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Need your opinion on crank and bearing (PICS)

Specter

Well-known member
Joined
Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
Hi All

Just to give you the background, the existing block I am running is weak. Therefore, I got a seperate engine as backup since I anticipate that existing crank would be spinning bearing soon.

Following are the crank pics (Rod only)










Following are the rod bearing pics




Judging from the pictures, I think the crank is faily in good conidtion, perhaps needs polish. I cannot feel any scratch on the crank with my finger nail.

However, I am a bit doubtful with the bearings. I think I have the following options -

a) Torque everything back to specifications and run this block as it is
b) Get new OEM bearings, polish the crank and run the block
c) Get after market bearings, polish the crank and run the block

I need advice on how to proceed and what would give me peace of mind as far as bearing reliability goes.

Thanks!
 

prove_it

Well-known member
Joined
Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
If you want it to run a long time, then

polish the crank, make sure the machine shop drills out the balls to allow better cleaning.

You NEED bearings. Those are done. I personally really like the ACL race bearings with the .001 extra oil clearance. Main and Rod bearings.

Properly assemble engine.
 

r4pt0x

Well-known member
Joined
Nov 20, 2013
Messages
123
Location
Bavaria / Germany
Easy rule of thumb:
If you can FEEL grooves on the crank (by scratching over it with a finger nail): its bad. If you can SEE grooves in the bearings: its bad.

Ideally you want to get a good crankshaft, otherwise get it polished (regrinding won't last long - the surface is hardened and regrinding will destroy/remove this layer)
The bearings should be measured in at the upper end of the OEM specs for engines which often see high rpms and boost. OEM are good, ACL race are also fine, I also used them in my engine and in lots of other engines - never had them fail (at least if they got enough and clean oil...).
The clearance has to be checked with *any* brand as you absolutely have to avoid even minimally too tight clearances (or much too wide...). Especially the center main bearing is critical and the first to fail.
 

Specter

Well-known member
Joined
Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
Thanks for the response.

I have read the post on our forum regarding drilling out the balls to clean out the crud behind them and allow better cleaning. Sadly, the machine shops are not very good around here. So lets see how that goes.

I was also of the opinion that i need bearings. Although i do not feel any groves on the bearings either, but the way they look, seems that they wont last long. I would also mention that around here, there is very fine dust in the atmosphere. Its like sand. So its my top priority to get the block up to the mark as far as bearings go so i can have peace of mind and run high boost knowing that I tried stregthen it.

The issue with failing bearings in my 4g63t experience has been so severe that I even got another spare crank sitting around. I also got this spare one with this engine. So I really want to resolve it. Having a 4g63t not running high boost due to weak bearings is very sad.

Now that we have established how to go further. I need to order bearings. My choice is also ACL, however i am unsure on the type of ACL bearings to use. I understand the clearance issues.

The way assembly shops work around here, I would like to keep the shop work to bare minimum and least techinical.

I will search around the ACL website specially keeping the ACL race bearings in mind.
 

AllanL

Well-known member
Joined
Aug 4, 2008
Messages
294
Location
NV
where's a good place to get those acl bearings?

thanks!
 

prove_it

Well-known member
Joined
Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
My acl bearings with the extra .001 oil clearance spec'd out at a perfect .002" across every journal on both crank and rods.

Not sure what your power levels are. That makes a difference.
 

biglady112

Well-known member
Joined
Sep 30, 2005
Messages
1,255
Location
Commerce City, Co
We have been running machined crankshafts for years. ZERO issues. We also run any cheap bearing we can get. I would never pay extra for some bearing that is advertised as being looser. I trust mine and my machinists measuring tools. I also cut the crankshaft to each bearing on a new build
 

Specter

Well-known member
Joined
Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
I guess you need a very good machinist to run machined cranks. I am running a machined crankshaft right now, the bearings are weak and crank has marks you can feel. It might be a bad machinist, or contamination during assembly, or could be oiling issues.

But I cannot trust the machinist around here. Therefore, I prefer to stay with the original cranks.

I wonder how many people are running machined cranks with no issues at all.
 
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