Moparchat - Home of MOPAR enthusiasts worldwide!



Go Back   Moparchat - Home of MOPAR enthusiasts worldwide! > Technical Forums > Performance Talk

Click here to search for Mopar cars and parts for sale.


Reply
 
Thread Tools Display Modes
  #1  
Old 01-10-2000, 06:03 PM
Molloy Molloy is offline
Inactive User
 
Join Date: Jan 2000
Location: Austin, TX, USA
Posts: 71
Angry

After finding flakes of tin in my oil filter, I checked my rod bearings and they're all starting to delaminate. The motor is a striked 440 with a 4.15 mopar crank (from McCandless). Its a kind of a heavy rodded motor, with C&A speedway rods, but was balanced with heavy metal.

The rod bearings (Callies) look hammered, have cracks, and chunks missing like it was delaminating. The bad smell comes from measuring the crank's rod journals, which turned out to be: 2.371, 2.370, 2.370, 2,370. So it looks to be 5 thou under the nominal 2.375. The trouble is that the engine builder used STANDARD SIZE BEARINGS. This guy claims he measured the clearance and it was ~3 thou, but I'm not sure that's possible with 5 thou undersized journals. I would have expected the clearance to be over 5 thou? Here's the weird part. My oil pressure was great (Milodon hi vol pump). Maybe the tight side/side clearance of the C&A rods kept the pressure up?

The crank looks to be in good condition in spite of the bearings, but I'd like to ensure this doesn't happen again.

My questions are:
Did this happen because of the clearance, or because of the heavy reciprocating assembly, a combination of both, or possibly something else?

What is the best bearing to use with a heavy rodded stroker that will see a lot of street action?

Whats the deal with 80+ psi oil pressure if my clearance is so bad?

Anyone know a really good machine shop in Central Texas? Anyone know a really good psychotherapist so I don't KILL my engine builder (who is trying to blame me for the failure)?


------------------
Molloy
Reply With Quote
  #2  
Old 01-11-2000, 12:03 AM
MopART MopART is offline
Inactive User
 
Join Date: Jan 2000
Location: Greenville MS USA
Posts: 287
Post

I say ask your engine builder if he's seen Texas Chainsaw Massacre and ask him if he wants to audition for the lead victim in the next episode.
I wish I had some good tech. info for you, but in these cases where their shouldn't have been a problem and there was - well, go figure.
How long did the motor run before you realized you had a problem and what was the symptom that showed a failure ?
Stupid question: The valves weren't slightly tapping the pistons, were they ?
Reply With Quote
  #3  
Old 01-11-2000, 01:38 AM
Christopher's Avatar
Christopher Christopher is offline
Inactive User
 
Join Date: Mar 1999
Location: fl
Posts: 2,018
Post

Severe detonation will beat the snot out of rod bearings also.
Reply With Quote
  #4  
Old 01-11-2000, 01:45 AM
Thunderstruck Thunderstruck is offline
Moderate anarchist
 
Join Date: Jan 1999
Location: San Angelo, TX, USA
Posts: 336
Post

Hey,

I can't remember the name of the shop we used but I remember where it is. It's back behind the Weiners just north of Robert Mueller (ex airport). Of course it wasn't a stroker just a 360 built for abuse. What was the name of the shop you used? You a member of the local Mopar club? we meet first Tuesday of each month at H.O.T Dodge, 6:30 pm.

Steve
Reply With Quote
  #5  
Old 01-11-2000, 01:52 AM
451boy 451boy is offline
Inactive User
 
Join Date: Dec 1999
Posts: 286
Post

I'd think you would want to use a fairly hard bearing like a TriMetal for that application. You should hook up with some bearing manufacturers catalogs and take a look at what they offer. What does C&A say? They sell a lot of bearings.

I think your engine builder put it together wrong. Even 0.003 is way too much clearance for a street motor. I'd think you would want something more like 0.002, or 0.0015.

