Federal Mogul "A" series bearings. [Archive] - Chevelle Tech

: Federal Mogul "A" series bearings.


LeLynn
Sep 12th, 07, 2:21 AM
Hello everyone, I have a question about Federal Mogul's "new" aluminum bi-metal -A- series rod and main bearings. As you may have read in an earlier post of mine, I am building a 462 inch big block Chevrolet for my pickup. I have since traded my piston off to a friend at work and purchased a set of H426CP40 pistons that should net right at 9 to 1 compression ratio. My question is this. I got the rotating assymbly back from the balancing shop today "Again" and began to lay things out for reassymbly tomorrow. My neighbor came by to look at things and noticed that I was using bi-metal bearings. The bearings I am using as made my Federal Mogul and they are there "A" series. They are made of aluminum,tin and silicon rather then lead and babit like many other bearings on the market. My neighbor claims that these bearings are "Known to cause nothing but problems". I personally have not used them before, but saw no problem with doing so. Does anyone have any good/bad stories to tell about these bearings? I am affraid that if they do have a bad rep, I will have to replace them and send the rotating assy off AGAIN for re-re-rebalancing. I hope all is well with them, but would REALLY appreciate any input I can get. I will not be putting the engine together untill I hear the good or bad new. Better to wait to assemble it then to have an engine failure later on down the road. Thanks for all of your help.

Tom Mobley
Sep 12th, 07, 4:05 AM
they're an economy style bearing, not a source of problems that I know of.

Why would you re-balance an engine because of a bearing change? The weight differences between bearings are not significant on a 2000 gram bobweight.

ToyzRMe
Sep 12th, 07, 4:12 AM
I'm hoping Mike (Wolfplace) will jump in here with his opinions, but till then, I'll offer this.

The good old GM Delco-Moraine "400" bearing was an aluminum bi-metal bearing, and that bearing was widely used in the '60s and '70s. I used the hell out of them myself in 396/427 hi-po Big Blocks, and they held up very well for me.

The "400" bearing was quite a bit harder that a babbitt-overlay tri-metal bearing. The aluminum construction didn't allow much embeddability if you got a little crud between the crank and bearing. But, the factory hi-po forged steel cranks we were using back then were Tufftrided from the factory, which left a VERY hard surface.So, the hard bearing didn't beat up the crank surface too much because the bearing, even though it was harder, was much softer than the crank surface. But, you needed to be sure to maintain a CLEAN oil supply, and block off the filter bypass.

Now, when I rebuilt one of those engines, if I had to have the crank turned I'd use a tri-metal beearing because the turning removed the very thin Tufftriding layer and exposed the softer material underneath. Or else, I'd have the crank re-nitrided after turning and go back with the DM "400" bearings, just depending on the application.

I've run the old FM AP-series bearings in my 455 Olds engines as recently as the early '90s. Even using them on reground cast cranks, they worked very well for me. Alot of guys didn't like running them on reground cast cranks, but I put over 1100 passes on my last 455 Olds race engine before I sold it to a street guy. It held up fine for 2 more years, until his car got stolen.

The aluminum bearings are just not as forgiving of dirt or easy on the crank as babbitt-overlay bearings. But, IMHO, they're "tougher" than a tri-metal bearing. So, take steps to insure a clean oil supply at all times, which you should do anyway.;)

Mike, feel free to jump in here and correct me if you feel it's necessary!

Randy

LeLynn
Sep 12th, 07, 12:51 PM
Thank you toyzRme. I had never heard any real problems with the aluminum bearings. It is nice to have a little background on them. I will be sure to keep the enigne build clean of any debris. I am a little affraid to block off the oil bypass. I will be driving this engine on the street weekly. That includes winter driving. I have the block off plugged in the small block in my Nova and if I fire the car up when it''s 55-60 degrees outside the oil pressure is VERY high ((90-95 psi). I have no real need to drive the Nova in the winter so I don't, but if I had to, I would worry about the high oil pressures on cold start up. Is there any other options when running aluminum bearings on a cast iron crankshaft, other then blocking off the bypass. I already change the oil in all of my cars at 3000-3500 miles and use nothing but Wix filters. Will this still cause bearing problems provided the engine build is kept VERY clean and the oil is changed on a regular basis if I do NOT block off the bypass?

engineguy
Sep 12th, 07, 12:55 PM
The F-M aluminum bearing is a low-cost item, designed specifically for the production rebuilder market. "Most" OEM automotive engines are currently being produced with aluminum bearings based on cost reductions and they seem to hold up quite well in most cases.

