rjw

iTrader: (3)

I just started a trial fit of main and rod bearings and all of my NEW Federal Mogul (Speed Pro) main and rod bearings are out of spec.

Checking was done with micrometer and dial bore gauge (accuracy of less than .0001")

Example: With my new rods, all the big end bores were round to within .0001".

Installed bearings and torqued rods and bearing clearances measured .002" up/down, .0032" 45 degrees, .0043" near parting line.

That's over .002" oval. All rod bearings were around the same, and main bearings were just as bad.

Just thought I would share that with anyone considering using these or buying an engine with these bearings.

I spoke to a very reputable builder who confirmed that these bearings were not very accurate as far as O.O.R.

SO I am dumping them and getting Clevites...

Anyone else have this type of problem?

427

iTrader: (3)

All bearings are made that way, they run more clearance at the parting line. Check your clearance vertical, this is the measurement that matters.


Kurt

Jason99T/A

iTrader: (21)

Kurt is exactly correct. What you are seeing is bearing eccentricity. Connecting rods are subjected to high inertia loads. The weight of the piston, rings, wrist pin,etc. are all pulling on the rod cap, especially at the end of the exhaust stroke. This tries to stretch the rod and pulls the big end out of round, which causes it to close in at the parting line. This is where the bearing eccentricity provides extra clearance to let the rod flex without having the bearings contacting the crankshaft.

Some applications require more or less bearing eccentricity. This is why when a motor is torn down, it is very important to study the wear pattern on the bearings. This will tell you if you had too much, too little, or just the correct bearing eccentricity.

Jason

rjw

iTrader: (3)

I've built 100's of small block and big block chevy's as well as chrysler hemis, sport compacts , etc. and NEVER seen 2 to 2 1/2 thousandths eccentricity on a main or rod bearing, unless the housing was out of round.

I accept up to 1 thousandth, period. In most cases it is less.

Even the stock OEM bearings that came out of the engine, were better than these, at no more than .0015" ECC in either the new or old rods.

I have normally used Clevite bearings, but decided to try the F/Moguls in this case.

BTW, to each his own, but NO one has ever blown up a bottom end that I built, and in the 70's and 80's, I built MANY and for both race and street applications.

I am astonished to hear that people build these things with 2 thou in the vertical and 4 1/2 at the parting line.

Maybe I'm a dinosaur

JMHO

ty_ty13

iTrader: (42)

i'll just tell you that the guy above "427" has done more with GM platforms and motors than youll ever dream.... i'd take his and the W2W shops advice... hell they help build alot of GM's stuff

rjw

iTrader: (3)

Ok, I am open minded and curious.

Checked another one today and it is eccentric by over .0025".

What application NEEDS over .0025" eccentricity by design?

And for an FI street application, would you use this?

Will Cevites be less eccentric?

Cstraub

iTrader: (1)

Depending on which bearing type you have the eccentricity will vary. This may help
http://www.clevite.com/techbulletins/CL77-1-205R.pdf

rjw

iTrader: (3)

First, I apologise for bashing Fed/Mogul. I am sure than many use their products with good results.

I may just be too picky, but I am curious about how much eccentricity is too much

Cstraub

iTrader: (1)

rjw,
Start on page 57. This should give you what you want.
http://www.clevite.com/publications/6-101-02.pdf