Inliners International Forums General Discussion Engines BLOCK decking 2-for Dave C

Dave, I will get you more info soon...lets try a new Post here....I think its good for you to be doing this..I know the concept and will work with you on this if interested..i will be doing this procedure sometime myself- i looked into the feasibilty of this at 1 time ,thats how I know it will work..it may take longer than u want, but i can get this info....and u will have good compression...
Lee

Lee, this will probably make some people scream, but I worked in a machine shop in the 60's where we did this on performance built inlines all the time. If the block was to be finish milled .060, then we milled it to about .055. Then assembled the rods and crank. Then put it back on the mill(block assem. up side down) with two pistons sticking out and made the final cut. Then rotated the crank with two more sticking out and made another pass with the same setting until all 6 or 8 pistons were done. I know this gave zero deck height but they screamed and I never saw one come back with a piston problem.A lot of these were motors that were driven daily and raced on the weekends also. Paul


You may be disappointed if you fail --- but doomed if you don't try!!

Paul,

you milled the pistons while they were still inside the block??

Luis

I have seen it done that way In many shops around here and Back up home. To me it seemed like a odd way to go about it. I would have thought once the first piston had been milled it would have been just as easy to cut the Others down to match the first. But they did like you said They just rotated everything Pairs/two,s till everything was matched. }[oooooo]

hello...Thanks for comment Paul..glad to see you share your experience!!!!!!-and how this concept works/worked....
I just talked with my machinist-let me add this....
He said for a street/hot street application-with the 292 having such a large amount of casting from top of piston to 1st ring land, he stated he feels that probably having piston sticking out of block up to .030 is acceptable-based on a crushed head gasket of .038-.040...he does this on many engines and likes to see a minimum of .030 from head to top of piston for street applications....(what is cam lift??? this is also important-but not a big issue with 292 stock design pistons due to deep dishes)
So Dave c, try this if interested-Pauls procedure seems very safe too!!!!- take .060(more is ok too) and see where pistons are-then, if piston is out of block, see how much it is out-add .040 to it( for safty margin-thickness of head gasket)-here you can determine if you want to cut more off block and or piston....
I suggest you find a shop that is familar doing this type of work-Maybe you already know 1.....
Here is a great start.....
the way I do things i would probably take .100 off block-the 292 piston has alot there on the top-due to the fact the 292 has a 4.125 stroke ,a good amount of heat is built up in cylinder, cylindr walls, pistons and rings.....Using the moly type ring vs cast is a MUST in this procedure.....
let us know what you think...will this work for you?

Lee and others, if I were to do this today in my own shop, I would mill each individual piston on my mill(bridgeport) and mill the block sepatetly as Lee and larry are suggesting.I would then at least check the piston weights to see if they were still equal and re-balance if necessary. I was just trying to support Lee's theory and help him Make a point that there are still ways to make durable performance motors without spending big bucks.While todays vast inventory of amazing machines,equiptment and products are here,Ingenuity is still alive and well!! Paul

If you have a motor that has been bored .030 then milling the block .060 only bring the cylinder volume back to very close to equal. So unless the piston shape is changed, and the head and gasket are the same, the compression would stay very very close to the same as original when the block is milled .060 after being bored .030.In the case of dish pistons the depth of the dish will be less so there will be some increase but very minimal. Paul

Hey Paul,
As a machinist who actually machines parts himself on a daily basis, I'm always curious about "The old ways from the old days" . . . When they machined the block and pistons fully assembled as you described, what did they do in regards to corner radii on the freshly machined deck and pistons?

Obviously everything would have to be be torn down and cleaned thoroghly before re-assembly so the edges would be handled as a second op to remove the resultant flash from the machining operation but do you have a recollection of the approximate amount of corner break they used ?

I'm also wondering about the machining operation itself. . . which direction did they machine from so as not to have the finish effected by potential piston rock ? It almost seems you would have to cut it with a large head sweeping across the block instead of from one end so that the cutters would contact the pistons parallel to the wrist pins as they swept across.

Sorry for the detailed questions, that kind of stuff facinates me !

Thanks !

'Crockett

Moderator, please feel free to move this post if it constitutes a new topic.

Crockett, The proceedure I explained was "crude" indeed by todays standards.The motor was diassembled clean and reassmbled.The pistons were beveled something close to the original or what we thought would work. The cutting wheel on the mill a very large diameter( probably 18"-20") and had 30 or 40 cutters.The mill was a actually a large moving table with a frame work to suspend a head or block. The passes were made very slow and I am sure there was some "piston rock" even tho shims were install between the cylinder walls and skirts of the pistons being cut. Like I said "crude and time consuming" but successful in a time when it was near impossible to run out and buy what you wanted even if you had the money.--Paul