New Scat Crank undersized ???

[user-612937456]

He doesn't need plasti gauge or snap gauges or inside mics, he has a dial bore gauge already, and he is more than qualified to use it.

Yes Plasti gauge is unreliable I have used it when it was all that was available. But you had to be really careful and use finess it is easy to mash distort and skew the actual measurements.

[BrazilianZ28Camaro]

Let me clear out the confusion friends. I should have said that I don't have the bearings in hand, I'll select them after measure everything to hopefully buy them once, because everything is explensive down here. I'm a die and tool maker at GM so precision measurements isn't a problem to me, although we "think" in milimeters overhere.

Wish I could have a set of standard main bearings to do a pre-assembly, but I don't.

Bap race is correct about the advertised main size versus the actual main size. I have measured 350 cranks and they're aways smaller than 2.45" at the mains, more like 2.4489-2.4490".

When I searched for the "real" 400 crank main size all the sources showed 2.650" then I assumed this is correct, but I'm aware it may be a bit smaller like the 350 real size journal is.

I guess I should have asked first what the 400 mains exact size is before assume it is undersized, (This is what I got for work way too much).

Now Modok wrote :

according to clevite the diameter spec is 2.6484-2.6493
bearing thickness .0955
housing 2.8406-2.8415


Then, the actual main bore minus two times the bearing thickness minus the journal size would run at only 0.0015" oil clearance, meaning I'd need .001" oversize bearings to have an aceptable clearance.

Modok, where you found these specifications? I couldn't find anything at clevite website?


Thanks for reply fellas, very valuable!

[modok]

I have a 2005 clevite bearing catalog sitting on top of the computer.

I believe you can download bearing catalogs in PDF form from Clevite, King, and ACL for free, if you go to their website and find it.

Clevite bearings I find are usually very close to the max wall they list, but sometimes they are .0005" thinner, there is always some variance in these things.
If you order one set of standard, and one set of the HX (.001 additional clearance), I believe you will be able to get the clearance you want.

[modok]

I found it, by google, keywords "clevite catalog pdf"
http://www.mahle-aftermarket.com/na/en/ ... logeb-10-0

[BrazilianZ28Camaro]

I have a 2005 clevite bearing catalog sitting on top of the computer.

I believe you can download bearing catalogs in PDF form from Clevite, King, and ACL for free, if you go to their website and find it.

Clevite bearings I find are usually very close to the max wall they list, but sometimes they are .0005" thinner, there is always some variance in these things.
If you order one set of standard, and one set of the HX (.001 additional clearance), I believe you will be able to get the clearance you want.

I'll download the catalog, thanks!

[Bob Hollinshead]

Let me clear out the confusion friends. I should have said that I don't have the bearings in hand, I'll select them after measure everything to hopefully buy them once, because everything is explensive down here. I'm a die and tool maker at GM so precision measurements isn't a problem to me, although we "think" in milimeters overhere.

Wish I could have a set of standard main bearings to do a pre-assembly, but I don't.

Bap race is correct about the advertised main size versus the actual main size. I have measured 350 cranks and they're aways smaller than 2.45" at the mains, more like 2.4489-2.4490".

When I searched for the "real" 400 crank main size all the sources showed 2.650" then I assumed this is correct, but I'm aware it may be a bit smaller like the 350 real size journal is.

I guess I should have asked first what the 400 mains exact size is before assume it is undersized, (This is what I got for work way too much).

Now Modok wrote :

according to clevite the diameter spec is 2.6484-2.6493
bearing thickness .0955
housing 2.8406-2.8415


Then, the actual main bore minus two times the bearing thickness minus the journal size would run at only 0.0015" oil clearance, meaning I'd need .001" oversize bearings to have an aceptable clearance.

Modok, where you found these specifications? I couldn't find anything at clevite website?


Thanks for reply fellas, very valuable!

A friend of mine built pro-stock motors for awhile and told me it was common practice to sand the backsides of bearings for a little more oil clearance when needed. I'd like to see a how-to article on doing this. Diego, hopefully some day there will be a way for people in your country to get parts at a realistic price!

[user-612937456]

according to clevite the diameter spec is 2.6484-2.6493
bearing thickness .0955
housing 2.8406-2.8415


Then, the actual main bore minus two times the bearing thickness minus the journal size would run at only 0.0015" oil clearance, meaning I'd need .001" oversize bearings to have an aceptable clearance.

Do I understand that you are looking for .0015 clearance on the mains? If so this is too tight. I always look for .0024"-.003" on a 400 sbc main. Some people like to set up the mains up loose at over .003"-.004". For the big three main stream motors and probably many others too, a general rule of thumb is .001"- .0013" clearance for each 1" of journal diameter. So a 2.650" journal should be .0026"

[Walter R. Malik]

Sounds like it could simply be an "OVER-POLISH" job to me.

Two "tenths" under the low limit on the rods and eight "tenths" under the low limit for the 1 through 4 main journals, (only three "tenths" under on number 5), is what most people actually WANT for a racing type build.

Simply use those .001" undersized bearings if you want less oil clearance.

[BrazilianZ28Camaro]

A friend of mine built pro-stock motors for awhile and told me it was common practice to sand the backsides of bearings for a little more oil clearance when needed. I'd like to see a how-to article on doing this. Diego, hopefully some day there will be a way for people in your country to get parts at a realistic price!

Hi Bob

I've seen that too, but I guess only little material can be removed before the bearing crush is compromised...

The imported parts are heavily taxed because the gov want to protect our national industry....But wait... nobody here make parts for V8s...so....

Thanks for the wishes my friend, we all dream with the day our gov will govern for the people and not for themselves.

[Dan Timberlake]

A friend of mine built pro-stock motors for awhile and told me it was common practice to sand the backsides of bearings for a little more oil clearance when needed. I'd like to see a how-to article on doing this. .......

I can't imagine that process creating an accurate, smooth surface, and that could mean not-so-hot heat transfer.

[BrazilianZ28Camaro]

Just an update:

I ordered the Clevite tri-metal H bearings PN# CB663HN1 for the rods and MS1038HX for mains. They should work.

Thanks

[Walter R. Malik]

Just an update:

I ordered the Clevite tri-metal H bearings PN# CB663HN1 for the rods and MS1038HX for mains. They should work.

Thanks

"X-tra" clearance main bearings ...?
Being that your finished "line hone" specs are also, 6 ten thousandths, (.0006"), UNDER the low limit it may work out.

[BrazilianZ28Camaro]

Just an update:

I ordered the Clevite tri-metal H bearings PN# CB663HN1 for the rods and MS1038HX for mains. They should work.

Thanks

"X-tra" clearance main bearings ...?
Being that your finished "line hone" specs are also, 6 ten thousandths, (.0006"), UNDER the low limit it may work out.

Exactly, .001" extra clearance on the mains.