Main bearing clearences

[Malthael]

So I am putting together my 5.7 2009+ when I measured the crank journals the mains were at the smallest allowable tolerance. Now I was installing ARP main studs so I had the block align honed and bought standard bearings, now since I didn't have a dial bore gauge I used plastigauge which showed .001 of clearence on all the mains. This has me concerned the crank still rotates freely, but I'm going to have around 11.3:1 compression so 0.8 higher than factory and plan on shifting at 6000 rpm maybe 5900 rpm, with a BTR stage 2 cam, was wondering if getting different main bearings would be the smart move here? Like -.001 undersize(oversized for more clearance) to increase my clearence to .002. my main concern is spinning a main bearing the first time I hit 6000rpm I am thinking of buying these bearings CLE-MS2220HX to increase my oil clearence.

 

[work truck ram]

Wear and machining is going to increase the gap. The only way the gap is too tight would be "under sized" bearings, oversized journal/caps. Under sized bearings refers to the journal undersized diameter. Undersized (journal) bearings are thicker to decrease space. Are you sure you had all of the oil cleaned out of there when you gauged it?

If you are running stock diameters or used stock parts it will not be too tight with stock bearings. Plastigauge is not that accurate. If you can still spin with a wrench it isn't too tight. Sloppy clearance worked on old, pre gen 2, race motors but not on new motors that you don't plan to tear down each season.

 

[Malthael]

Yes I wiped both the bearing surface the cap the block and the crank down with acetone before I gauged it. Is it worth it to spend the $366 on the dial bore gauge to check the clearences,. Last thing I need is to find out the hard way that it is to tight.

 

[Wild one]

Yes I wiped both the bearing surface the cap the block and the crank down with acetone before I gauged it. Is it worth it to spend the $366 on the dial bore gauge to check the clearences,. Last thing I need is to find out the hard way that it is to tight.

Buy the dial bore guage,and measure it properly using it and a good micrometer. Plasti gauge is okay on a junkyard build that you don't care about,but shouldn't be used on a good build. That cam should make power to at least 6400,you're definitely leaving power on the table shifting it at 5900

 

[Malthael]

Buy the dial bore guage,and measure it properly using it and a good micrometer. Plasti gauge is okay on a junkyard build that you don't care about,but shouldn't be used on a good build. That cam should make power to at least 6400,you're definitely leaving power on the table shifting it at 5900

I know I'm leaving power on the table but I'm using the stock connecting rods and really don't need it to spin to 6400 I'm okay with 10 horsepower on the table. I ended up using my t gauges and micrometer came out to .0013 on the mains but I'm getting different bearings so the clearence is closer to .0023 still checking the rods journals

 

[Wild one]

I know I'm leaving power on the table but I'm using the stock connecting rods and really don't need it to spin to 6400 I'm okay with 10 horsepower on the table. I ended up using my t gauges and micrometer came out to .0013 on the mains but I'm getting different bearings so the clearence is closer to .0023 still checking the rods journals

I spun the stock bottem end on my 5.7 to 6600 for 10 years and had 700+ nitrous dragstrip passes under it's belt when i sold the truck,and it still hot idled at 51 psi and carried 78/80 psi at it's shift points,and still pumped 218 psi on all 8 holes,last thing i ever worried about was the bottem end.There's quite a few guys with bigger cams then i had spinning their stock bottem end 5.7 to 7,000+ rpm. I even know of a couple guys spinning a stock bottem end 5.7 to 7200 rpm with a big cam

 

[Malthael]

I spun the stock bottem end on my 5.7 to 6600 for 10 years and had 700+ nitrous dragstrip passes under it's belt when i sold the truck,and it still hot idled at 51 psi and carried 78/80 psi at it's shift points,and still pumped 218 psi on all 8 holes,last thing i ever worried about was the bottem end.There's quite a few guys with bigger cams then i had spinning their stock bottem end 5.7 to 7,000+ rpm. I even know of a couple guys spinning a stock bottem end 5.7 to 7200 rpm with a big cam

Was that with the stock Pistons or lighter forged pistons?

