Anybody have access to a cummins

SVcummins · May 25, 2021

Manual for a b series? 1998 manufacturer date 24 valve
whats the minimum clearance spec for the connecting rods ?
I can find Max but no minimum

rustred · May 25, 2021

what are yours measuring? .0015 is a kind of a standard thing for new, but yes good to know, dont want to tight either.

SVcummins · May 25, 2021

.0018 . Id really like to know the spec but thats kinda what the local guy who does a lot of engines Says is ok

Janicholson · May 25, 2021

I agree. Near two is perfection in my book. Oil film clearance, and broad pressure platform on that oil. Imagine .050 clearance. Not only a bad knock, but the contact patch between the journal and insert becomes a line! Calling a Cummins shop would probably be effective if you are still nervous. Jim

hunt · May 25, 2021

.002 min 0.005 max.

WellWorn · May 25, 2021

(quoted from post at 12:02:47 05/25/21) .0018 . I'd really like to know the spec ...

.0018 is about 10 times too tight, being as oil film thickness runs at about .002, depending on oil type, weight, engine temp, and several other factors. Methinks a dismal (decimal) point was misplaced. Either that, or I'm going to have to get a new set of feeler gauges, and someone with better feel to run them.

Janicholson · May 25, 2021

Well if we multiply .0018 time 10 we get .018 which a medium size ant can crawl through. Jim

rustred · May 25, 2021

well its good to me, how u figure that?

rustred · May 25, 2021

ya, or a points setting, lol.

SVcummins · May 25, 2021

We sure as hell dont want 18 thousandths of clearance on a Polished crank and new bearings insert in the spec is 4 thousandths max .

4wdtom · May 25, 2021

I don't know about that engine but .002 is a good for a lot of engines

Leon R · May 25, 2021

(quoted from post at 14:35:49 05/25/21) I don't know about that engine but .002 is a good for a lot of engines

his is from my 1994 Service manual for the 5.9 cummins.

WellWorn · May 25, 2021

(quoted from post at 15:38:58 05/25/21) We sure as hell don't want 18 thousandths of clearance on a Polished crank and new bearings insert in the spec is 4 thousandths max .

You;re right that 18 thou is too much for bearing clearance. My bad for not having my reading glasses on and conflating a 24 valve-something as "valve tappet clearance", so .015-.018 would generally be in the ball park, whereas .0018 would be far too close. Somehow I missed the "rod bearing" part of the original question. Dang cataracts...

And I'm surprised that the book lists 0.0127, or almost 13 thou as spec, which a quite small ant could crawl through. But I'm not the n-g-neer who worked that number out for a million miles of use.

used red MN · May 25, 2021

SV per Leon you skated in by 0.0001. And if you are doing this strictly by a micrometer and snap gauge I doubt you are that close. I say that simply because to be precise with those measurement tools you need experience and practice every day. Now if you had a Sunnen dial bore gauge measuring against your micrometer for me it would be a little more believable. From the stand point of what you are doing if that is a plastigauge measurement I would be way more confident in it. Just my two cents worth and nothing against you, just stating facts about tools of the trade.

SVcummins · May 25, 2021

5 tenths to 2 thousandths and 2 tenths ?

CenTex Farmall · May 25, 2021

Where was that post about running heavy oil?

used red MN · May 25, 2021

The book is in mm millimeters, I admit I missed that as
well.

SVcummins · May 25, 2021

Im just trying not to be the guy whos on here in two weeks wondering why the engine blew up . Not impressed with the service manuals lack of information at all

fdt860 · May 25, 2021

And I'm surprised that the book lists 0.0127, or almost 13 thou as spec, which a quite small ant could crawl through. But I'm not the n-g-neer who worked that number out for a million miles of use.

Millimeters!!

SVcummins · May 25, 2021

Its also in thousandths

SVcummins · May 25, 2021

Specs are given In inches and I thought I was the only one who couldnt see something when I looked right at it

gbs · May 26, 2021

if you want the scoop on on those engines look Deboss Garage

Anybody have access to a cummins

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