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Rod Bearing question

  
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Rod Bearing question

 
thinman56 thinman56
User | Posts: 110 | Joined: 04/13
Posted: 08/05/13
03:45 PM

So, yesterday I prepped my rods for installation, and I have one glitch.  There'll be questions so here's what I did up front:

1. Cleaned and de-burred, which didn't take much, they were pretty clean;
2. Clamped the rods in a vise with clean aluminum plates to line up the cap and torqued the old rod bolts to 45 ft-lbs;
3. Removed one bolt at a time and replaced with ARP, torqued to 45 lbs to set them;
4. Measured the rod ID, they all were between 2.3742" to 2.3747", as best as I can make a dial bore gage work;
5. Loosened them up and installed the bearings;
6. Re-torqued in increments to 50 ft-lbs and measured the bearing IDs.  Compared to the crank journals the clearances were all 0.0012" to 0.0020", a little tighter than pontiacman8's recommendation, but within Pontiac factory specs.

So, here's the glitch - one of the rod bearings sticks out beyond the side of the rod by a good 0.010".  I tried swapping some bearings around, no change.  It appears than the notches in the rod that secure the bearings are offset on just this one rod.

Anyone got any clues?  Can I trim the edge of the bearing down without ruining it?

Thanks for any feedback.  

70bird 70bird
Guru | Posts: 1064 | Joined: 02/13
Posted: 08/05/13
05:27 PM

the bore of the rod has a radius around .015" wide so are you saying it is actually a total of .025" off center?

This means that there is around .025" of exposed id on the other side.

This also means making it the proper size you have reduced its contact width on the crank by .025" also. This is no bueno.

Can you post a photo or link of one to flickr or similar etc?  

thinman56 thinman56
User | Posts: 110 | Joined: 04/13
Posted: 08/05/13
06:36 PM

Here's a pic:

Rodbearing  

thinman56 thinman56
User | Posts: 110 | Joined: 04/13
Posted: 08/05/13
06:37 PM

Here's a pic:

Rodbearing  

70bird 70bird
Guru | Posts: 1064 | Joined: 02/13
Posted: 08/05/13
07:29 PM

what does the other side look like?

i can see inner rod surface just like i thought.

that rod and/or bearing are not happy.

that bearing is not square in the rod, look at it.  

chevelle83 chevelle83
User | Posts: 235 | Joined: 10/11
Posted: 08/05/13
08:48 PM

how does the thickness of this rod compare to the others?  Looks to me like this rods been worn down a little by either another rod or the crank journal.  

waynep712222 waynep712222
Enthusiast | Posts: 310 | Joined: 03/13
Posted: 08/06/13
01:43 AM

?  

thinman56 thinman56
User | Posts: 110 | Joined: 04/13
Posted: 08/08/13
04:34 AM

Yea, something wrong alright.  First, that is the matched set of rods, I assume from the original engine, the casting numbers are all close.  Four of the rods measured 0.996" at the big end for rod width, but the one in the picture measured 0.937"!  Three others measured between 0.947" and 0.960".  Weird, they don't look machined or worn in a bad way.  

So, I have a spare engine and I took four rods/pistons out of it that all measure 0.996" or 0.997".  Journal width on the crank is 2.003" +/- a thou.  I'll have the pistons popped off those four rods today, and I guess I better weigh them all to make sure the '64's are not different from the 67's.  Any other rod design changes between those two years?  I know a few things changed from '64 to '65.  I'll also check other dimensions, the length from big end to small end, piston pin hole, etc. and make sure nothing else is fishy.

Thanks for feedback.  

70bird 70bird
Guru | Posts: 1064 | Joined: 02/13
Posted: 08/08/13
03:45 PM

So, I have a spare engine and I took four rods/pistons out of it that all measure 0.996" or 0.997".


Lol, it's a GM.


XXXXX


I guess I better weigh them all to make sure the '64's are not different from the 67's.


I would have all 8 rods weight balanced while I was at it.


xxxxx


Any other rod design changes between those two years?


I don't think that is a design change, lol.