another bearing? 1/2,3/4,full groove...?

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another bearing? 1/2,3/4,full groove...?

Post  torino501 on August 29th 2013, 4:22 pm

not only are there the different bearing materials to deal with and the perfect clearance...? when or in what appliaction do you use a 1/2 groove,3/4 groove or even a full groove bearing? and with what pump.

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Re: another bearing? 1/2,3/4,full groove...?

Post  68galaxie on August 29th 2013, 4:36 pm

I think some are afraid to answer your question - just in case they don't know the "correct"answer.

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Re: another bearing? 1/2,3/4,full groove...?

Post  68galaxie on August 29th 2013, 4:36 pm

68galaxie wrote:I think some are afraid to answer your question - just in case they don't know the "correct"answer.

Just Kidding!

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Re: another bearing? 1/2,3/4,full groove...?

Post  kim on August 29th 2013, 5:10 pm

stock 460 build, 1/2 grove is fine, intent of the engine is truck/heavy sedan application, Most stock type applications wouldn't see RPM over 3000 for peak, and would spend most of their lives at idle to about 1800 RPM.

The 1/2 grove bearing is great for ensuring there is a sufficient oil buffer in the main bearing at load. Its detriment is lack of feed to the rod, so the rod bearings get a pulse feed.

The full grove main bearing will facilitate continuous oil flow to the rod bearings, the centripetal forces of the rod bearings, tend to pull oil and will "suck" the oil from the main if insufficient feed is supplied. The detriment of the full grove is a lack of support in the main bearing. Using smaller rod bearings has allowed us to not worry so much about feeding oil to the rods?

3/4 grove, more oil to the rod bearings. Still an area of high pressure cushion in the main bearing.

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Re: another bearing? 1/2,3/4,full groove...?

Post  Lem Evans on August 29th 2013, 5:18 pm

I've used the ACL, F-M/Speedpro and King 3/4 groove main bearings with good results. I see no reason not to use the 3/4 style.

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Re: another bearing? 1/2,3/4,full groove...?

Post  rmcomprandy on August 29th 2013, 7:18 pm

torino501 wrote:not only are there the different bearing materials to deal with and the perfect clearance...? when or in what appliaction do you use a 1/2 groove,3/4 groove or even a full groove bearing? and with what pump.
It all depends what you believe to be the "weakest link".

Pertaining to the mains:
A 1/2 groove main bearing, (actually only 150 degree groove according to the SAE testing with passenger casr engines), will supply the greatest amount of main support, as anything more will simply pass more oil across the bearing face.  
The amount of oil going across the face is important to surface cooling of that face; which in short means that really tight main clearances NEED a longer groove, the question is, how long is long enough.

Pertaining to the rods:
The longer the groove in  the main bearing, the more oil will be directed toward the rod bearings; also, the tighter the main bearing clearance, the more oil goes to the rod journal and bearing. The clearance at the rod will control the amount of oil throw-off and the thickness of the oil wedge there and somewhat at the main bearing. Also, the lesser or more total oil thrown-off will control the oil temperature up to a point.

As you should be able to see ... it is all a compromise in order for the engine builder to get the the lower end specifications he wants.
Almost every engine builder I know is looking to satisfy the part where he believes needs the most attention and works back from there.

Your choice...

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Re: another bearing? 1/2,3/4,full groove...?

Post  torino501 on August 29th 2013, 9:51 pm

Wow so much to consider when building the bottom end? OK randy... give me a scenario where you would use a 3/4 bearing a 1/2 groove and a full groove. Towing?street/strip? Full race? Damn so many choices?

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Re: another bearing? 1/2,3/4,full groove...?

Post  rmcomprandy on August 29th 2013, 11:59 pm

In a Big Block Ford - Presuming around 600 lb/ft of flywheel torque with a cast crank using rod bearing clearances of .0022" and NO vacuum pump ... 1/2 groove main bearings with main clearances of .0025" to .0032". Maybe a bit more groove length, (or slightly larger clearance than with the other 4), on the thrust bearing, especially if it has a clutch. That would be SAFE.

Work back from there. There are just to many scenarios to go into it.  That is why people take the word of an engine builder they trust and go with it; (most of the time it will be SAFE, not necessarily completely correct for that application). This all presumes decent bearing manufacturer. One thing I didn't mention before is that the bearing installed ellipticity measurement has an effect upon what is used, also.
The end user and how that engine will be treated and the perceived maintenance has a large input upon EVERYTHING.

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