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ACL bearings - H or HX oil clearance?
Of those of you that have used ACL rod bearings, have you measured oil clearances of either one and can provide a little guidance on the resultant oil clearance?
Planning to use them for my 3.4 build based on the 3.2 bottom end. Nice to be able to choose the extra .025mm oil clearance but not sure I want it. Usually I have the rods re-sized after I have bearings in hand and have measured the clearance and get the rods sized to push the clearance in the direction I want. In this case I may use new rods so don't want to be farting around with that. I don't want to purchase two sets of bearings if I don't have to.
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02-24-2022, 04:49 AM
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Join Date: Dec 2003
Location: Australia
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I have used them before. They are a great high quality product. This is what i found on their site. FYI, i have made contact with them to see if they are able to to mains also for air cooled Porsches. They are looking into it so hopefully we will have a better product than what is on offer now.
The 'X' signifies the set will give an extra . 001” (0.25mm) oil clearance on a standard size shaft when compared to the H-STD set. The wall size of these HX-STD bearings is . 0005” (0.13mm) thinner than the H-STD bearings, in all other respects the HX set is identical to the H-STD set. Cheers Todd |
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02-24-2022, 11:56 AM
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Quote:
I do understand the difference between the bearings but what I don't know is the target oil clearance that each are manufactured to. In other words, are the "H" bearings giving you a .002" oil clearance and the "HX" giving you .003"? Or is it .0015" and .0025" etc. All the best, Jon
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02-24-2022, 02:29 PM
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Sorry I misread your post but that is a good question. Not sure i can help though.
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02-24-2022, 09:43 PM
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Join Date: Jul 2013
Location: Brisbane, Australia.
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Quote:
I've used them several times and have had zero issues with them. I usually get rods resized but it all depends on the tolerance to which they are sized. Bottom tolerance (from memory) is 58.00mm and top tolerance is 58.019. I have found that the ACL std bearings are fairly accurate and not "thinner" like glyco or AA Clevites. If your rods are sized to 58.010mm then the std bearings should give you a perfect 2 thou or 0.05mm clearance. If they size them closer to bottom tolerance then you might benefit from the larger clearance to get an extra 0.025mm total clearance or you can actually use 1HX shell and 1 STD shell to increase clearance by only 1/2 a thou.... yes, you can mix them. I'd probably wait till you have your rods so you know where they end up, so you know which set to buy. The good thing is, the ACL are quite affordable. If you take into account the rule of 1 thou/inch of bore, then technically, a 55mm bore is 2.16 inches, so you should be aiming for 2.1-2.2 thou for the 3.2 rods. I think if you end up with a clearance of 0.05(1.96thou) -0.06(2.36thou)mm you would be fine. Bear in mind, that your rod journals on the crank will likely vary by a tiny amount too. Are you using a bore gauge and micrometer to determine your oil clearances? Where do your source ACL bearings in the US? Curious to hear others experiences or suggestions.
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Always learning. www.aircooledporsches.com.au See me bumble my way through my first EFI and TURBO conversion! https://youtu.be/bpPWLH1hhgo?si=GufVhpk_80N4K4RP Last edited by mikedsilva; 02-24-2022 at 10:48 PM.. |
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02-24-2022, 10:42 PM
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Location: Australia
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^^^^^^^ Great answer Mike - very informative.
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02-25-2022, 12:21 PM
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Join Date: Mar 2001
Location: Wallenstein, Ontario, Canada
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Jon,
I used the standard ACL bearings in my 3.2 build and came up with 0.05mm of clearance. -Todd
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1989 911 Targa |
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02-25-2022, 01:13 PM
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Thanks Mike that's exactly what I needed and very helpful!!!
Normally I would measure the crank, the bearing shell thickness, and have the rods re-sized as a last step to ensure the clearance is to my desired spec, but in this case I am planning to go with new aftermarket rods and lose the control over the re-sizing step and the control it gives me over clearance. Yes I use a mic on the crank, a ball end mic on bearing shells, and a bore gauge in the rods to determine all this. Quote:
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02-26-2022, 05:25 AM
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Quote:
That's also very helpful. I meant to email you recently to find out how that all came together but lost your address and forgot your username! PM on the way.
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Heavy Metal! Part Deux - The Carbon Copy Project Heavy Metal https://tinyurl.com/57zwayzw (SOLD) 85 Coupe - The Rot Rod! AX beater Quality Carbon Fiber Parts for Classic 911s: instagram.com/jonny_rotten_911 |
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02-26-2022, 05:27 AM
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