440 rb. Half or fully grooved bearings?

[Rich H.]

I need to order new main bearings for my ‘78 440. It’s a street car/car show car and not a race car. Should I use 1/2 or fully grooved bearings? I’ve seen lots of opinions online for each. Motortrend article recommended 1/2 grooved…?
Thanks
Sonny

Do you want your rod bearings oiled half the time, 3/4 of the time, or all the time?
I defaulted to "all the time" for many years but recently tried "3/4 of the time" on the latest build.

For a street engine the tendency is to default to whatever was stock (half groove), but a person could make a case for full groove bearings in an engine that will be idled around alot at low speeds such as car show events.

there are both long lived street engines and long lived crazy horsepower engines using all three bearing styles, half, full, 3/4. You kind of have to decide what your philosophy is and go for it. the odds are you will probably not have a failure related to the bearing design and will be able to say you were on the right side of it.

 

[Geoff 2]

Millions of car engines ran well for 000s of miles on 1/2 grooved main brgs. Some, like taxi engines, lasted longer than average.....& they spent a lot of the time idling.

 

[66Satellite47]

Do you want your rod bearings oiled half the time, 3/4 of the time, or all the time?
I defaulted to "all the time" for many years but recently tried "3/4 of the time" on the latest build.

For a street engine the tendency is to default to whatever was stock (half groove), but a person could make a case for full groove bearings in an engine that will be idled around alot at low speeds such as car show events.

there are both long lived street engines and long lived crazy horsepower engines using all three bearing styles, half, full, 3/4. You kind of have to decide what your philosophy is and go for it. the odds are you will probably not have a failure related to the bearing design and will be able to say you were on the right side of it.

I think you need to study how a Mopar oil system works. The discussion is not about rod bearings, it's main bearings. Full groove mains were designed to help the high RPM motors.

 

[Rich H.]

I think you need to study how a Mopar oil system works. The discussion is not about rod bearings, it's main bearings. Full groove mains were designed to help the high RPM motors.

I think you need to study how connecting rod bearings are oiled, in particular the source of the oil for the connecting rods, before going any further with this line of thought.

In the context of Mopar V8 usage, Original application for full groove was circle track Hemis at the Daytona 500. Time and experience have shown this design feature may have both additional benefits and downsides beyond design intent, not fully realized 50+ years ago.

Modern school of thought is along the lines of King bearings, they have many satisfied customers with high horsepower applications running 1/2 groove. King bearings have a great reputation.

I'll save you the trouble: The source of the connecting rod bearing oil is the groove in the main bearing, delivered through a hole in the crankshaft between the rod and main journal. Whether you can handle the discussion or not, rod bearing lubrication is directly affected by the style and size of main bearing groove chosen. To make the comical inference one does not affect the other tells me everything I need to know. Have a wonderful day.

 

[Mebsuta]

My dum 383 has fully grooved mains. That's what the machine shop guys told me to do last century. These days I just rumble around the neighborhood and go to 7-11 and stuff. It does just fine. I think I would have been okay with either full or half.