Lq4 main bearing clearances
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Teching In
Joined: May 2025
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Lq4 main bearing clearances Hello I have a question for the experts I’m figuring out my main bearing clearances with plasti gauge the clearances for my 6.0 lq4 are between 0.008 and 0.0020 inches… mind you I have had the crank polished and I am building it for just street use the guy at the machine shop said it didn’t need a line hone only polishing the crank.
I am also using king racing bearings with the teflon coating so I don’t know if that is making a difference in the end result or not. Here’s the pn for the bearings “MB5013XP”
Plus the description says “King's advanced control measures hit a bull's-eye, maintaining wall thickness tolerances far tighter than their competitors--an amazing +/- .0001 in.” So I don’t know if I have 0.0001in of play, wether it takes .0001 away or adds .0001
if you look at attachments the videos maybe can help
first main cap it seems pretty dead on .0015 in
second main cap seems pretty much the same on .0015 in aswell
the third main cap is were it’s almost .0015 in or a lil more than the measurement on the paper
the 4th main cap seems pretty dead on too on .0015in
the 5th one seems the same dead on .0015
im a lil worried about the 3rd one but also wondering if the .0015 is a good clearance for building a engine I’m going to abuse every now and then hoping it’s not too tight and my oil pressure is through the roof
I am also using king racing bearings with the teflon coating so I don’t know if that is making a difference in the end result or not. Here’s the pn for the bearings “MB5013XP”
Plus the description says “King's advanced control measures hit a bull's-eye, maintaining wall thickness tolerances far tighter than their competitors--an amazing +/- .0001 in.” So I don’t know if I have 0.0001in of play, wether it takes .0001 away or adds .0001
if you look at attachments the videos maybe can help
first main cap it seems pretty dead on .0015 in
second main cap seems pretty much the same on .0015 in aswell
the third main cap is were it’s almost .0015 in or a lil more than the measurement on the paper
the 4th main cap seems pretty dead on too on .0015in
the 5th one seems the same dead on .0015
im a lil worried about the 3rd one but also wondering if the .0015 is a good clearance for building a engine I’m going to abuse every now and then hoping it’s not too tight and my oil pressure is through the roof
Last edited by S0lar217; Oct 25, 2025 at 10:47 PM.
Plastiguage always reads on the tighter side. You’ve got .018ish on the caps, other than #3….according to Plastiguage. I’d bet it’s close to .002 with my dial bore gauge. I’d go ahead and put the crank in and torque it, and see if it spins freely. While the crank is torqued, go ahead and see how thrust looks. Have you checked the rods yet? If you have and they are similar, I’d go ahead and take the crank back out of the block and final clean it all for final assembly. You’re fine with the crank at least, as long as it spins easily, and thrust is ok.
Plastiguage is better than a guess, but very innacurate. Having said that, I’m not surprised that you’re seeing inconsistency with King bearings. I was Kings biggest fan for a long time, but I’ve seen inconsistencies in the past few years with their stuff, along with other top tier builders I talk with. If your planning on future builds yourself, I’d recommend spending a couple grand on a couple-few dial bore gauges and other building tools to make this job both, more enjoyable, and quicker, and also far more accurate. Accuracy gives you a great feeling in knowing that you’re correct, and you don’t have to reach out with questions for others.
Plastiguage is better than a guess, but very innacurate. Having said that, I’m not surprised that you’re seeing inconsistency with King bearings. I was Kings biggest fan for a long time, but I’ve seen inconsistencies in the past few years with their stuff, along with other top tier builders I talk with. If your planning on future builds yourself, I’d recommend spending a couple grand on a couple-few dial bore gauges and other building tools to make this job both, more enjoyable, and quicker, and also far more accurate. Accuracy gives you a great feeling in knowing that you’re correct, and you don’t have to reach out with questions for others.
