Main bearing clearance ?
Main bearing clearance ? I have a tsp 408 stroker kit. I installed it with there bearings and got reading between .017 and .020. So assuming using plasti gauge the average is between them. Is that good or to tight? This will be n/a no forced induction or anything and street driven no track except maybe once or twice. Any in put would be great.
Clearances are generally around .0022 not .020. If you are seeing .020 then either something is wrong or the measurement itself is wrong
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I have a tsp 408 stroker kit. I installed it with there bearings and got reading between .017 and .020. So assuming using plasti gauge the average is between them. Is that good or to tight? This will be n/a no forced induction or anything and street driven no track except maybe once or twice. Any in put would be great.
The main housing bore spec has about .0005” tolerance from the low to the high side, so that alone can skew the bearing clearance without anything being “wrong”. If you have STD bearings, you could mix in half a set of X bearings to gain about .0005” clearance. You could also have your machine shop align hone the block a little more, but that might he the more costly option.
If you’re being honest about the use, then it’s probably ok to run that. Most people will say, “oh I only plan to run 10psi or make 500whp” and then end up with twice that, so personally I would prefer to see a little more clearance.
The main housing bore spec has about .0005” tolerance from the low to the high side, so that alone can skew the bearing clearance without anything being “wrong”. If you have STD bearings, you could mix in half a set of X bearings to gain about .0005” clearance. You could also have your machine shop align hone the block a little more, but that might he the more costly option.
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A good place to start is by using a Bore dial gauge, not plasti gauge. That will at least give you a GOOD solid starting point. As KCS already said, you may need to order a set of x bearings and use only the halves of each set to slightly
increase clearance, if that's what you want. You may find that after using a decent Bore dial gauge, your clearances are within spec. That and the Torque wrench were one of my two best investments for tools lol. Good luck.
increase clearance, if that's what you want. You may find that after using a decent Bore dial gauge, your clearances are within spec. That and the Torque wrench were one of my two best investments for tools lol. Good luck.
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Verdad Gallardo The thing with clearances is that you can ask 5 people and get 5 different answers. Most prefessional builders will shoot for a range and not necessarily a perfect number. What you’re getting will probably be ok, if itnwere measured with a dial bore gauge. With plastigaue, it’s not as accurate so you could actually he a little looser or toghter. As a general rule of thumb, its hetter to be too loose than too tight.
Those numbers are good for an aluminum build. I’ve seen as low as .0014” for aluminum builds. I like .0020 to .0025 for iron blocks. But as KCS said above, lots of folks want different things.
Thanks guys i went out today and ordered a micrometer and feelers. I bolted the mains down and torqued them as close to perfect as possible and cleaned all the bearings from there greasiness and tomorrow i will use the hates to see the exact clearnce of the bearings and crank. So let's hope they are closer then plastigauge. Tsp told me around .0020 and .0025 ish somewhere around there. And that my numbers Were a little to tight for there liking so I'm hoping plastigauge just sucked and they are pretty damn close to tsp specs. I will update you with anymore info tomorrow.
Launching!
Joined: Jan 2018
Posts: 283
Likes: 0
feeler gauge will be a struggle and inaccurate. feeler gauge wont show you bearing deformation indicating a good crush.
best tooling is outside micrometer and dial bore gauge. measure the crank with the mic and lock it. set the mic in vice, then but dial bore gauge in the mic and set it to 0. you want your bore gauge to say 0 measuring the gap between the mic tips.
torque up the rod or main cap to spec with the bearing. now put your dial bore gauge in the torqued up cap. you'll immediately see a gauge reading of +0.002-0.004" you will also see that the measurements directly up and down is less that the measurement diagonally just shy of horizontal. this shows that the bearing is deformed and out of round. if you see this you know you have a good bearing crush.
best tooling is outside micrometer and dial bore gauge. measure the crank with the mic and lock it. set the mic in vice, then but dial bore gauge in the mic and set it to 0. you want your bore gauge to say 0 measuring the gap between the mic tips.
torque up the rod or main cap to spec with the bearing. now put your dial bore gauge in the torqued up cap. you'll immediately see a gauge reading of +0.002-0.004" you will also see that the measurements directly up and down is less that the measurement diagonally just shy of horizontal. this shows that the bearing is deformed and out of round. if you see this you know you have a good bearing crush.
