SBC Mahle Narrow Rod Bearing Issue

[fabr]

Are You installing the bearings correctly ? They are marked lower and upper. If installed wrong the bearing is offset wrong. You remarked that some have enough clearance and some don’t. Maybe some are in wrong.

Thank you very much. I have never used the Mahle narrowed bearing since I had a LOT of Clevite chamferred bearings I had been using for years and had run out. It didn't even cross my mind until I got the height mike out and was checking dimensions. My old eyes finally focused in on the upper and lower markings when I saw some with one tang location and others different. I knew then it had to be something I was doing wrong.Problem solved with learning something new to me. I do appreciate your very helpful reply even though I had figured it out. I might not have though and your answer was spot on.

[fabr]

SFAIK there are none.

Then you haven't really looked ...
Off the top of my head I can tell you that a CB-1227 is for the same journal size but, even narrower.

For what it is worth to you ... you can file the tang right off; an engine builder wouldn't need it.

Yes there are narrower but I wasn't interested in a bearing a lot narrower is what I should have written. From what I was seeing (incorrectly)it was about .020.. ANyway,there is a reason I was asking as this place usually has someone with the correct answer. You did not offer the correct answer until another brought it out. In all honesty though I think your answer about filing the locating tang off and "an engine builder wouldn't need it "was just a bit sarcastic and not good info for an engine that will need bearings again and the PITA it would add to that making sure there was enough radius clearance each time. You are,of course,correct that the tang serves no purpose retaining the bearing ,it is only for,wait for it........locating the shell. Many newer engines don't use a tang but rather a fixture/jig to properly locate the shells in the rod/cap.Thanks for the replies .

[BillK]

What kind of rods are they ? I have never had this problem and also have to wonder if you are installing them correctly ?

[fabr]

Just 2 posts previous this was acknowledged.

[Walter R. Malik]

SFAIK there are none.

Then you haven't really looked ...
Off the top of my head I can tell you that a CB-1227 is for the same journal size but, even narrower.

For what it is worth to you ... you can file the tang right off; an engine builder wouldn't need it.

Yes there are narrower but I wasn't interested in a bearing a lot narrower is what I should have written. From what I was seeing (incorrectly)it was about .020.. ANyway,there is a reason I was asking as this place usually has someone with the correct answer. You did not offer the correct answer until another brought it out. In all honesty though I think your answer about filing the locating tang off and "an engine builder wouldn't need it "was just a bit sarcastic and not good info for an engine that will need bearings again and the PITA it would add to that making sure there was enough radius clearance each time. You are,of course,correct that the tang serves no purpose retaining the bearing ,it is only for,wait for it........locating the shell. Many newer engines don't use a tang but rather a fixture/jig to properly locate the shells in the rod/cap.Thanks for the replies .

You claimed that there was not a narrower bearing available ... there IS, although maybe narrower for what you wanted.
Even the chamfered Clevites of the past had an upper and lower but, they were obvious where the Mahle bearings are not.
I gave you credit, at first, for knowing this and I should have realized differently.
Sorry, I ruffled your feathers.

EDIT: by Engine Builder ... I meant "who does this for a living"; there was no sarcasm intended.

[fabr]

I accept you apology and explanation. Please accept mine in return. FWIW I have not done engine building for about 25 years now for a living. I owned/operated my performance oriented machine shop for about 20 years ('78-98) with a reputation for being up to date with procedures before I decided I liked money more than doing what I actually loved doing. I readily admit there have been a lot of changes the last 25 years and I have lost out on a lot of what is glaringly obvious,such as this topic, to those that have continued to learn and practice the craft daily . Thank you for the replies.

[BillK]

I still don't see what brand rods they are ??? Is there any possibility that the rod is the problem ?? Or you are putting the rods on the journal wrong ? Do you have a set of stock rods ? If so take two caps and put two lower bearings in them and sit them on a rod journal and see if they clear. I just tried one in a stock late model 350 rod and there is enough clearance to clear at least a .125 radius.

[fabr]

I still don't see what brand rods they are ??? Is there any possibility that the rod is the problem ?? Or you are putting the rods on the journal wrong ? Do you have a set of stock rods ? If so take two caps and put two lower bearings in them and sit them on a rod journal and see if they clear. I just tried one in a stock late model 350 rod and there is enough clearance to clear at least a .125 radius.

Are You installing the bearings correctly ? They are marked lower and upper. If installed wrong the bearing is offset wrong. You remarked that some have enough clearance and some don’t. Maybe some are in wrong.

Thank you very much. I have never used the Mahle narrowed bearing since I had a LOT of Clevite chamferred bearings I had been using for years and had run out. It didn't even cross my mind until I got the height mike out and was checking dimensions. My old eyes finally focused in on the upper and lower markings when I saw some with one tang location and others different. I knew then it had to be something I was doing wrong.Problem solved with learning something new to me. I do appreciate your very helpful reply even though I had figured it out. I might not have though and your answer was spot on.

BillK please read the above. I do appreciate your willingness to help. The issue was my ignorance. Problem solved.

[fabr]

I still don't see what brand rods they are ??? Is there any possibility that the rod is the problem ?? Or you are putting the rods on the journal wrong ? Do you have a set of stock rods ? If so take two caps and put two lower bearings in them and sit them on a rod journal and see if they clear. I just tried one in a stock late model 350 rod and there is enough clearance to clear at least a .125 radius.

The new rods are Callies. I had been using Olivers and I knew they cleared the fillet with the older Clevites chamfered bearings. I used the height mike to compare tang locations in each. There was a .020 difference in tang location with the Callies being offset towards the fillet. The Oliver rods would clear the fillet even though I had the shells in wrong positions.Approx .020 is what I was seeing as the needed bearing movement away from the fillet and that was coincidentally the difference in tang location between the 2 brands of rods. This is what was fooling me even though the actual issue should have been clear as day. At first I thought Callies was at fault even though it was unlikely since I failed to see the very tiny upper and lower designation on the back of the shells and had one set correctly installed and the other was upper/lower in wrong positions. As I stated previously,I had a lot of the old Clevite chamferred bearings left still in stock from when I ran a machine shop that I had been using the last several years and since it was damn hard to get them wrong I made a dumb mistake with the Mahle narrowed / not chamferred, as I assumed the narrowed bearings were narrowed on both sides and not just the side facing fillet. Just for info the Callies crank fillet radius is 9/64,slightly bigger than the .125 we normally see . That and the fact the tang location was/is offset.020 compared to the Olivers had me fooled into looking for the wrong problem but I found it . C.A.R.E. posted the lower and upper position markings and I had already discovered my mistake earlier. Again,thanks to all who offered suggestions and help.

[rebelyell]

dunno what it's called, we called it a bearing scraper ... at a pal's shop he had a heavy, conical tool about 3" OD max that had maybe a dozen or so very sharp flutes.

We just held a rod assembled w/ both shells in hand ... and hand-turned the tool into the shells ... that tool chamfered the bearings/shells. Quick and dirty but it worked Very well. Turned low-buck P shells into chamfered shells in a skinny minute.

[Superstock]

Is .020"clearance a safe number to run your bearing away from the crank radius?

[fabr]

My opinion is that the bearing oil clearance is all that needs maintained minimum between shell and any contact point with radius. Really no such thing as too much.

[fabr]

A little birdie reminded me of something I think I should add to the above. There is not such a thing as too much so long as the oil hole is not too close to bearing edge to the point oil pressure would bleed off excessively. Thank you birdie.