1973 340 Cam Journal Bearings

[73'cuda]

I have someone rebuilding my 1973 340 motor out of my 'Cuda and they have run into an issue where 1 or 2 of the cam bearing journals are a different size than the other two. They said this was not to unusual and the factory had different size cam bearing they would use on the assembly line to get them all to fit in the cam bearing journal housing. They are talking about shaving the new bearing they have in order to make it fit.
Has anybody heard or actually experience this when working on a 1973 LA 340 engine.
The 1973 was the only externally balanced 340 block, is that true?

 

[TC_Cuda]

I have not heard of this kind of cam bearing issues, but considering the manufacturing tolerances at the time I am not that surprised.
As far as a cast crank goes. The cast crank was first used in a 340 in April 1972

 

[Steve340]

Try ringing Hughes Engines to me it does not sound right. The 340 is a common type of engine there should be no need to shave bearings in fact I would not be doing that.
The cam bearings are different sizes as they must be fitted in a specific order in some motors.
Not sure about the 340 though.
I think I read somewhere the later 340 is externally balanced.

 

[AUSTA]

I have someone rebuilding my 1973 340 motor out of my 'Cuda and they have run into an issue where 1 or 2 of the cam bearing journals are a different size than the other two. They said this was not to unusual and the factory had different size cam bearing they would use on the assembly line to get them all to fit in the cam bearing journal housing. They are talking about shaving the new bearing they have in order to make it fit.
Has anybody heard or actually experience this when working on a 1973 LA 340 engine.
The 1973 was the only externally balanced 340 block, is that true?

Both the 70 la340 blocks i have have staggered cam bearings you can check by sliding onto camshaft to check size & which bearing is for which casing journal
My cam was a bit tight after fitting so i put a dowel in the threaded end & used plenty of good oil then spun with a drill working the cam back & forth until it freed up.

 

[mickeyvb]

Are you talking about the block's cam journal inside diameters, or the cam journal's outside diameters? If it is the cam's, I'd think about replacing it, so you don't have to worry about it down the road. As a plus, you can improve perf with mild cam (Lunati Voodoo is good!) at reasonable cost vs gain...

 

[moparleo]

Never mickey mouse your engine parts or proper machine work. It sounds like you need to go to another machine shop. Have the cam journal holes checked for straightness and diameter. If it is out of specs it is a simple matter of align honing the block. The same as is the main beaing caps were not within specs. You would not sand the bearings down if they were tight, you would have the main caps/block remachined to the proper specs. Other wise you risk spinning a bearing, causing major damage to the block and camshaft.

 

[TC_Cuda]

I have to go with moparleo ... Get good machine work from a reputable shop.

 

[moper]

The rear-most is the smallest OD - so they can be installed from the front. None should have the same OD. I am less sure of the ID but I believe the first 4 are the same and the rearmost 5th is smaller.
So to your question... What's the wrong size? ID or OD, and which positions?