LT1 Low Oil Pressure at Hot Idle Fix!!!
01-26-2018, 03:13 AM
#1
LT1 Low Oil Pressure at Hot Idle Fix!!! 
This 140* groove on the upper main bearings is the Key to solving the issue of low oil pressure at hot idle!!! SO Anyone have part numbers for these SBC / LT1 style main bearings??? Then Sticky the info... My 355 LT1 suffers from it & I want to use these when I go 383 with it!!!
01-27-2018, 04:50 PM
#3
So it restricts oil flow compared to a 180* groove and gives you the pressure you want to see....?
No problem with my warm idle. Build the new motor with a purpose in mind and size things accordingly with appropriate oil viscosity.
No problem with my warm idle. Build the new motor with a purpose in mind and size things accordingly with appropriate oil viscosity.
01-28-2018, 01:18 AM
#4
Provided that a Gen1, 5.7 Liter, SBC takes the same bearings as the LT1/4, then the Clevite part number is MS-804P.
http://www.speedzoneweb.com/clevite-.../i-463393.aspx
KW
http://www.speedzoneweb.com/clevite-.../i-463393.aspx
KW
01-28-2018, 07:20 PM
#5
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Now I'm just a small time 'wrencher'. BUT, from what I've found with low oil pres at operational temps is more of the horrible tolerance of the cam bearings and or their journals.
I'll go out on a limb and say that EVERY V8 (and even some 4cyl/6cyl Iron Jeep blocks) that I've pulled a cam and popped the bearings out had just terrible contact/wear patterns.
When you get the block apart, look at the front 'boss' where the cam journals were machined in.
Is it centered in that boss/raised casting, or is it a bit off to one side. And does it look the same from front to rear?
I've talked to a few engine builders about core shift and how prevalent/common that problem is with the casting processes. In addition to the inherent balancing issues of a V8 that the last 3 Chevy V8's I had pulled apart 4,5,7 rod bearings with poor oiling evidence. Was even told that by a local crank-shaft place here.
I'm in the process of building up a Caddy 500 and wondered if I should save up and have their journals measured and bored if necessary. It's just that the thicker bearings are fairly expensive AND, trying to find a competent machinist to do it correctly.. (THEY ALL say that they can do it, but will they stand behind their work?)
The bearings that i would like to get are sold by Cad500parts.com that are made just for them and are fully grooved and cost about 100.00. I just don't want to build a 500+ci motor, break it in, and have it idle with only 20-30psi at op temps in the HOT Memphis summer. (yes, I also know about the 10psi/1000rpms rule of thumb)
SO with all that, if you have the block all apart, take some time out and have the cam journals measured just for the added peace of mind.
Also, ask if the 'installers' bearing installation tool is all worn out, might not install as square as it should..(?)
Remember, they "hammer" them in.
Just sayin.. Not trying to start some arguments.
E
I'll go out on a limb and say that EVERY V8 (and even some 4cyl/6cyl Iron Jeep blocks) that I've pulled a cam and popped the bearings out had just terrible contact/wear patterns.
When you get the block apart, look at the front 'boss' where the cam journals were machined in.
Is it centered in that boss/raised casting, or is it a bit off to one side. And does it look the same from front to rear?
I've talked to a few engine builders about core shift and how prevalent/common that problem is with the casting processes. In addition to the inherent balancing issues of a V8 that the last 3 Chevy V8's I had pulled apart 4,5,7 rod bearings with poor oiling evidence. Was even told that by a local crank-shaft place here.
I'm in the process of building up a Caddy 500 and wondered if I should save up and have their journals measured and bored if necessary. It's just that the thicker bearings are fairly expensive AND, trying to find a competent machinist to do it correctly.. (THEY ALL say that they can do it, but will they stand behind their work?)
The bearings that i would like to get are sold by Cad500parts.com that are made just for them and are fully grooved and cost about 100.00. I just don't want to build a 500+ci motor, break it in, and have it idle with only 20-30psi at op temps in the HOT Memphis summer. (yes, I also know about the 10psi/1000rpms rule of thumb)
SO with all that, if you have the block all apart, take some time out and have the cam journals measured just for the added peace of mind.
Also, ask if the 'installers' bearing installation tool is all worn out, might not install as square as it should..(?)
Remember, they "hammer" them in.
Just sayin.. Not trying to start some arguments.
E
Last edited by Rockosocko; 01-28-2018 at 07:27 PM.
02-01-2018, 04:35 AM
#6
Im workin 12hr days so I dont check things as often as I used to...
The explanation under the bearings in the link KW provided explains it a little better than I can & the rticles I found were on Super Chevy & Grumpys Garage or somethin like that...
Even though My stock crank was polished the bearing tolerances were still within spec!!! But I dont like havin a gauge that Hovers at 0 oil pressure with 10w30 or 10 or 15w40!!! The 15w50 helped the most but it spun a rod bearing... And this wasnt a Stock run of the mill rebuild... I upgraded to Manley Hbeam 6in rods & Mahle forged flat tops because I was intending to beat on it a LiL
All bearings were new including the coated cam bearings... You could spin the motor over with 1 finger before the heads were installed... Yeah it ended up with a Fbody cam & iron heads but it ran Great before the rod bearing spun... This go round itll get Even More new parts to make it a 383 with Dart Pro 1 180cc heads lightly ported & prolly 2.05 intake valves... The cam will be a custom TQ cam for daily driver duty because this is in My Ext Cab S10 solid axle swapped truck LoL This go round its also gettin a 4L80E & 4.56 gears to spin the 35s
Funny thing the Cheap Vortec 4.3 I built after has Great Oil Pressure with the Same Stock Volume High Pressure pump & 0w30 Mobil 1... I switched after break in & its rightvat the same oil pressure hot or cold... The LT1 is Notorius for Livin on Low Oil Pressure & all I want is 20psi at Idle not 0 LoL
I know how to build motors Ive done several in My 45yrs on this planet lol
The explanation under the bearings in the link KW provided explains it a little better than I can & the rticles I found were on Super Chevy & Grumpys Garage or somethin like that...
