.0015" clearance on main and rod bearings
May 27, 2015, 08:16 PM
#1
.0015" clearance on main and rod bearings
As the title states. I measured both main and rod with a plastigauge. I got .0015" throughout the entire motor. Someone said this was fine and another said that's too tight for the power I want (eventually want to reach 600hp). I don't want to end up running these tight of a clearance if it means I have to rip it back apart and do it again.
If it relates:
-Bearings are King Racing XP
-Crank is K1 Technologies
-Rods are Manley Turbo Tuff
If it relates:
-Bearings are King Racing XP
-Crank is K1 Technologies
-Rods are Manley Turbo Tuff
May 27, 2015, 08:33 PM
#2
That's what stock calls for. I would use it! I don't like "loose" bearing clearances. The rod should never get hot enough to close that gap compared to a stock motor to cause an issue.
May 30, 2015, 05:42 PM
#4
I run 20w50 with stock clearances. 60k miles and no bearing issues. The head looked great when I installed cams there was no abnormal wear. The motor had 40k on 20w50 and 100k miles total. I also live in a climate that gets down to single digits in the winter and I never ran thinner oil in the winter. I use AMSOIL ARO Premium Protection 20w50. Stock clearances on my 2.0 and on my 2.4. I have 10k or so on the 2.4 and rev it to 8k regularly and have accidentally hit 8800 no problem. No oil squirters or balance shafts. Stock motor still had balance shafts and squirters.
May 30, 2015, 06:28 PM
#6
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Normally, looser clearances are recommended if the motor is going to be routinely beat on at high power levels...
Also, in regards to the oil; take what other people say with a grain of salt. You need an oil pressure gauge to make sure you are getting the pressure/flow you need. Too thick of an oil and your PSI goes up the flow goes down... You want just enough pressure to keep consistent flow.
I think in the past when I built a motor for my first time, it was recommended, at minimum to have 10psi for every 1k rpms. So at 8k rpms, you need to have ~80psi of oil pressure. Removing the balances shafts, and oil cooler will allow for more pressure but remember, too much can be bad as that is restrict flow...
Think of it as a water hose. You cover half of the opening with your thumb and the pressure increases but less water comes out(less flow)... Take your thumb off and it flows free but with less pressure. Need to get a happy median. I don't think you're stupid or don't know this, but I have no idea what you do/don't know so just trying to help out as best as I can.
If you really want to learn about oil, I suggest giving this page a read:
http://www.bobistheoilguy.com/motor-oil-101/
It's long (that's what she said) but it's worth the read.
Also, in regards to the oil; take what other people say with a grain of salt. You need an oil pressure gauge to make sure you are getting the pressure/flow you need. Too thick of an oil and your PSI goes up the flow goes down... You want just enough pressure to keep consistent flow.
I think in the past when I built a motor for my first time, it was recommended, at minimum to have 10psi for every 1k rpms. So at 8k rpms, you need to have ~80psi of oil pressure. Removing the balances shafts, and oil cooler will allow for more pressure but remember, too much can be bad as that is restrict flow...
Think of it as a water hose. You cover half of the opening with your thumb and the pressure increases but less water comes out(less flow)... Take your thumb off and it flows free but with less pressure. Need to get a happy median. I don't think you're stupid or don't know this, but I have no idea what you do/don't know so just trying to help out as best as I can.
If you really want to learn about oil, I suggest giving this page a read:
http://www.bobistheoilguy.com/motor-oil-101/
It's long (that's what she said) but it's worth the read.
Last edited by stiffdogg06; May 30, 2015 at 06:33 PM.
May 31, 2015, 08:48 AM
#7
The difference is that your example changes the size of the opening to change flow. In a static environment more pressure through an opening ALWAYS means more flow. The only time it is a problem is when the desired flow is larger than the volume that can be delivered. At that point you must make a bigger galley. So if you are porting the oil passages then you will have less pressure at the same volume or more volume at the same pressure.
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Jun 1, 2015, 04:40 PM
#8
Except you are changing the size of the opening.
Remove balance shaft = "smaller hole"
Kiggly HLA = "smaller hole"
Looser bearing clearances = "bigger hole"
I've done looser clearances with thicker oil.
I've done smaller clearances with thinner oil.
While thinner oil and tighter clearances sounds great on paper (improved efficiency), if you screw up and go too tight, bye bye motor when things try to weld to each other with little warning as pressure will be "good" (if not high).
Too loose and you can kill a motor too, but it's not usually without warning and with parts welding together. You can also see it in low pressure as the damage is happening over time.
Now...screw up the balance between rod bearing and main bearing clearance and you can weld stuff together even with loose tolerances.
Remove balance shaft = "smaller hole"
Kiggly HLA = "smaller hole"
Looser bearing clearances = "bigger hole"
I've done looser clearances with thicker oil.
I've done smaller clearances with thinner oil.
While thinner oil and tighter clearances sounds great on paper (improved efficiency), if you screw up and go too tight, bye bye motor when things try to weld to each other with little warning as pressure will be "good" (if not high).
Too loose and you can kill a motor too, but it's not usually without warning and with parts welding together. You can also see it in low pressure as the damage is happening over time.
Now...screw up the balance between rod bearing and main bearing clearance and you can weld stuff together even with loose tolerances.
Jun 2, 2015, 02:26 PM
#10
I'm running closer to .0025, but all I do is beat on it and it makes a little under 700hp. Oil pressure has stayed constant and seems to be fine with a few thousand miles on it so far. I wanted to run a tad tighter, standard bearings had my clearances a little over 3 thousandths, I tightened them up with oversized bearings. I would highly recommend finding a dial bore gage and a micrometer though, as I just don't care for plastigages, they could vary .003-.005 imo.
Jun 7, 2015, 08:17 AM
#12
Just to clarify, you have 167,000 miles on your built motor? How has it held up as far as compression? Most people claim that a built motor will wear out much faster due to the forged pistons and wider clearances.
Jun 8, 2015, 06:02 PM
#13
I will take compression test soon to let you know.
Forged pistions will need a better PTW clearance. if using wiseco's even more.
My buddy was told every 30K he would need a rebuild, BS.
Sure, if you want to change bearings all the time, why not.
Jun 8, 2015, 07:28 PM
#14
What you've heard, Its all BS.
I will take compression test soon to let you know.
Forged pistions will need a better PTW clearance. if using wiseco's even more.
My buddy was told every 30K he would need a rebuild, BS.
Sure, if you want to change bearings all the time, why not.
I will take compression test soon to let you know.
Forged pistions will need a better PTW clearance. if using wiseco's even more.
My buddy was told every 30K he would need a rebuild, BS.
Sure, if you want to change bearings all the time, why not.