As for the oil pressure at 80 psi with big clearances, what kind of pump do you have? A big pump can ram plenty of oil in there. What weight of oil were you running? Where are you measuring the oil pressure? Remember, the back of the block measures the pressure in the oil gallery, not at the crank. There could be a major drop in pressure from the gallery down to the rods since the oil has to fight it way down those passages to the main bearings, then squirt into the crank and up the feed passages to the rods. Who knows what oil pressure the rods were actually seeing?
Reply With Quote
  #6  
Old 01-11-2000, 10:00 AM
DartGT66 DartGT66 is offline
Inactive User
 
Join Date: Sep 1999
Location: vantaa,finland
Posts: 4,622
Post

I think it can't be a oil pressure problem. If there is too little pressure the film will collapse and the pearing will spun, not flake like in this case. I use the regular CB527P clevite bearings in my engine. When I bought the engine, the bearings were just like Molloy described. The crank was measured and it was OK. I have never measured the clearances, but the previous owner said they were .003", on the big side. I also had main cap movement, and after one year of driving I pulled the pan and checked the bearings, the main caps had walked again, but the bearings seemed okay. I will check them again this spring just to be sure. Anyway, the previous owner did all kind of 'tuning', and I think the bearing problem was caused by detonation.
Reply With Quote
  #7  
Old 01-11-2000, 07:24 PM
Molloy Molloy is offline
Inactive User
 
Join Date: Jan 2000
Location: Austin, TX, USA
Posts: 71
Post

The motor had 3100 miles when I finally pulled the caps.

The oil is Kendall GT-1 20-50

The block is a Megablock with x-bolted mains, so I did not expect cap walk.

No valve tap, plenty of clearance.

Oil pressure was measured at the back of the block.

The milodon hi vol external pump should be able to provide plenty of volume, but I guess you never know.

What do you think of bushing the lifter bores. I'm using a Crower solid roller (smallish), and many have suggested that the roller lifters bleed-off a lot of oil. Maybe that would contribute to an oil problem in the rod journals?

Hey Steve, I'm the guy with the Orange 69 Charger. I've been to some of the meetings. BTW I'm going to have it painted now that the motor is out. Thinking about dark forest green, gunmetal grey, or silver. What do you think a good color would be(no AC-->no black)
?
Reply With Quote
  #8  
Old 01-11-2000, 08:50 PM
sanborn sanborn is offline
Inactive User
 
Join Date: May 1999
Location: shelbyville,tn,USA
Posts: 2,880
Post

I have a few suggestions based on our experiences. At high RPM ( above 7000 ) I don't think the standard oil hole in the main bearing is large enough. We machined a slot 1/4" X 1/2" to allow more window to oil the crank ( see if you can find a photo of the old Nascar main bearings they used in big blocks ). Also, we found that some cams had the rocker oiling holes opening at the same time as the crank hole creating a volume drop. Therefore, we oiled the rockers externally and plugged the block passage. You do loose some pressure around the lifters but not much if the lifters are in good shape. As someone mentioned, there is a big pressure drop between pressure at the back versus the main bearing, we used two gauges and found 15 lbs. difference. I have wondered if the action of the lifters in the oil passage creates turbulence at high RPM. Try to keep rod side clearance low, around .008". Too much clearance allows too much oil to escape. That can cause flaking. Hope this helps.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Thrust bearing failure 440 Bcuda59 Drag Racing Forum 14 01-21-2009 02:54 AM
2000 ram 2500 van front bearing failure MitchP1 Ram Truck Chat 10 04-20-2005 08:58 PM
440 rod bearing failure by transmission sbon Performance Talk 2 11-01-2003 03:03 PM
What causes Trust bearing failure? Ted Bromback Vintage MOPAR chat 2 12-08-2002 03:24 PM
440 and no.6 rod bearing failure MOPARCHAS Drag Racing Forum 0 05-30-2002 10:01 AM




All times are GMT -4. The time now is 09:49 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
. . . . .