My question is if you have a main bearing set can the top bearing [with oil groove] be put in the main cap for full groove? Say in a SBF or SBC.
I don't see why you can't. However, the lower bearing on a crankshaft main has the most load. That's why they make it a full surface bearing.
Usually they're offset so you can't do that. Because it's not a good idea. Journal bearings get their "strength" from the width of the bearing surface. This surface holds the oil film between the bearing and crankshaft journal. If you cut it in half, with a groove, you get a bearing that will support less load.
Yes off set is the problem. The ***eol [Crosley derivative] that I took apart to my surprise had full groove main bearings and for another surprise they cut the tang reliefs in the caps to suit the upper bearing tang location [off set] so the Crosley replacement bearing with no groove sticks out of the bearing bore by .075 and hits the crank so it can't seat.. This is just on bearings #2, 3 ,and 4. #1 and 5 will fit either way, top or bottom. I have a new Crankcase and it is the same. This engine version was used in a nose up or nose down boat application but there was horizontals too and Crosley replacement for the military. Ok, got to have opinion on how to get and keep the full bearing in place in the cap. I can file the cap tang relief or the tang to slide the bearing over [or some on each]. I am thinking a br*** dowel to keep them in place like in alum rods?
Full groove isn't made...for a reason ! The load carrying capability drops significantly with a full groove bearing. We all learned that back in the 1960's early 1970's. NOT...a good idea. Mike
Yes not a good idea. Problem is I have 1/2 groove bearings and they don't locate in the caps, .075 off, bearing has to move.
one of these days, you'll take some pictures so we can see what you're working with, because the descriptions so far have me confused.
Before the internet and internet forums there were these thing called "books". You could get one , open it, and read, and learn. They are amazing, and a wealth of knowledge and information, and still work great today .
I think these show all I been babbling about. Top cap has original full groove bearing and lower cap in each pic shows new solid bearing, about .075 out of location.
Thanks that was real helpful. If I had a book I wouldn't be here, I would know why they used full groove bearings [maybe] and in the last years at twice the HP they still used full groove and the overall bearing width was reduced.
looks like the new bearings might just be made wrong? One thing about this engine, the bearings are really wide, so it's likely that it will work fine with a groove in the lower half. That's something that was not obvious, before seeing the pictures.
The relief in the cap was made to accommodate the upper grooved half. In a Crosley crankcase the tang reliefs are so you can't swap top and bottom halves.
Get another set of bearings or widen the groove in the cap. Those tangs are for location during installation they don’t hold the bearing in place in use, it’s the clamping force of the cap that fixes the bearing in place.
The Jalopy Journal
