392 Cam Bearings - To Change or Not To Change

Scouty

Scouty

Member
I just picked up a 392 with 73,000 original miles. After tearing it down, it really does look like the miles are correct. Everything looks goods. Because everything looks so good, the plan is to flush the water jackets, replace the freeze plugs, replace all gaskets and seals, and give it a fresh coat of paint. However since it is apart was wondering if replacing the cam bearings is a good idea? Here are some pics of 2 of the bearings.

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Matt,
I recently broke down that 196 and get it all back from the shop tomorrow. My mains and rods looked a little worse than those, but the crank polished out and I'm just going to put in new bearings. If you have it that far apart, you May wish to have the crank miked and polished, and install new bearings. What do the cam bearings actually look like?

Give me a call on the cell.
 
Is this a test?

Rod vs cam?

Pic vs words?

I have a set of cam bearings. I don't have the install tool anymore, sold it last year. But fwiw, you can buy one on e-bay and then sell it when you done :idea: I've set a few and it is a lot easier if you pull the crank that's for sure. Otherwise you have to go slow and steady with 20lbs in you hand.
Crank bearing replacement is a ton easier.:icon_up:
 
I sure don't like the looks of that top bearing. From the pics it appears to me a case of fatigue, and the left side of the journal in the crank pic doesn't look so good either. The pits and adjacent smearing looks like fatigue signs. I originally thought of corrosion, but I don't see any sign of etching to go with the pits.

If was my engine for the long haul, it's overhaul time and the cam bearing question would be moot. I can live with a slapping piston, but a bearing like that would be a crap shoot.
 
I'll 2nd to that.do it right the 1st time.tear it down an do the cam brgs., why take a chance?they are the life of the motor.oil pressure..stems from them.if you can't do it your self,any machine shop won"t do them for you unless the block is stripped.Jeff
 
All the bearings I see in that set of pics tell me...they are shot! I see much embedded particulate (that is something they are supposed to do!), along with all kinds of other anomalies.

I'd never consider using those for anything other than additions to the recycle pile.

The crank journals must all be measured for their basic dimensions and any imperfection is going to have to be handled by having the crankshaft ground. I can actually see the rod journal surface imperfections in the picture.

Don't ever service one of these blocks without replacing the cam bearings correctly. We have tons of information right here regarding this issue and you can see that many machine shops do not do the cam bearing replacement as it should be done.
 
Michael and Robert,
glad I read your stuff on cam bearings before taking my engine apart. Knowing that getting cam bearings properly set can be an "iffy" proposition, I was relieved to do a quick evaluation of the block I just got back and confirm that the cam bearing holes are indeed lined up. Even that little spit hole that sprays onto the cam gear. When I install the cam I'll be able to confirm if the rearmost cam journal groove lines up with that oil feed hole.

A little off topic, but right now I'm having difficulty in lining up moly rings in 0.020" over for a 196. They are available in standard and 0.030", but not 0.020". Chrome are readily available, but aren't those too hard on the bores?
 
Chrome ring's? Not really,if you can get them,then put em in.I never had any probs w/them.the blocks are hard,w/nickle in them.Jeff
 
Mark pietz said:
a little off topic, but right now I'm having difficulty in lining up moly rings in 0.020" over for a 196. They are available in standard and 0.030", but not 0.020". Chrome are readily available, but aren't those too hard on the bores?
Click to expand...
Moly 3/32+3/16 4.145 sets seem to be readily availible. Call Jeff.
 
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