Cylinder Hone Questions

[Bad Bob]

I recently picked up a Sunnen honing machine, and in the boxes of stuff that came with it was a portable AN style tool with 280 grit stones.

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1.Do I need different grit stones or multiple grit stones than this?
2. Can the cylinders be honed as is, or do they need a torque plate or other fixture?

[machineshopjohn]

what you have is a an style sunnen hone the stone that you have in the picture are stone that are for key-way or open port cylinders like two stroke motorcycle cylinders also the set you have as pictured are missing the guilds that go into the other holes it the square block that the stones are in...

the old sunnen numbers are an 100 an200 an300 an500 and they have also numbers like an201 an 301 and an501 these stones are for bigger bores then the std an numbers..

sunnen has dropped those numbers and have numbers like gy45j55 which is really confusing in as they have pulled back on taking care of the automotive industry and are using a lot of numbers from their industrial side of honing stones in the automotive industrial..

check their web site www.sunnen.com

go to the engine rebuilding engine part and look at stones they have a crossover for the numbers old and new
they also tell the grit of the stones like an100 course up to an500 fine think about it like woodworking

an100 rip the material out fast an300 med finish for like cast rings and an500 fine for moly rings they also go quite a bit finer also look on the sealed/power web site they will tell you want finish they want for ring seal then use the right stone set and plenty of honing oil

sunnen will not sell to you direct they sell only wholesale but there's lots of sunnen stones for sale on eBay hope this helps

[Bad Bob]

Thanks John. I did some looking in a Goodson catalog, and it showed the stone and guide set. I see some engines are honed with a torque plate to simulate the cylinder wall deformation after assembly. Are VW cylinders done this way, or honed as is?

[machineshopjohn]

I don't have deck plates for vw's, I do have them for Harley, Chevy's, Ford's and Chryslers',

I have a mounting plate from years ago for boring and honing corvair cylinders that we do in a CK10 sunnen machine , there are pistons avaibale in over size for corvairs but not for vw's, other than having them custom made J &E , Wiseco or one of the other customs piston manufactures out there..

I do increase the clearance in VW cylinders for turbo motors and do them on my sunnen rod hone with a mandrel that uses the same stones that I was telling you about... I do buy some stuff from Goodson and they are a very good company,
But i use mostly sunnen stones and oil in my machine because they are whats called graded stones and breakdown uniformly, and we can control the sizes that we want/or need...

Years ago when Dean Lowery was in Tucson, I used to install seats in big valve heads for him, He did some tests on VW engines and big bore cylinders 92mm and found that even with new straight cylinders that they distorted enough to get 18 to 22 percent leakage past the rings , in a running motor because they were thin enough to flex so I don't think that deck plates will help much on them..

[66brm]

I have seen torque plates for cylinders but they were a custom made fixture as they applied torque to the cylinder in the same way they are clamped to a case ie top of the cylinder to the case register. They were used to hone a local machine shops cylinders for their company drag car/test car. The cylinders were checked before and after honing and it was surprising how much deformation occurred, I always wondered about the effects of heat in a built engine after this treatment

[tencentlife]

sunnen will not sell to you direct they sell only wholesale

I'm a sole proprietorship with a tax number in my state but I'm just a jobber, not a dealer or machine shop, but Sunnen was happy to sell to me and never asked anything about my business status. They are very helpful with figuring out what you need and what parts from the catalog work together, which is key because learning that yourself from the catalog can be pretty confusing. I looked and looked at Goodson and Cyl.Head Supply for the components I needed and finally broke down and called Sunnen. They were so helpful, and the prices no higher than the other dealers', now I just call Sunnen direct whenever I need anything.