Since you already have the F-M bearings, I would go ahead and use them. You would definitely want to use a performance bearing of some sort if you were using an aftermarket crank with large fillet radius and/or rods with dowell pins. In just about all instances the standard variety engine bearings will work pretty darn well in street/strip performance engines as long as clearances are correct, eccentricity is acceptable, engine was assembled and kept absolutely clean internally and oil the engine has oil pressure at ALL times. Remember, once the engine is started the bearings ride on a wedge (film) of oil therefore the bearing material/surface is of secondary importance.

ToyzRMe
Sep 12th, 07, 1:01 PM
Here's an option.

The filter adapter, the part the oil filter screws onto, bolts into the filter pad. You could make up one that's blocked off, and one that's not.

For initial fire-up and for break-in, use the blocked adapter. No matter how clean you assemble, you'd be amazed at how much crap ends up in the filter after the initial fire-up and oil change. Even the second oil change nets alot of junk sometimes.

After a couple oil changes, switch the adapter over to the unplugged one, and you should be OK.

Randy

Wolfplace
Sep 12th, 07, 1:54 PM
I'm hoping Mike (Wolfplace) will jump in here with his opinions, but till then, I'll offer this.

The good old GM Delco-Moraine "400" bearing was an aluminum bi-metal bearing, and that bearing was widely used in the '60s and '70s. I used the hell out of them myself in 396/427 hi-po Big Blocks, and they held up very well for me.

The "400" bearing was quite a bit harder that a babbitt-overlay tri-metal bearing. The aluminum construction didn't allow much embeddability if you got a little crud between the crank and bearing. But, the factory hi-po forged steel cranks we were using back then were Tufftrided from the factory, which left a VERY hard surface.So, the hard bearing didn't beat up the crank surface too much because the bearing, even though it was harder, was much softer than the crank surface. But, you needed to be sure to maintain a CLEAN oil supply, and block off the filter bypass.

Now, when I rebuilt one of those engines, if I had to have the crank turned I'd use a tri-metal beearing because the turning removed the very thin Tufftriding layer and exposed the softer material underneath. Or else, I'd have the crank re-nitrided after turning and go back with the DM "400" bearings, just depending on the application.

I've run the old FM AP-series bearings in my 455 Olds engines as recently as the early '90s. Even using them on reground cast cranks, they worked very well for me. Alot of guys didn't like running them on reground cast cranks, but I put over 1100 passes on my last 455 Olds race engine before I sold it to a street guy. It held up fine for 2 more years, until his car got stolen.

The aluminum bearings are just not as forgiving of dirt or easy on the crank as babbitt-overlay bearings. But, IMHO, they're "tougher" than a tri-metal bearing. So, take steps to insure a clean oil supply at all times, which you should do anyway.;)

Mike, feel free to jump in here and correct me if you feel it's necessary!

Randy
=
Can't add much to that :thumbsup:
The tri metal bearings (Clevite 77, ACL H series etc) are my choice as they are more forgiving to crap but there is nothing wrong with the FM "rebuilder bearings" in a mild build like this
But they are not real forgiving to foreign material.
And you would be amazed at the amount of crap left in an engine after "cleaning" that 200 oil seems to find & wash out not to mention no matter how good you think machined surfaces are they ain't smooth & there is going to me some "break-in" with them.

The first filter & oil change is usually pretty ugly
The second ain't much better
Drain your oil after about 30 minutes of break-in while it is still hot & go look at it in the sun,,,
If you have not done this before it may scare the crap out of you,, :D

Tom Mobley
Sep 12th, 07, 10:04 PM
LeLynn,

You don't need a HV/HP oil pump on a Chevy V-8. If you avoid their usage you won't have the 90 lbs cold pressure problem.

LeLynn
Sep 12th, 07, 11:32 PM
Well thanks to everyone for there input. I have taken the stock bypass valve and plugged it. I am going to get a brand new one this weekend from the local dealer to intall on the engine after the cam break in. I guess I will be using the aluminum bearings. At first I felt fine with using them, then after hearing the horror tory from me enighbor I was so affraid I almost went out and ordered a new set of Clevit bearings, but now after hearing from people with MUCH more experiance then myself I once again feel good about using them. I'll be sure to keep everyone updated once the engine is in the truck and running. Should be sometime late October. Thanks again.