Teching In
Joined: Jul 2018
Posts: 4
Likes: 0
Main Clearance Help I'm new to this and I'm having trouble with my main clearances. Using plastigauge with a new 5.3L iron block, a new Lunati crankshaft (part # 70840001). Probably going to be a turbo build for mostly street with a target HP of ~400-500.
Anyway, I started with standard Clevite main bearings (ms-2199H) and got a clearance of 0.001. I swapped them for a set that was 0.001 undersized (ms-2199HX) and now I'm getting 0.0015 clearance.
Is this enough clearance for this build?
If not, what do I do to open it up a little? I can't find any 0.002 undersized bearings out there.
If I stick with 0.0015 clearance, what weight oil should I use?
Thanks
Anyway, I started with standard Clevite main bearings (ms-2199H) and got a clearance of 0.001. I swapped them for a set that was 0.001 undersized (ms-2199HX) and now I'm getting 0.0015 clearance.
Is this enough clearance for this build?
If not, what do I do to open it up a little? I can't find any 0.002 undersized bearings out there.
If I stick with 0.0015 clearance, what weight oil should I use?
Thanks
I'm new to this and I'm having trouble with my main clearances. Using plastigauge with a new 5.3L iron block, a new Lunati crankshaft (part # 70840001). Probably going to be a turbo build for mostly street with a target HP of ~400-500.
Anyway, I started with standard Clevite main bearings (ms-2199H) and got a clearance of 0.001. I swapped them for a set that was 0.001 undersized (ms-2199HX) and now I'm getting 0.0015 clearance.
Is this enough clearance for this build?
If not, what do I do to open it up a little? I can't find any 0.002 undersized bearings out there.
If I stick with 0.0015 clearance, what weight oil should I use?
Thanks
Anyway, I started with standard Clevite main bearings (ms-2199H) and got a clearance of 0.001. I swapped them for a set that was 0.001 undersized (ms-2199HX) and now I'm getting 0.0015 clearance.
Is this enough clearance for this build?
If not, what do I do to open it up a little? I can't find any 0.002 undersized bearings out there.
If I stick with 0.0015 clearance, what weight oil should I use?
Thanks
I'm new to this and I'm having trouble with my main clearances. Using plastigauge with a new 5.3L iron block, a new Lunati crankshaft (part # 70840001). Probably going to be a turbo build for mostly street with a target HP of ~400-500.
Anyway, I started with standard Clevite main bearings (ms-2199H) and got a clearance of 0.001. I swapped them for a set that was 0.001 undersized (ms-2199HX) and now I'm getting 0.0015 clearance.
Is this enough clearance for this build?
If not, what do I do to open it up a little? I can't find any 0.002 undersized bearings out there.
If I stick with 0.0015 clearance, what weight oil should I use?
Thanks
Anyway, I started with standard Clevite main bearings (ms-2199H) and got a clearance of 0.001. I swapped them for a set that was 0.001 undersized (ms-2199HX) and now I'm getting 0.0015 clearance.
Is this enough clearance for this build?
If not, what do I do to open it up a little? I can't find any 0.002 undersized bearings out there.
If I stick with 0.0015 clearance, what weight oil should I use?
Thanks
On The Tree
Joined: Oct 2004
Posts: 98
Likes: 11
From: in a large steel structure
here is a good video on the proper way to do bearing clearance... when I do this, I take my time... and zero my bore gage to each individual crank journal. I also double check my clearance with a set of "T" gages... say I'm shooting for .0025 clearance.If I get one bearing set at say, ,0023 and on at .0027 I'll start by swapping out the bearing sets.. to try to get .0025 nominal. sometimes is works... sometimes I have to swap upper and lower shells to split the dif... the only time I use plastic gage... is If im checking the engine for wear after I have run it for a while. no way would I use it for a new build.....last.... I have access to a gage lab at work...I bring my personal mic's and torque wrenches into work to get them calibrated. since I only build a recip. engine maybe once a year.. I usually get them calibrated before I use them. at work we cal the gages once every 3 months or if they get dropped... excessive? yes...but I think you guys would appreciate our attention to detail when you are aboard a 737 at 30,000 feet. 
https://www.bing.com/videos/search?q...1&&FORM=VRDGAR
https://www.bing.com/videos/search?q...1&&FORM=VRDGAR