Even though My stock crank was polished the bearing tolerances were still within spec!!! But I dont like havin a gauge that Hovers at 0 oil pressure with 10w30 or 10 or 15w40!!! The 15w50 helped the most but it spun a rod bearing... And this wasnt a Stock run of the mill rebuild... I upgraded to Manley Hbeam 6in rods & Mahle forged flat tops because I was intending to beat on it a LiL
All bearings were new including the coated cam bearings... You could spin the motor over with 1 finger before the heads were installed... Yeah it ended up with a Fbody cam & iron heads but it ran Great before the rod bearing spun... This go round itll get Even More new parts to make it a 383 with Dart Pro 1 180cc heads lightly ported & prolly 2.05 intake valves... The cam will be a custom TQ cam for daily driver duty because this is in My Ext Cab S10 solid axle swapped truck LoL This go round its also gettin a 4L80E & 4.56 gears to spin the 35s Funny thing the Cheap Vortec 4.3 I built after has Great Oil Pressure with the Same Stock Volume High Pressure pump & 0w30 Mobil 1... I switched after break in & its rightvat the same oil pressure hot or cold... The LT1 is Notorius for Livin on Low Oil Pressure & all I want is 20psi at Idle not 0 LoL
I know how to build motors Ive done several in My 45yrs on this planet lol
02-01-2018, 11:05 PM
#7
Now I'm just a small time 'wrencher'. BUT, from what I've found with low oil pres at operational temps is more of the horrible tolerance of the cam bearings and or their journals.
I'll go out on a limb and say that EVERY V8 (and even some 4cyl/6cyl Iron Jeep blocks) that I've pulled a cam and popped the bearings out had just terrible contact/wear patterns.
When you get the block apart, look at the front 'boss' where the cam journals were machined in.
Is it centered in that boss/raised casting, or is it a bit off to one side. And does it look the same from front to rear?
I've talked to a few engine builders about core shift and how prevalent/common that problem is with the casting processes. In addition to the inherent balancing issues of a V8 that the last 3 Chevy V8's I had pulled apart 4,5,7 rod bearings with poor oiling evidence. Was even told that by a local crank-shaft place here.
I'm in the process of building up a Caddy 500 and wondered if I should save up and have their journals measured and bored if necessary. It's just that the thicker bearings are fairly expensive AND, trying to find a competent machinist to do it correctly.. (THEY ALL say that they can do it, but will they stand behind their work?)
The bearings that i would like to get are sold by Cad500parts.com that are made just for them and are fully grooved and cost about 100.00. I just don't want to build a 500+ci motor, break it in, and have it idle with only 20-30psi at op temps in the HOT Memphis summer. (yes, I also know about the 10psi/1000rpms rule of thumb)
SO with all that, if you have the block all apart, take some time out and have the cam journals measured just for the added peace of mind.
Also, ask if the 'installers' bearing installation tool is all worn out, might not install as square as it should..(?)
Remember, they "hammer" them in.
Just sayin.. Not trying to start some arguments.
E
I'll go out on a limb and say that EVERY V8 (and even some 4cyl/6cyl Iron Jeep blocks) that I've pulled a cam and popped the bearings out had just terrible contact/wear patterns.
When you get the block apart, look at the front 'boss' where the cam journals were machined in.
Is it centered in that boss/raised casting, or is it a bit off to one side. And does it look the same from front to rear?
I've talked to a few engine builders about core shift and how prevalent/common that problem is with the casting processes. In addition to the inherent balancing issues of a V8 that the last 3 Chevy V8's I had pulled apart 4,5,7 rod bearings with poor oiling evidence. Was even told that by a local crank-shaft place here.
I'm in the process of building up a Caddy 500 and wondered if I should save up and have their journals measured and bored if necessary. It's just that the thicker bearings are fairly expensive AND, trying to find a competent machinist to do it correctly.. (THEY ALL say that they can do it, but will they stand behind their work?)
The bearings that i would like to get are sold by Cad500parts.com that are made just for them and are fully grooved and cost about 100.00. I just don't want to build a 500+ci motor, break it in, and have it idle with only 20-30psi at op temps in the HOT Memphis summer. (yes, I also know about the 10psi/1000rpms rule of thumb)
SO with all that, if you have the block all apart, take some time out and have the cam journals measured just for the added peace of mind.
Also, ask if the 'installers' bearing installation tool is all worn out, might not install as square as it should..(?)
Remember, they "hammer" them in.
Just sayin.. Not trying to start some arguments.
E
i'm a "lite wrencher" Junk yard scrounger
and can say low oil pressure at idel has to do more with cam journel clearances then main or rod bearing clearanace IMO
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02-13-2018, 12:43 AM
#8
Ghost I would say that about pretty much Any motor Except the LT1 gen II... My 355 was all the good **** & yeah it was a stock Fbody cam but it was a Low Milage motor I just wanted New 6in rods & lucked into some Mahle forged flat tops that were .030 over... The motor really only needed the Glaze Busted & Rebuilt!!! But over the years Ive noticed More than Just Me sayin My LT1 has Low Oil Pressure at Hot Idle... I will get the bearings as pictured when I take it to a 383 and add a better TQ cam because the LT1 is in My 4x4 SASd S10 ext cab
