Are you running an aluminum block hemi? if not a waste of time..Hello.
Want to replace main bearings in 4.0 engine.
The aluminum ones are cheaper and the write-up
describing them sounds okay.
Does anyone have any first hand experience with these
aluminum engine bearings?
Thanks for your time
I don't understand why aluminum bearings would be used even with an aluminum block since the crank and thus the crank's bearing surface is steel. But then what I know about rod bearings is less than what I know about brain surgery lol.Similar flex and expansion. Aluminum bearings in an iron block, the aluminum expands and tightens up the clearances up to the point of possibly seizing the engine.
Thanks much.There is some misconceptions in this thread.
Bearings are typically either tri-metal using traditional copper lead and babbit construction, or bi-metal using aluminum alloy with tin and silicon.
For my stroker build I installed King aluminum alloy bearings. They have a more consistent surface thickness, resist seizure during brief oil film collapse, good particulate imbedibility, and longer service life. For the cam bearings I used DuraBond.
If you are not rebuilding the engine, or at least resizing/resurfacing the journals, you can't just slap in some new bearings and expect it to work. The factory mixes and matches slight undersized/oversized bearings to account for machining tolerances at the plant. You will do more harm than good if you just replace the bearings without checking the oil clearances.
So assuming all the clearances are correct, which is better for these 4.0 engines? Bimetal or trimetal? I just purchased a new set of main bearings and they are trimetal. Didn't find out there was a difference until I ordered these ones in.I can't speak to other engines but the 4.0 will have various colored paint marks on the caps to denote what bearings were used. In mine the upper mains were standard but the lowers were .0005 (five ten-thousandths of an inch) undersized to tighten up the oil clearance. If I had simply swapped in standard bearings my oil clearance would have grown a half thousandth. When clearances are only 2-3 thousands that a huge difference. Factory fractional under/over bearings are not available, and aftermarket bearing companies only make then for the most common engines around such as small block chevy's.
In my case the #1 connecting rod was bent (hydrolocked?) and I tried to make an economy fix with a used rod and new piston and rod bearing. Then I discovered the pistons need to be a matched weighted set. That pushed me to just do a total engine rebuild.
Trimetal is pretty standard today. They’re a good choice.So assuming all the clearances are correct, which is better for these 4.0 engines? Bimetal or trimetal? I just purchased a new set of main bearings and they are trimetal. Didn't find out there was a difference until I ordered these ones in.