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Rawze · 04-16-2022, **(Subject: Block cutting )**

(04-16-2022 )dericson Wrote: What’s going on crew?

I had some questions on block cutting. Just got certified to cut blocks through Cummins. Haven’t used the skill in about 4 months since getting certified, but recently got tasked to cut two ISC/L blocks. Was able to work through getting them cut and shimmed correctly. Aside from the obvious details like mic’ing depth and triple checking, any tips? Sure is a slow process. I understand Cummins still promotes the brass shims but I have been seeing a lot on convo about the stainless shims. What are your thoughts in shin integrating? Obviously stainless would hold up better over time vs brass. But would any of you folks be worried about the hardness of a stainless shim being less forgiving In terms of “squish” vs a brass shin? In regards to cut depths, I know the standard isx block takes two sizes, but the isl takes up to 5 sizes, when cutting, what are thoughts on shim stacking? Clearly Cummins doesn’t believe in stacking, just curious what other experienced cutters think. Obviously Cummins wouldn’t practice this because or warranty issues. When it comes to cut spec, I try and cut depth to max out top line protrusion. Not as much of a worry on the ISL blocks, but recently Cummins changed the liner protrusion spec on the isx from 7 to 14 to 7-12. I’ve heard of a lot of guys still cutting to max 14 or even higher to like 15-16, thoughts? Any advice appreciated, trying to dial in these cuts and plan accordingly.

in reference to the ISX's.. I am not as familiar with other model engine liner heights specifically ...

throw that training garbage in the trash can. - Someone is smoking a creak-pipe if they think that 0.007" on an ISX is ok.. or even 0.012" for that mater.. THAT IS TOO LOW FOR AN ENGINE THAT HAS ANY KIND OF AGE ON IT@@@... IT DOES NOT EXTEND THE ENGINES LIFE ONE GODDAMN BIT BY SETTING THEM THAT LOW!!!.. AND ONLY CONTRIBUTES TOWARDS THE TRUCK OWNER HATING HIS ENGINE WHEN THE HEAD GASKET LETS GO AGAIN IN 2-3 YEARS ,,... THIS IS EXACTLY WHY THOSE OEM STEALERS$ITS AND CERTIFIED SHOPS ARE THE MOST HORRIBLE PLACES TO TAKE YOUR ENGINE TO!!!..--- stop drinking their cool-aide.. your only going to accomplish proving how bad those oem places really are!

Personally, I prefer brass shims. They are hardened brass.. not soft brass. - You loose about 0.001" of crush/compression when using them and that is perfect actually. (on the ISX's) Set the liner height to 0.016" and it will crush down to 0.015" by the time the head is fully torqued, then re-torqued the next day, a second time like it should be done. - It makes for a second seal against seepage when it crushes, they are far more forgiving for heat expansion cycles over time, and the brass expands at a greater rate than the cast iron with higher heat loads.

I have never seen an issue or a liner dropping or letting go prematurely because of the use of brass shimms when the liner height is set to 0.015"+, and head was torqued as recommended on this forum, instead of the shortcut method in the books. Not even with higher HP, 750+ applications, unless the engine was abused in some way to cause it.

Therefore, here are my views/thoughts on this...

Stainless shimms are far more rigid and it requires the block be cut where the liners are 0.001" lower than you can set the brass shim height to. This is also harder on the block over time with heat cycling and the component that suffers fretting (or potentially cracking) the most is that engine block when using stainless shimms. Makes it far more difficult to correct if there is another inframe+counter-boring needed the next time around.

The only time stainless should really be used as a first choice is when there is a special need for it. Like a casting defect, cracked mid-stop to strengthen and support it, of if more then 0.032" of shim thickness is needed because someone cut the counter-bores too deep and its better than scrapping the whole block. Brass shims should ALWAYS be someone's first choice, regardless of power levels, unless there is a specific need for stainless due to some defect, etc.