Bearing clearance king racing

[Jay_Kay]

Hi,
I'm rebuilding my engine and am currently measuring all of the clearances.
I'm using king racing bearings and catcam rods.

I've measured the crank at 1.88995"
The conrod without bearing at 2.0313"
The conrod with bearing at 1.8933"

giving me a clearance of 0.00335" which is way higher compared to what I need to be aiming for.
Is this due to being "race" versions I've got an extra 0.001" of clearance?

WI'll I have better luck trying a plain standard bearing?

 

[Touring_Rob]

What are you measuring with and how.

I install bearings and torque up caps, then use a bore gage to get a measurement at 3 points around a bearing. Usually your interested In the center.

Then use micrometer on journal again at three points to check for ovality.

I do that across all journals and then swap bearings about until I have a uniform clearance within spec. I've had to buy several sets of bearings in the past to achieve target.

Plastigauge is a good sanity check too.

 

[Jay_Kay]

I'm using a micrometer for the journals. Like you said measuring at 3 points. The ovality was next to nothing on them.

Conrods I'm using a cmm machine at the moment. All torqued down to spec everytime.

I'll use a bore mic for the main journals.

I've ordered new plain nothing fancy bearings. As I've remeasured everything twice and it has to be the bearings are giving me 0.001" extra clearance being branded as "race".

 

[gambit]

Following with interest as need to build my engine myself for first time and yet to decide on bearings for PEC rods.

 

[NorthloopCup]

I’ve seen more engines fail with ‘race’ spec bearings fitted than I care to remember. They do have increased clearance on them, but that’s because they’re hard. Once scuff and you’re on the way to engine failure.

On the R3 maxi engine I built for myself, I used standard mahle bearings. Still on the go now to my knowledge and not been opened up.

There’s a lot to be said about running standard spec bearings and just swapping them out sooner imo. But I also do different things to improve the f4r engines for oil supply/pressure which obviously helps the job along.

Have you had the mains checked for alignment as well?

 

[NorthloopCup]

Following with interest as need to build my engine myself for first time and yet to decide on bearings for PEC rods.

Get the pec rods checked for ovality mate. They’re quite often not the best. Check the gudgeon pin clearance measured as well - again another area that’s not the best.

I will only use Saenz rods, or custom made rods in the f4r builds I do now.

 

[gambit]

I’ve seen more engines fail with ‘race’ spec bearings fitted than I care to remember. They do have increased clearance on them, but that’s because they’re hard. Once scuff and you’re on the way to engine failure.

On the R3 maxi engine I built for myself, I used standard mahle bearings. Still on the go now to my knowledge and not been opened up.

There’s a lot to be said about running standard spec bearings and just swapping them out sooner imo. But I also do different things to improve the f4r engines for oil supply/pressure which obviously helps the job along.

Have you had the mains checked for alignment as well?

What big end bearings do you prefer?

 

[Touring_Rob]

I'm using a micrometer for the journals. Like you said measuring at 3 points. The ovality was next to nothing on them.

Conrods I'm using a cmm machine at the moment. All torqued down to spec everytime.

I'll use a bore mic for the main journals.

I've ordered new plain nothing fancy bearings. As I've remeasured everything twice and it has to be the bearings are giving me 0.001" extra clearance being branded as "race".

Good brand ones? Its not hard to lose or gain a thou with poor measuring equipment - looks like your tolerances would be acceptable in an R3 though so I guess the race bearings really are adding that. I wouldn't personally run them with those clearances.

 

[Touring_Rob]

I’ve seen more engines fail with ‘race’ spec bearings fitted than I care to remember. They do have increased clearance on them, but that’s because they’re hard. Once scuff and you’re on the way to engine failure.

On the R3 maxi engine I built for myself, I used standard mahle bearings. Still on the go now to my knowledge and not been opened up.

There’s a lot to be said about running standard spec bearings and just swapping them out sooner imo. But I also do different things to improve the f4r engines for oil supply/pressure which obviously helps the job along.

Have you had the mains checked for alignment as well?

I was under the impression that the King race bearings were softer than lots of modern OEM as they still use all the 'good stuff' that manufacturers can't (copper - lead - tin). The BMW boys recommend them often for the S54.

 

[NorthloopCup]

What big end bearings do you prefer?

The ones I have personally used are Mahle with the tags.

I was under the impression that the King race bearings were softer than lots of modern OEM as they still use all the 'good stuff' that manufacturers can't (copper - lead - tin). The BMW boys recommend them often for the S54.

Yeah I think they’re softer than the likes of ACL, but they’re definitely not softer than OE items mate.
Well they probably w**k over them because folklore dictates that bmw got the clearances wrong on the S54 which is why the rod bearings fail. The earth is also flat.

 

[luckfilewalker]

The ones I have personally used are Mahle with the tags.

Yeah I think they’re softer than the likes of ACL, but they’re definitely not softer than OE items mate.
Well they probably w**k over them because folklore dictates that bmw got the clearances wrong on the S54 which is why the rod bearings fail. The earth is also flat.

Hello @NorthloopCup, I have started a conversation with you about this subject, can you help me with those questions please? Thanks a lot