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Old 03-09-2009, 02:00 AM   #1
blkwagon
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Default ACL Race bearing clearance questions

Today i went to assemble my short block and ran into a problem when checking the clearance for the rod bearings. I am using ACL race bearings and plastigauges to check for the clearances. All the clearance came out to .051mm which is right above the factory limit. After reading around i found the the "race" series bearings are .001" on the loose side over stock. Should i ditch the ACL and go pick up a set of oem so i can get it with in spec??This is going to be my daily driver and occasionally track and Auto X. Any input from people with experience would be great.
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Old 03-09-2009, 05:12 AM   #2
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have a machinist measure them. plastigauge isnt a very accurate way to check. and a little on the loose side is good, you dont want tight bearings!
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Old 03-09-2009, 07:37 AM   #3
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Stick with the ACL bearings if you read my reply on the spun bearings thread and use a good 10W 40 oil they will be fine,also seems people here have issues with Mobil 1,personally I have used Mobil 1 racing 4t 15W 50 oil in many high performance and race engines with no ill effects unlike say the cheaper grades of some in theory high quality oils such as Motul.
Castrol used to sponsor my rally car so I know that for instance they are only a marketing company,castrol oils are blended here in Australia by valvoline proibably the same in the US.
My oils came direct from the chemists and I learnt a lot from them as what I was supplied were exotic blends such as AH39/76 all lab spec development oils they did have their own labs for product development but manufacture is farmed out.Castrol syntec was one of the oils I tested and it's good stuff in the right grade for the application,10W30 is for granny's shopping trolley.
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Old 03-09-2009, 10:39 AM   #4
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ACL race bearings come in a couple of flavors, H and HX, the HX's are the oversized ones meaning they have more clearance. If you have HX then use H. 0.051mm is about 2 thou which is a little loose for a stock pump. I run 2 thou for rods, 1.5 thou mains.

If you have H's then they should be the same size as stock bearings
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Old 03-10-2009, 01:51 PM   #5
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My clearances were like half of what yours are so I would say that's probably not a good idea to assemble a new engine that far on the loose end. It doesn't have any room to spare. What is the advantage of the ACL bearings? I just used Topline bearings.
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Old 03-10-2009, 02:24 PM   #6
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Quote:
Originally Posted by mick_the_ginge View Post
ACL race bearings come in a couple of flavors, H and HX, the HX's are the oversized ones meaning they have more clearance. If you have HX then use H. 0.051mm is about 2 thou which is a little loose for a stock pump. I run 2 thou for rods, 1.5 thou mains.

If you have H's then they should be the same size as stock bearings
Mick i think hit it on the head, check which box you picked up you may not have the "h's"
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Old 03-10-2009, 04:28 PM   #7
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Topline bearings are more like the stock, ACL Duraglide or Clevite 77 bearings. ACL RACE bearings are different, much harder surface, tri-metal
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Old 03-10-2009, 04:46 PM   #8
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i will be getting ACL bearings, how do i know which ones to order? and i want the H correct?
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Old 03-10-2009, 04:49 PM   #9
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well i got my part numbers and they are the "H" bearings. Would OEM be slightly thicker?? The crank only has 11k on it and same with the block so i wouldn't think it would be worn out.
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Old 03-10-2009, 04:57 PM   #10
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Quote:
Originally Posted by seanathanq83 View Post
i will be getting ACL bearings, how do i know which ones to order? and i want the H correct?
http://www.aclperformance.com.au/us/...rings_crus.htm

Subaru EJ16, EJ18S, EJ20E, EJ20T, EJ22, EJ22T, EJ25, EJ25T

Rod bearings
4B8320H (for 48mm journal) (older crank)
4B8320HX

4B8296H (for 52mm journal)
4B8296HX

Main
5M8297H (Thrust in #3 pos) (Older cranks and cases)
5M8297HX

5M8309H (Thrust in #5 pos)
5M8309HX

H Standard oil clearance
HX +0.001" extra oil clearance

I felt like one of these because I had not see this little smile before.

Quote:
Originally Posted by blkwagon View Post
well i got my part numbers and they are the "H" bearings. Would OEM be slightly thicker?? The crank only has 11k on it and same with the block so i wouldn't think it would be worn out.
Some people manage to spin out bearings with 100miles. Unless you measure the crank/case you will have no idea of the real clearances. Stock bearings should be the same thickness as ACL "H".
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Old 03-10-2009, 05:14 PM   #11
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Quote:
Originally Posted by mick_the_ginge View Post

Some people manage to spin out bearings with 100miles. Unless you measure the crank/case you will have no idea of the real clearances. Stock bearings should be the same thickness as ACL "H".

