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Cylinder bore honing - how often??

3098 Views 23 Replies 12 Participants Last post by  BBF612

I am rebuilding a 564ci BBC and am trying to decide if it is worth the time and money to get the bores re honed/new cross hatching... The engine was machined and honed last year (A very high-quality job I might add) and since then the engine only has about 20-30 1/4 mile passes on it. I am rebuilding for street usage and going from a high compression N/A setup to an 8.5:1 10psi turbo setup which means I will be going from a 44.9cc piston DOME to an 18cc piston DISH which is the reason I am debating new cross hatching to achieve a better piston ring seal. The hold up is that the current cross hatch is still in excellent shape, and I would hate to put it on a machine if it's not going to gain me anything. (See image below). What would you guys do if this was your build?

Part 2 to this question if I dare - JE told me if I gave them the weight of my existing pistons that they could add material to make the new pistons the same weight... With this said - would you guys re balance the rotating assembly? Note that the previous balance was done by the same shop whom I have great trust and does great work.

Thanks guys,

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Im quite surprised by these responses but im glad I posted the pic - I've gone to the same machine shop for probably 10-15 years and never had any issues at the track, but then again ive never tried doing a leak down test either with pressure or vacuum. I will this time around. Im going to be safe and just take the whole short block to a new shop and have it re balanced and honed per my new application. I did have a mysterious blue smoke issue at about 1000' down the track that was never determined, who knows could havwe been blow by this whole time! Any advice o what valiues are passable for a leak down test? I would like to test the assembled motor this time around... What are good vacuum numbers and over what duration of time?
P.S. not sure if i mentioned yet or not but the new motor will be a 8.5:1 564CI BBC with 10psi of boost ~ Shooting for 850HP street car - not sure if this info will have any effect on responses or not
Well...In NHRA Stock / Super Stock...if it’s hovering around 10% or more, You probably won’t bring it up amongst the crowd. Not that 10% is the end of engine life, it’s just not something to brag about. And I’m pulling my engine apart very soon as it’s LAUGHABLE leak down (on one bank only).
Stop Honing By The Numbers

Rpk, Rk and Rvk, where do these numbers come from? Why do they change so much and so often? Utilizing new software and measuring tools, you can move beyond the numbers and actually SEE the surface texture created in your honing process. Once you can see that texture, you can begin to modify your process (abrasives, loads, etc..) to create better performing and long lasting surfaces. Ed Kiebler and Lake Speed Jr. will show you the software in action and share their experiences of honing without the numbers, but still using a profilometer.

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