What is the correct procedure to over size the bores on L92 block .015" or .020" over to give 4.080" and 4.085" bores? Is honing .015" or .020" over acceptable or is boring .010" first necessary then finish lat .005" with hone for example? My L92 block has well centered sleeves. Reason for over bore is one cylinder has some scratches that need to be cleaned up that a .010" over will possibly not clean up. What stone grits should be used from initial honing to finish honing. Most likely will be using Mahle PowerPak with 1.0, 1.0, 2.0mm File Fit Performance Ring Set Included.

I posted a similar thread earlier but the title did not express needed info. Sorry if this is considered a double post

Thanks

 

This is an answer that your machinist must give you. You can’t walk in to your machine shop and tell them “this is what the consensus on the internet is, therefore this is what I need you to do”. Ask your machinist questions before demanding anything. If they have experience, they will be able to properly explain why they do what they do, and why it works for them.
Now having said that, I found while doing R&D work years ago, that the final cylinder wall finish is best when honing the final .006” minimum, .007” preferred. Most shops go .005” for final hone, and it works fine, but under magnification, the boring marks are still visible. I use a machinist who understands this and is still friends today with the owner of the R&D shop I was with in the early 90’s, so I don’t have to explain anything to my guy. The only complaints I get from him is when I bring in a sleeved block. The ductile is hard, and is tough on honing stones, so when I want .007” on my sleeved stuff, he knows he’s gonna be there a while. It’s a slow process.

 

Thanks Chev70elle.

My intent is to learn the proper proven methods how LS blocks are over sized and not "dictate" how the block will be machined. If standard iron block machining practices apply to LS cast in liner alum blocks then I have all the info I need.

 

I have honed .015" -.020" out of a block before using 123 stones (70 grit). I normally will bring the bore to .005" of the finished size with them and then switch to a 220 grit. I will take that to .0015" of the finished bore size, then switch them out to 280 grit to finish the bore. I will either plateau finish with a 320 grit brush or 5-6 strokes using a 400 grit stone with moderate pressure.

I would not consider setting up the block in a boring bar for less than a .015" cut.

 

Thanks Helicoil
That's good info.

 

I get where you're going, hone final finish and clearance for LS with certain rings are different than old school standards. I need the same info.
Helicoil - Thank You.

If you dont have a machinist you normally work with, find one that knows LS. Im going thru same thing, havent built an engine for 20 years, shops I used to use are 2 hours away.
Machining process and answers will vary depending on their shop and equipment VS internet lore.
Do they have torque plates for bore and hone for LS? Performance build - it matters to me.

If they're not answering your questions, or you dont like what your hearing. WALK - its your money.