well ill measure the crank...the motor never actually spun a bearing just had a cracked rigland. Ill try to measure it tonight after work and ill see.
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Old 03-10-2009, 05:47 PM   #12
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would there be any need for HX? i will be running a v8 207, and want to be able to rev to 8500-9k, would the H be fine?
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Old 03-10-2009, 06:20 PM   #13
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Quote:
Originally Posted by n2oiroc View Post
have a machinist measure them. plastigauge isnt a very accurate way to check. and a little on the loose side is good, you dont want tight bearings!
Wrong,
While using a bore gauge and a mic is a good way to check, plasti-gauge is absolutely an accepted method for measuring clearance(s) very accurately.
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Old 03-10-2009, 06:31 PM   #14
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Quote:
Originally Posted by Team Scream View Post
Wrong,
While using a bore gauge and a mic is a good way to check, plasti-gauge is absolutely an accepted method for measuring clearance(s) very accurately.
not so much, i mean i was taught to use it (plastigage) by a machinist. but i trust real tools.

http://www.carcraft.com/techfaq/116_...ter/index.html

im putting a stock shortblock together this week, using ACL bearings however. I will monitor room temp and mic/dial everything out as well as use plastigage and report my findings.
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Old 03-10-2009, 06:35 PM   #15
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Quote:
Originally Posted by Team Scream View Post
Wrong,
While using a bore gauge and a mic is a good way to check, plasti-gauge is absolutely an accepted method for measuring clearance(s) very accurately.
yea the guy who did my heads and my machining on my motor recommended me to use plasitgauge
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Old 03-10-2009, 07:33 PM   #16
mick_the_ginge
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Quote:
Originally Posted by seanathanq83 View Post
would there be any need for HX? i will be running a v8 207, and want to be able to rev to 8500-9k, would the H be fine?
That depends on what clearances you want to run. My last block used a mix of H, HX's and some polishing to get my desired clearances on rods and main. Sometimes you will get what you want with standard and a polish, sometimes you need to go with a bearing designed to provide more clearance.


Quote:
Originally Posted by blkwagon View Post
yea the guy who did my heads and my machining on my motor recommended me to use plasitgauge
The only problem with Plasitgauge is that it can be inaccurate if the crank or rod shifts when it's inplace. Any shift smears it out and makes the reading useless. When done right it can be as accurate as tooling. However their lies the problem, it's easy to screw it up.
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Old 03-10-2009, 07:38 PM   #17
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so mick for a good daily driver what would be the desired clearance for the mains and rods? It is a ej25 with eagle rods and cp 100mm pistons???
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Old 03-10-2009, 07:48 PM   #18
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Quote:
Originally Posted by blkwagon View Post
so mick for a good daily driver what would be the desired clearance for the mains and rods? It is a ej25 with eagle rods and cp 100mm pistons???
Power levels? Stock Oil pump? Reving to what?

Daily driver, stock pump, stock rev limit, I would do 1 thou mains and 1.2/1.5 thou rods.
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Old 03-10-2009, 08:04 PM   #19
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right now stock vf39 until i fix the 6 speed i have and maybe as big as dom III. but stock rev limit and stock pump. i've been reading bout moding the stock pump for more pressure but not sure if its a good idea for me or not.
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Old 03-10-2009, 08:36 PM   #20
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1 thou mains and 1.2/1.5 thou rods seems about right.

What do the other builder think?
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Old 03-10-2009, 09:57 PM   #21
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im going to talk to mine and see what he suggests, but mine will be a v8 207 with big port heads, reving to atleast 8500. with 92.5mm pistons, 12mm oil pump, and twin scroll 20g
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Old 03-11-2009, 07:42 PM   #22
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I don't see a problem with 2 thou clearance - that is spot on the money imho.

The original rebuild on my EJ207 (done by Subaru) ran just a touch over 1 thou of clearance (using ACL race series bearings) and it spun a bearing within 24 hours of being rebuilt (I actually suggested to them to run looser but they didn't listen). After that failure it was rebuilt with 2 thou clearance and I have not had a problem.

I am a firm believer of that tried and true saying "1 thou clearance for every inch crank diameter".
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Old 03-14-2009, 07:50 PM   #23
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i built a lot of engine for me and friends

i usually manage to get more then 1,5 thou at a minimum, 2 thou at best !

i run mine right a 2 thou, no oil pressure issue, no spun bearing issue neither

i assemble a ej20K at 1,8 thou a month ago, stock everything... MAYBE the oil pressure was a little lower then before, but nothing to worrie about .. i maybe should have shim the oil pump, but it is Ok !


subaru are weird... they should assemble there engine a bit looser on the bearing and on the piston pin.. that would make better engine that dont do piston slap, or spun bearings !!
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Old 03-14-2009, 07:51 PM   #24
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oh i forgot, 2 thou for rod, 1.5 for crank is what i use
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Old 03-14-2009, 08:32 PM   #25
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well i went back today and played around and ended up with them between .0015 and .002 so i guess ill give it a shot. Hopefully i can get my gaskets and finish it up
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