measuring probe diameter/radius and pressure. Bearings are soft and can be gouged. "Snap gauges" (telescoping gauges) are less accurate than a dial bore gauge.
As a general reference......... blonde and redhead hairs are generally .003", and brunettes are .004". Bearing clearance tolerances area lot less.
...........just my two cents worth on the topic.
December 26th, 2017, 08:12 PM
#15
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Main bores
1. 3.1886” 2. 3.1886” 3. 3.1890” 4. 3.1892” 5. 3.1892”
Main journals
1. 2.9883” 2. 2.9886” 3. 2.9885” 4. 2.9887” 5. 2.989”
Upper Main Bearings Shells
1. .0982” 2. .0984 3. 0983” 4. .0984” 5. .0977”
Lower Main Bearing Shells
1. .0985” 2. .0983” 3. .0982” 4. .0985” 5. .0978”
Clearance
1. .0036” 2. .0033” 3. .004” 4. .0036” 5. .0047”
1. 3.1886” 2. 3.1886” 3. 3.1890” 4. 3.1892” 5. 3.1892”
Main journals
1. 2.9883” 2. 2.9886” 3. 2.9885” 4. 2.9887” 5. 2.989”
Upper Main Bearings Shells
1. .0982” 2. .0984 3. 0983” 4. .0984” 5. .0977”
Lower Main Bearing Shells
1. .0985” 2. .0983” 3. .0982” 4. .0985” 5. .0978”
Clearance
1. .0036” 2. .0033” 3. .004” 4. .0036” 5. .0047”
Last edited by VinMichael; December 26th, 2017 at 09:53 PM.
December 26th, 2017, 08:18 PM
#16
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I measured the main bores, ball miked the bearing shells, then miked the main jouranals.
I typo’d the #5 clearance in the OP by around .001. And it turns out the bore gauge may have been digging into the bearings after all.
Sorry, I didn’t mention, this is a 455. I forgot there are other varieties of BBOs
I typo’d the #5 clearance in the OP by around .001. And it turns out the bore gauge may have been digging into the bearings after all.
Sorry, I didn’t mention, this is a 455. I forgot there are other varieties of BBOs
Last edited by VinMichael; December 26th, 2017 at 08:28 PM.
December 27th, 2017, 05:08 AM
#17
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I measured the main bores, ball miked the bearing shells, then miked the main jouranals.
I typo’d the #5 clearance in the OP by around .001. And it turns out the bore gauge may have been digging into the bearings after all.
Sorry, I didn’t mention, this is a 455. I forgot there are other varieties of BBOs
I typo’d the #5 clearance in the OP by around .001. And it turns out the bore gauge may have been digging into the bearings after all.
Sorry, I didn’t mention, this is a 455. I forgot there are other varieties of BBOs
Run it you’re fine. Just use a good 20W-50.
January 21st, 2018, 01:42 PM
#18
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Happy Sunday. I got around to measuring my rod clearances. They seem to be on the tighter side.
Just wondering if this will work, or if I need to take some material off the backs of the shells to get closer to .002”
Thank you
Just wondering if this will work, or if I need to take some material off the backs of the shells to get closer to .002”
Thank you
1. Rod bore 2.6243” upper bearing .0668” lower .0666” Rod journal 2.4891” clearance .0018”
2. Rod bore 2.6245” upper bearing .0668” lower .0668” Rod journal 2.4891” clearance .0018”
3. Rod bore 2.6240” upper bearing .0666” lower .0667” Rod journal 2.4893” clearance .0015”
4. Rod bore 2.6240” upper bearing .0666” lower .0666” Rod journal 2.4893” clearance .0015”
5. Rod bore 2.6242” upper bearing .0667” lower .0667” Rod journal 2.4891” clearance .0017”
6. Rod bore 2.6243” upper bearing .0667” lower .0667” Rod journal 2.4891” clearance .0018”
7. Rod bore 2.6241” upper bearing .0666” lower .0666” Rod journal 2.4893” clearance .0016”
8. Rod bore 2.6244” upper bearing .0668” lower .0667” Rod journal 2.4893” clearance .0016”
Last edited by VinMichael; January 21st, 2018 at 01:44 PM.
January 21st, 2018, 02:16 PM
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January 21st, 2018, 06:41 PM
#22
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Lets say I've got a main housing bore that should be finished honed to 2.937-2.938, I finish the bore to 2.9375 measured with a calibrated Sunnen dial bore gauge tenth reader, I measure the crank journal, then measure bearing housing bore and come up with .0025 clearance and I want .0027, I'am going to sand the back of the bearings halves to get to .0027. It seems the OP has a big variance in his housing bores.
March 24th, 2018, 12:06 PM
#23
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Circling back, I’m listing below the clearances I ended up with. My last question how to setup my M22F pump. OE or the purple spring? I’m going to run a small bead with a MIG welder on the pickup once the angle is determined. Oil pan is stock capacity. Non-Torandado pan
Running 20w-50
Mains
1. .0036” 2. .0033” 3. .004” 4. .0036” 5. .0047”
Rods
1. .0021” 2. .0022” 3. .0020” 4. .0020” 5. .0021” 6. .0021” 7. .0021” 8. .0021”
Rod side clearance
1-2. .015” 3-4. .013” 5-6. .009” 7-8. .009”
Thrust
.009”
Thanks as always for all of your opinions
Running 20w-50
Mains
1. .0036” 2. .0033” 3. .004” 4. .0036” 5. .0047”
Rods
1. .0021” 2. .0022” 3. .0020” 4. .0020” 5. .0021” 6. .0021” 7. .0021” 8. .0021”
Rod side clearance
1-2. .015” 3-4. .013” 5-6. .009” 7-8. .009”
Thrust
.009”
Thanks as always for all of your opinions
Last edited by VinMichael; March 24th, 2018 at 12:28 PM.
March 24th, 2018, 08:04 PM
#29
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https://www.tapatalk.com/groups/real...t2325-s20.html
If you do go with what Trovato says in his book, be sure you also use his recommended rod side clearance. He runs loose bearing clearances and tight side clearances for a reason.
If you do go with what Trovato says in his book, be sure you also use his recommended rod side clearance. He runs loose bearing clearances and tight side clearances for a reason.
March 25th, 2018, 04:59 AM
#30
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https://www.tapatalk.com/groups/real...t2325-s20.html
If you do go with what Trovato says in his book, be sure you also use his recommended rod side clearance. He runs loose bearing clearances and tight side clearances for a reason.
If you do go with what Trovato says in his book, be sure you also use his recommended rod side clearance. He runs loose bearing clearances and tight side clearances for a reason.
For the record some here have contended that I have it out for Bill, I don’t. But what I’ve said from the start is go to any track on any given weekend and you’ll see lots of guys making great power and being competitive. You dont NEED to be or follow Bill Travato to do that.
Last edited by cutlassefi; March 25th, 2018 at 05:06 AM.
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