Viprklr

iTrader: (5)

On the back of my main bearings is stamped .0006. I calipered the bearing thickness at .093. These don't appear to be stock sized mains so what size do I need to get? I don't see anything at summit that states .0006.

TransAM Joe

iTrader: (6)

If your crank journals are standard, then the bearing will need to have STD stamped on them, or if they are turned under they will need to match that size like -.010, or -.020. take it to a machine shop and have them measure it and get you the right main bearings.

Sonix

iTrader: (1)

.0006" ? That's a weird one.

Is this a stock crank from your engine? You can mic it and see what it's diameter is, and if it's ovalized at all. Probably want to get it turned if it's got 100,000 miles on it sorta thing, then just get .010" bearings.

ede

measure your crank then you'll know what size bearings to get, or if it needs ground undersize.

Viprklr

iTrader: (5)

I don't know if it's the stock crank. Apparently whoever owned it before me has already been into it.
I'll measure the journals. What's stock diameter?
When I showed the machine shop the bearings he said they were "half-under". Does that clarify anything for you?

Viprklr

iTrader: (5)

Searching around on here it looks like 2.45 is a stock diameter main journal. I mic'd a few of mains at 2.45-2.51. Maybe it is a standard size but whoever owned it before wanted it a bit tighter.
The car has 93K on the odo. It sucks not knowing anything about the parts in an engine that's obviously been opened up before.
I believe this car was even previously running nitrous. When I got it there was a fishy looking switch under the go pedal that would only click on at full throttle.
So should I get this turned or get standard bearings?

sofakingdom

iTrader: (1)

There's no such thing as bearings manufactured in .0006" undersize. Whatever the markings are, they don't mean the size.

Bearings in .001" undersize are unusual enough. I don't think I've ever used any in all my days, and I've only taken a couple out of motors I was building (mostly obvious hack repair jobs, probably warranty situations). As far as I'm concerned, if a crank is worn to the point that it doesn't fit the bearings, it's time for a regrind or replacement, and the correct size bearings in a standard undersize (or no undersize at all). But that's just me.

2.51" is .060" larger than the stock main journals of that crank. That's 100 times larger than the interpretation you're trying to give those markings, and in the opposite direction besides (markings on the bearings are for cranks that are SMALLER than stock, 2.51" is LARGER than stock). The journals AREN'T that size. Sounds like you need a new micrometer or something. The PO certainly didn't make that sort of a change. That would require welding about 1/32" of material up onto the journals. Didn't happen.

A .010" under crank would have journals of 2.440".

Nitrous, or mileage, or whatever sort of a WOT switch that might be, wouldn't have anything to do with this.

Get a good quality mic or caliper, and learn how to use it. Then bring us back some accurate numbers. Leave the guesswork about the engine's history out of it, it is not relevant.