Main bearing clearance question - 460 Ford Forum
Engine Tech A place to discuss all 385-series engine tech and theory.

User Tag List

 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 7 (permalink) Old 07-06-2008, 01:01 PM Thread Starter
Senior Member
 
mico's Avatar
 
Join Date: Nov 2006
Location: Lakewood, Colorado
Posts: 326
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Main bearing clearance question

Guys, I have a D1 block that has been line bored, Im using a Clevite standard size bearing. Is there a standard diameter that I should be getting when measured? I get a main of 3.001, crank reads 2.989 which is .012 clearance. When I use green Plasiguage it shows .001 :?
Whats the best way to measure this?

Mike G
64 fairlane
572 C head twin turbo coming soon
mico is offline  
Sponsored Links
Advertisement
 
post #2 of 7 (permalink) Old 07-06-2008, 01:23 PM
Senior Member
 
Join Date: Jan 2006
Location: Michigan
Posts: 593
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Even experts make a mistake once in a while, I suspect your measurements or math are off. Plasti-gauge is not as good as accurate measurements. Measure the main housing bores. If those are within spec, install the bearings, torque the caps, and measure the bearing IDs. Then, measure the crank journals. All these measurements should be made at multiple points, and obviously must be accurate. If the clearances determined by measuring vary much from a properly done plasti-gage reading, the block and/or crank are not straight. Also, assuming the crank endfloat is ok, and the main journal fillets clear the bearings, the crank should spin easily. If it doesn't, that also could be an indication of a crank/block problem.
CutawayAl is offline  
post #3 of 7 (permalink) Old 07-06-2008, 01:42 PM Thread Starter
Senior Member
 
mico's Avatar
 
Join Date: Nov 2006
Location: Lakewood, Colorado
Posts: 326
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
The block just came from the machine shop. Bored, decked, linebored it was 1/2 filled prior to machining. The crank is a new Scat forged 4.5. I installed the crank with permetex assy lube and torqued to 100lbs crank spins with very little effort (easy). I dont belive that there is a problem with the block or crank. I just need to get the clearances figure out. My mics measure the same as the machine shop on the crank so I assume that its calibrated.
What measurement should I get with the bearing installed and cap torqued?

Mike G
64 fairlane
572 C head twin turbo coming soon
mico is offline  
post #4 of 7 (permalink) Old 07-06-2008, 03:47 PM
Senior Member
 
TopSportsman916's Avatar
 
Join Date: Sep 2007
Location: NC
Posts: 1,778
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Mike, get you a good dial bore gauge that reads to .0001. Then you can install the bearings & caps & get an accurate reading to compare to your crank journel sizes.

Chris

VPRC 1998 Mustang
557 CJ :1.15 60', 5.32@129.58 mph @ 2600lbs
665 C&C Hemi : To Be Determined
http://img146.imageshack.us/img146/2158/ricksadql2.jpg
TopSportsman916 is offline  
post #5 of 7 (permalink) Old 07-08-2008, 02:23 AM
Junior Member
 
Join Date: Jan 2006
Location: Englewood, CO
Posts: 38
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Hey Mike,
Isn't engine building fun?
Main and rod bearings have been one of our biggest sources of frustration over the last decade. Trying to hit target clearances is just a royal pain in the butt! The bearings just aren't very predictable anymore. I used to be an avid supporter of the Federal Mogul performance bearings, and hated the Clevites. However, after F/M switched bearing production to Mexico, they have become absolute pain in the arse, never a consistant size. So, we've been switching back to the Clevite's, and they have actually gotten better than they were in the late 90's.

But, we still end up having to try numerous sets, mix and match .001's and X's, etc to try and get to target clearances. And just because a set is sized at .001, doesn't mean it will be a thou tighter than the STD's. That's only a theory. You just have to install and measure........install & measure...........install & measure..........

We have tried some of the Kings and the ACL's with good results. Some have come back in race engines and seem to be holding up just fine. The thing about 'em is if you hone the housing bores on the split, have the crank on the low, and install the bearings, you almost always end up with a workable clearance the FIRST time. What a f#@king concept! F/M & Clevite have forgotten how to make a damn bearing. So we waste hours upon hours with their crap trying to get clearances. I know Barry has nothing nice to say about the Kings and ACL's, but after all of the problems we consistently have with the F/M & CL's, I don't know why..............

Sorry, the bearing topic will start me on a real rant.
RobMcQ is offline  
post #6 of 7 (permalink) Old 07-08-2008, 09:13 AM
Senior Member
 
Join Date: Jan 2006
Location: Roseville MI
Posts: 10,745
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 71 Post(s)
 
That clearance is entirely within the specs of a regular rebuild, grocery getter type engine. They are on the tight side of those acceptable OEM limits.

A high performance or race engine is an entirely different story.
There are some "rules of thumb" however, the biggest parameter on clearance is how will the engine be loaded and the desired clearance depends a lot on the strength of the crankshaft and the type of metal it's made from, whether the block material is on the brittle side or mallable and what weight and type oil is to be used, etc.

www.rmcompetition.com

R.M. Competition - The finest Custom Engine Building for any venue ... !
Selling Parts and Supplies from companies I use ... 1(586)909-1591

CUSTOM ground camshafts
Carburetor modifications for specific applications
CNC porting
rmcomprandy is offline  
post #7 of 7 (permalink) Old 07-08-2008, 12:41 PM
Senior Member
 
Barry_R's Avatar
 
Join Date: Jan 2006
Location: Detroit
Posts: 791
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Actually I don't have a big problem with ACL. They are OK parts. I don't like King though. When we checked them - and I had SERIOUS checking tools back then - the King stuff was all over the map for profile, and the material was nothing like they claimed.

I have a bigger problem with companies that make up stories and lie to customers than with companies that simply don't have the resources to deliver a particular part. King was selling low budget passenger car rebuilder quality parts with marketing claims of them being superior to legitimate race hardware.

Maybe they've learned better....it's been at least 3 years.

Barry R.
#1 Horsepower FE Ford - Engine Masters Challenge - 2005, 2006, 2007, 2008, 2009, 2010
Warehouse Distributor for:
Scat, Probe, Blue Thunder, Diamond,
Clevite, Holley, Federal-Mogul, Comp Cams, more.
www.survivalmotorsports.com
(248) 931-0358 or (248) 366-3309 shop
Barry_R is offline  
Sponsored Links
Advertisement
 
Reply
Gear in this thread - Powered by O'Reilly Auto Parts

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the 460 Ford Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome