340 main bearings

[EMPennell]

Hello everyone, my name is Eryn Pennell and I was hoping I could get some clarification on my 340. This is my first post so go easy on me.

I inherited my dad’s 66 valiant 340 and am in the process or rebuilding a new 340. Ive never built a 340, but have built a few engines before.

While taking the engine in the car apart I noticed there are upper main bearings on both sides of the crank in #1, 2, 4, 5. The only lower bearing was #3 thrust. Is that normal for these motors?

Thanks!
EP

 

[NC Engine Builder]

Those are just "full groove" bearings. Completely normal

 

[EMPennell]

Those are just "full groove" bearings. Completely normal

Thank you!

 

[teringer]

Why is the thrust bearing not fully grooved in the center or have I forgot

 

[Newbomb Turk]

Why is the thrust bearing not fully grooved in the center or have I forgot

I never nailed down an answer for that. The closet I ever heard was Chrysler called out the thrust main on the 340 bearings only have a half groove for some reason I have long forgotten.

If you get the bearings called out for a 318 all the mains will be grooved. Why that is I haven’t the foggiest notion.

Now that I type that out I may have that backwards. It might be the 340 bearings with a full groove thrust. Either way that’s how I remember it.

Even thought the dimensions are the same they call out different part numbers for 318 and 340 bearings.

 

[perfacar]

the clevite 318 mains fit, number is ms 1344P, all bearings are full grooved