 

[Malthael]

Was that with the stock Pistons or lighter forged pistons?

I find it extremely hard to believe that it hot idled at 51 psi with the stock pump when mine idled at 22psi hot unless you had an aftermarket pump or extremely thick oil

 

[Wild one]

I find it extremely hard to believe that it hot idled at 51 psi with the stock pump when mine idled at 22psi hot unless you had an aftermarket pump or extremely thick oil

Stock pump with 5W-30 Redline and the idle set at 750 rpm and dual remote filters. I never once touched the bottem end of the motor. The way it left the factory is the way it was
Turn the idle up to at least 750,even my bone stock 300 with 80,000 miles on it's 5.7 hot idles at 49 psi with the idle turned up to 750. Something was whacked with your 5.7 if your truck only idled with 22 psi,i'd guess either the pick-up screen was close to being plugged or the o-ring on the pick-up tube wasn't sealing properly,as i know of lots of 5.7's and not one of them idles with that low of oil pressure. Even with the 550/600 stock idle rpm,most of them still idle in the mid 30 or higher range even with 5W-20 in the crankcase

 

[Malthael]

Stock pump with 5W-30 Redline and the idle set at 750 rpm and dual remote filters. I never once touched the bottem end of the motor. The way it left the factory is the way it was
Turn the idle up to at least 750,even my bone stock 300 with 80,000 miles on it's 5.7 hot idles at 49 psi with the idle turned up to 750. Something was whacked with your 5.7 if your truck only idled with 22 psi,i'd guess either the pick-up screen was close to being plugged or the o-ring on the pick-up tube wasn't sealing properly,as i know of lots of 5.7's and not one of them idles with that low of oil pressure. Even with the 550/600 stock idle rpm,most of them still idle in the mid 30 or higher range even with 5W-20 in the crankcase

Yeah I just checked my rod bearing clearances and something from the factory was definitely different because I put standard bearings in it and the clearance is like .003 and they are standard bearings which is ridiculous way too lose it is a 2009 pretty bad year for the economy so it's got parts that shouldn't be on it like the axles I couldn't find an axle shaft for it got all different kinds and none of them were right. Was bought with 15,000miles.

 

[Malthael]

Yeah I just checked my rod bearing clearances and something from the factory was definitely different because I put standard bearings in it and the clearance is like .003 and they are standard bearings which is ridiculous way too lose it is a 2009 pretty bad year for the economy so it's got parts that shouldn't be on it like the axles I couldn't find an axle shaft for it got all different kinds and none of them were right. Was bought with 15,000miles.

Whenever I would floor it I'd hit 55psi of oil pressure hot

 

[Wild one]

Whenever I would floor it I'd hit 55psi of oil pressure hot

Even that's really low,it should be closer to 70 psi at the factory 5600 rpm shift points.
I'm guessing when it was originally assembled it got the + sized bearings then. They have a + and - factor to the bearings in regards to clearances,and it sounds like it might have got all + clearance bearings if it had that low of pressures from when it was basically new with only 15,000 miles on it.
Being a 2009 it should of still had the corporate AAM diffs under it,as they didn't switch over to the ZF diffs until 2011.

 

[Malthael]

Even that's really low,it should be closer to 70 psi at the factory 5600 rpm shift points.
I'm guessing when it was originally assembled it got the + sized bearings then. They have a + and - factor to the bearings in regards to clearances,and it sounds like it might have got all + clearance bearings if it had that low of pressures from when it was basically new with only 15,000 miles on it.
Being a 2009 it should of still had the corporate AAM diffs under it,as they didn't switch over to the ZF diffs until 2011.

