Main bearings 1/2 groove or 3/4 groove

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Main bearings 1/2 groove or 3/4 groove

Post  Dave De on August 26th 2016, 10:25 pm

Where have the 3/4 groove bearings gone? All I see are 1/2 groove.
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Re: Main bearings 1/2 groove or 3/4 groove

Post  Lem Evans on August 27th 2016, 9:30 am

FM 134M were 3/4. Have they gone to 1/2?

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Re: Main bearings 1/2 groove or 3/4 groove

Post  Dave De on August 27th 2016, 10:18 pm

I posted too soon. This comes from re-ordering Clevite H series mains and they were 3/4 groove but now are 1/2 groove. For some reason I tend to stay away from Speed Pro and yes they are still 3/4 groove. Looking up King bearings the H series are 3/4 groove.
Do I need 3/4 groove?
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Re: Main bearings 1/2 groove or 3/4 groove

Post  rmcomprandy on August 27th 2016, 11:51 pm

That is all a personal decision ...
A full groove will help a deficiency in the rod bearing / journal union to be better but, a half groove, (actually 165 degree groove which nobody makes), will help the load carrying capability of the main bearing oil film.

A 3/4 groove was an attempt to get the best of both worlds. So, it really depends upon the actual working atmosphere of all the bearings and where you think needs the biggest "helping hand"..

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Re: Main bearings 1/2 groove or 3/4 groove

Post  Dave De on August 28th 2016, 7:01 am

rmcomprandy wrote:That is all a personal decision ...
A full groove will help a deficiency in the rod bearing / journal union to be better but, a half groove, (actually 165 degree groove which nobody makes), will help the load carrying capability of the main bearing oil film.

A 3/4 groove was an attempt to get the best of both worlds. So, it really depends upon the actual working atmosphere of all the bearings and where you think needs the biggest "helping hand"..

Aren't 385 series engines more prone to rod bearing failure over main bearing? This would give the 3/4 groove more application? I am basing that on a failure of mine years ago with a D9 block. Now A460 block with priority main may not be an issue for me. Maybe this is a non-issue to get oil to the rod bearings 50% more time duration?
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Re: Main bearings 1/2 groove or 3/4 groove

Post  rmcomprandy on August 28th 2016, 11:02 am

Dave De wrote:
rmcomprandy wrote:That is all a personal decision ...
A full groove will help a deficiency in the rod bearing / journal union to be better but, a half groove, (actually 165 degree groove which nobody makes), will help the load carrying capability of the main bearing oil film.

A 3/4 groove was an attempt to get the best of both worlds. So, it really depends upon the actual working atmosphere of all the bearings and where you think needs the biggest "helping hand"..

Aren't 385 series engines more prone to rod bearing failure over main bearing? This would give the 3/4 groove more application? I am basing that on a failure of mine years ago with a D9 block. Now A460 block with priority main may not be an issue for me. Maybe this is a non-issue to get oil to the rod bearings 50% more time duration?

The quality and strength of the parts, (including oil thickness and clearances), used in a rotating assembly will change the point of the "weak link" and what will be best for THAT situation.

The only way to actually know is to run it within the environment it will get used, take it apart and inspect the condition of everything and re-assemble it all accordingly.

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Re: Main bearings 1/2 groove or 3/4 groove

Post  away on September 7th 2016, 4:17 pm

Run FULL GROOVE period. Protect them rods!! I run full groove in all my stuff and just went 5.53 @124 in the heat this past weekend!

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Re: Main bearings 1/2 groove or 3/4 groove

Post  Carl on September 7th 2016, 5:24 pm

It doesn't make a big difference in most applications.

I run half groove, and went 150.7 mph in the standing mile last weekend.

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Re: Main bearings 1/2 groove or 3/4 groove

Post  AZFairlane on September 7th 2016, 8:48 pm

Way to go Carl, is that the first time over 150mph?
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Re: Main bearings 1/2 groove or 3/4 groove

Post  Carl on September 11th 2016, 8:35 am

AZFairlane wrote:Way to go Carl, is that the first time over 150mph?

Thanks. It's a new personal best. The land speed guys call it "the 150 club".

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