Topic: Full circle groove main bearings

[sirdeuce]

Anybody have thoughts on going full circle on the main bearings? This is where two sets of main bearings are purchased and the oil grooved set from both sets are used so the rods have an uninterrupted supply of oil. It does reduce the surface area on the load bearing shell (bottom) I know, but the rods are well oiled. I did this 'mod' on some of my higher revving engines and it did reduce the rod bearing issues. The I found a bearing company that did a 3/4 groove for those engines. First time I've considered doing this on an R series engine. Never had a problem with the mains on a 22R but the rods go out often enough.

[Gnarly4X]

Anybody have thoughts on going full circle on the main bearings? .

Hey sirdeuce,

In my experience, which is limited, I don’t recall an unusual rod or rod bearing problem in the early 22s.  In other words, I have not read about or heard from any of my fellow Toyota truck wheelers that the rods or rod bearings came up in discussion as a failure.  In fact, it’s always been my belief that the bottom end of these engines is incredibly strong.  The posts that I have read on some forums where a rod bearing was the topic, that to me was almost always neglect, poor maintenance, low quality part, poor workmanship, or just abuse.

With that said, I don’t think there is anything misguided about prepping an engine with better parts and blueprinting.

Gnarls. 

[CB.TypeG]

I had a rob bearing failure in my early 22r but who knows how many miles of neglect that motor experienced

[sirdeuce [OP]]

I tend to abuse my engines. Being hard on any machine tends to get one looking for a way to reduce frequency of failure. Many of the 22R engines I've torn down had perfect main bearings with rod bearings showing much more wear, or even failure.
Most suggest chamferring the oil hole in the crank journal. That chamfer does well enough in guaranteeing oil supply to the rod bearing, but I still want a bit more. In 4AGEs this mod reduced the frequency of the rod failures I've experienced. Most of those failures were in engines that regulrly saw RPM in excess of 9000rpm. Then I found ACL race bearings have a 3/4 diameter groove that covers the issue very well. Might just end up having the lower bearing shells machined to make a 3/4 groove.

Bearing failure frquency I've seen is, greatest to least, rod bearing, thrust bearing and then main bearings. Thrust bearing failures have been primarily in manual tranny set-ups.

[Gnarly4X]

I tend to abuse my engines. Being hard on any machine tends to get one looking for a way to reduce frequency of failure. Many of the 22R engines I've torn down had perfect main bearings with rod bearings showing much more wear, or even failure.
Most suggest chamferring the oil hole in the crank journal. That chamfer does well enough in guaranteeing oil supply to the rod bearing, but I still want a bit more. In 4AGEs this mod reduced the frequency of the rod failures I've experienced. Most of those failures were in engines that regulrly saw RPM in excess of 9000rpm. Then I found ACL race bearings have a 3/4 diameter groove that covers the issue very well. Might just end up having the lower bearing shells machined to make a 3/4 groove.

Bearing failure frquency I've seen is, greatest to least, rod bearing, thrust bearing and then main bearings. Thrust bearing failures have been primarily in manual tranny set-ups.

If you are pushing even a Gen 5 4A-GE to 9,000 RPMS   , then yes, you'd better be installing best parts you can find! 

Gnarls.

[sirdeuce [OP]]

5th gen 4AGE=5 valve per cylinder, ITB, 160hp @ 7800rpm, 8100rpm fuel cut. STOCK. With my 16v 4AGEs I run an 8800rpm rev limit on stock internals. Oil pump being the weak link in that chain. A set of upgraded pump gears gets to 9500rpm well enough. Generally speaking, a 9000rpm 4AGE in any geration, is no big deal. A 9000rpm 22R? Now that is something else.