Rod Bearing clearance with Carrillo Rods?

Talk and Tech about turbocharged 924/944/968 cars
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Cruise98
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Not sure on the bearing brand they were using. I am using the ACL's.

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michaelmount123
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There is no issue with Carrillo or any aftermarket connecting rod with respect to oil clearance. The issue relates to measuring and confirming the oil clearance. This is a (competent) machine shop job and should always be done when installing new or old rods. Measurement is half the job, correcting the clearance completes the job. Porsche tolerance on rod clearance is very wide, but the stacked tolerances between crank journal, rod bearing, and connecting rod can lead to issues. It's okay to trust, as long as you verify. Appropriate oil clearance is always the responsibility of the engine builder or assembler.

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four0four
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The machine shop should be able to dial in big end diameters for you!

Mostly just chiming in to note that I found it helpful to have one set each of standard and +.001 ACL bearings (mix and match for 0.5 thou over). Made it much easier to land on the clearance I was after.

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Cruise98
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The engine long block is already together. The shop checked the crank and the rods. Everything is within the factory specs. I checked the clearances as well before assembly and everything was good. So, the question is, should I take the pan off and swap bearings around until I get more clearance or not. If I could find the ACL 4B2475HX in stock from anyone, I would definitely take the time and increase the oil clearances now. Summit and many others can ship them in early January. I had been planning to have it running/driving before then, but I have spent so much time and money, what is another few weeks?

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michaelmount123
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...within factory specs... What does that mean? The factory rod oil clearance (ROC) spec is .0013" (way tight) to .0036" (way loose). You've not mentioned what your ROC is. I always shoot for .0025. Yes, you can certainly mix and match the standard and HX bearings to gain .0005, or gain .001 with all HX.

What is your ROC? You may be perfectly fine.

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four0four
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I think a lot of the storefronts that "stock" them end up just ordering from ACL. Summit both lists them and is transparent at least...

Failing that I have >50% of a set from when I rebuild my engine that I'm sure I could dig up and let go around cost.

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Cruise98
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michaelmount123 wrote: Thu Dec 07, 2023 3:57 pm ...within factory specs... What does that mean? The factory rod oil clearance (ROC) spec is .0013" (way tight) to .0036" (way loose). You've not mentioned what your ROC is. I always shoot for .0025. Yes, you can certainly mix and match the standard and HX bearings to gain .0005, or gain .001 with all HX.

What is your ROC? You may be perfectly fine.
Where did you get those specs. My little technical spec. booklet calls for radial play of .027mm - .069mm, which converts to .0011" - .0027" if my math is correct. I should have been more careful and asked more questions. I have assembled several engines but this is my first time with aftermarket rods. Thanks for your feedback.

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Cruise98
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four0four wrote: Thu Dec 07, 2023 4:33 pm I think a lot of the storefronts that "stock" them end up just ordering from ACL. Summit both lists them and is transparent at least...

Failing that I have >50% of a set from when I rebuild my engine that I'm sure I could dig up and let go around cost.
After I do the plastigauge thing, I may take you up on the offer. We will see how it goes.

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Cruise98
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I am not yet convinced this method is faster, but it does lead to a LOT more "while you are in there" moments. I was doing the ER Polybronze bushings anyway. Plus, I wanted to try something new. There are pros and cons to this, just like everything else.
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michaelmount123
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Cruise98 wrote: Thu Dec 07, 2023 6:46 pm
michaelmount123 wrote: Thu Dec 07, 2023 3:57 pm ...within factory specs... What does that mean? The factory rod oil clearance (ROC) spec is .0013" (way tight) to .0036" (way loose). You've not mentioned what your ROC is. I always shoot for .0025. Yes, you can certainly mix and match the standard and HX bearings to gain .0005, or gain .001 with all HX.

What is your ROC? You may be perfectly fine.
Where did you get those specs. My little technical spec. booklet calls for radial play of .027mm - .069mm, which converts to .0011" - .0027" if my math is correct. I should have been more careful and asked more questions. I have assembled several engines but this is my first time with aftermarket rods. Thanks for your feedback.
You still haven't mentioned what your rod oil clearance is.
Both my 944S/944 book and my 944S/944S2/944Turbo little books list the connecting rod/crankshaft radial play at ,034-.092 (.0013-.0036 in inches).

You're worried about too tight? What is your clearance??

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