Once I switched to 10w30 it was better had 50psi cold starts and 27-34psi idle but still low. But I do know why now with those bearings. My brother has an 2007 Aspen with the 5.7 he accidentally put to much oil in it cause in the oil to aerate and lost oil pressure when we changed the oil it had a bunch of metal in it and in the filter looked terrible that was 30,000 miles ago it has 264,000 miles on it, he always would use 10w30 once he crossed 200k but it still idles with 40+psi of oil pressure hot cold starts with 57psi in the summer

Anyway I have oversized bearings on the way to compensate for the increased clearence hopefully they get here before the 4th.

 

[Malthael]

Have you ever heard of mixing bearings like half and half one standard and one oversized or undersize to get the clearence you want?

 

[Wild one]

Have you ever heard of mixing bearings like half and half one standard and one oversized or undersize to get the clearence you want?

Yup,it's done all the time

 

[Malthael]

Im kinda in a tough spot right now i can't get oversized bi metal main bearings the only thing I can get is race bearings, but I'm not building a race car, and don't know what kind of longevity those will provide. Either run the race bearings with proper clearence or standard, was hoping to get 150,000+miles out of this engine, but from what I read the race bearings won't let that happen.

Edit: I think I'm just gonna say screw it run the tighter clearences and just pray if I ever had a boost I don't spin a main.

 

[Grams]

There’s WAY too much worry goin’ on in the world over oil pressures.’

“Pressure” …Itself…is not something that you need a high-order. Oil Pressure is only an “indication” that All areas of the engine ARE being Lubircated.

20 psi is as good as 50 psi as far as lubrication goes… the difference is onlyh a signal that “tight” clearances are non-existant in some area… It does Not mean that area is not being lubricated. In other words, higher oil Pressure isn’t what keeps parts separated “better”.

A brand-new-built engine with known tight-cleanances that makes 50 psi hot…. would worry me more than one with ordinary clearances making 20 psi when it was hot.

 

[Wild one]

Im kinda in a tough spot right now i can't get oversized bi metal main bearings the only thing I can get is race bearings, but I'm not building a race car, and don't know what kind of longevity those will provide. Either run the race bearings with proper clearence or standard, was hoping to get 150,000+miles out of this engine, but from what I read the race bearings won't let that happen.

Edit: I think I'm just gonna say screw it run the tighter clearences and just pray if I ever had a boost I don't spin a main.

Take the crank to your machinist and have him polish it.I'm kind of wondering why you didn't have the machine shop assemble the bottom end of the engine,when you had them align bore it. You spent money on ARP studs which are total overkill for what you're planning on doing,so why didn't you give the machinist a few more bucks and have it properly assembled by them.

 

[Malthael]

Not trying to be rude but I have that kind of money and they charged a crap ton of money with the hone over .010 deck cleanup align hone and rotating assembly rebalance, was already $2000 then the other shop for the heads which were milled .020" and valve job was $600. The reason I used arp hardware is so don't have to buy 10 sets of main bolts to test fit the crank the factory bolts are 1 time use, I'm not risking all this money on reusing hardware. Not to say didn't ask about them polishing it but they wanted $300 for it so I'm like no to much.

 

[Wild one]

Not trying to be rude but I have that kind of money and they charged a crap ton of money with the hone over .010 deck cleanup align hone and rotating assembly rebalance, was already $2000 then the other shop for the heads which were milled .020" and valve job was $600. The reason I used arp hardware is so don't have to buy 10 sets of main bolts to test fit the crank the factory bolts are 1 time use, I'm not risking all this money on reusing hardware. Not to say didn't ask about them polishing it but they wanted $300 for it so I'm like no to much.

Spend the 300 and have the crank polished.You're better off having a bit more clearance then not enough.Tight and she's gonna spin a bearing,then you're back to square 1 spending a pile of money to do it right.
You can always compensate for a crank with a bit looser clearances with a thicker oil,you can't compensate for a crank with clearances that are to tight.
Your call but i think you're crazy by not having the crank polished,and wanting to stick new bearings on a high milege crank