Brent

Hello,

I am stroking my 91 cherokee 4.0 with a 258 crank and 258 rods. My
crankshaft end play is at 0.0055 inches. The range is 0.0015-0.0065
inches . The ideal range is ~ 0.002-0.0025 inches. My machinist tells
me that the end play is perfect and less could cause friction
problems, i.e burn out. To me, if it is engineered for .002-.0025 that
should be the optimal range. I'm at the high end for wear according to
the manual, and I see this giving me less engine life.

Also, my side cleance is 0.022 in. and .019 in. for two of the
connecting rods. The range is 0.01-0.019 inches. My machinsts told me
the .022 will not be a problem.

I'm concerned with my machine shops responce. Yes it will run fine,
but how about 50K mi from now? Is my machinist BS'ing me becaused they
screwed up or are thses tolerances acceptable for a rebuild?

Thanks

HomeBrewer

I'm no machanist, but I would not be happy with these numbers. Especially of
you're paying him good money for this service. Maybe someone here can answer
more thorouhghly, if not get a second opinion from another machinist in your
area.
--
_____________________
HomeBrewer
85CJ7 (in Progress)
http://85cj7.blogspot.com/
99XJ Sport
Remove the xxx to reply!

HomeBrewer

I'm no machanist, but I would not be happy with these numbers. Especially of
you're paying him good money for this service. Maybe someone here can answer
more thorouhghly, if not get a second opinion from another machinist in your
area.
--
_____________________
HomeBrewer
85CJ7 (in Progress)
http://85cj7.blogspot.com/
99XJ Sport
Remove the xxx to reply!

HomeBrewer

I'm no machanist, but I would not be happy with these numbers. Especially of
you're paying him good money for this service. Maybe someone here can answer
more thorouhghly, if not get a second opinion from another machinist in your
area.
--
_____________________
HomeBrewer
85CJ7 (in Progress)
http://85cj7.blogspot.com/
99XJ Sport
Remove the xxx to reply!

HomeBrewer

I'm no machanist, but I would not be happy with these numbers. Especially of
you're paying him good money for this service. Maybe someone here can answer
more thorouhghly, if not get a second opinion from another machinist in your
area.
--
_____________________
HomeBrewer
85CJ7 (in Progress)
http://85cj7.blogspot.com/
99XJ Sport
Remove the xxx to reply!

c

"Brent" <bjn2000@yahoo.com> wrote in message
news:d9f2fc77.0408030958.430d48c0@posting.google.c om...
> Hello,
>
> I am stroking my 91 cherokee 4.0 with a 258 crank and 258 rods. My
> crankshaft end play is at 0.0055 inches. The range is 0.0015-0.0065
> inches . The ideal range is ~ 0.002-0.0025 inches. My machinist tells
> me that the end play is perfect and less could cause friction
> problems, i.e burn out. To me, if it is engineered for .002-.0025 that
> should be the optimal range. I'm at the high end for wear according to
> the manual, and I see this giving me less engine life.
>
> Also, my side cleance is 0.022 in. and .019 in. for two of the
> connecting rods. The range is 0.01-0.019 inches. My machinsts told me
> the .022 will not be a problem.
>
> I'm concerned with my machine shops responce. Yes it will run fine,
> but how about 50K mi from now? Is my machinist BS'ing me becaused they
> screwed up or are thses tolerances acceptable for a rebuild?
>
> Thanks

Crankshaft endplay is not something that is usually controlled by the
machinist. The main thrust bearing and the thrust face on the crank will
determine that for the most part. There really is not a way to tighten the
endplay up. The crankshaft thrust surfaces wear and a new bearing is
manufactured to match up with a new crank. Personally I wouldn't worry about
it. A little more clearance there will allow a bit more oil to pass over the
thrust surface. In all honesty, most engines have a larger endplay dimension
than that. About the only way to tighten the clearances are a different
crankshaft. Again, the rod side clearances are pretty much determined by the
width of the rods and the width of the rod journals. The only way to change
it is to replace the rods or crank. One other thing to consider is that
since this is a 258 crank, what are the end play and side clearance
dimensions for a 258? You might find that they are right in spec. When you
mix and match parts these things need to be considered. It is good that you
are concerned about these clearances of course. In all honesty most
non-stock engines that are going to see more severe duty than normal usually
have these clearances opened up a bit.

Chris

c

"Brent" <bjn2000@yahoo.com> wrote in message
news:d9f2fc77.0408030958.430d48c0@posting.google.c om...
> Hello,
>
> I am stroking my 91 cherokee 4.0 with a 258 crank and 258 rods. My
> crankshaft end play is at 0.0055 inches. The range is 0.0015-0.0065
> inches . The ideal range is ~ 0.002-0.0025 inches. My machinist tells
> me that the end play is perfect and less could cause friction
> problems, i.e burn out. To me, if it is engineered for .002-.0025 that
> should be the optimal range. I'm at the high end for wear according to
> the manual, and I see this giving me less engine life.
>
> Also, my side cleance is 0.022 in. and .019 in. for two of the
> connecting rods. The range is 0.01-0.019 inches. My machinsts told me
> the .022 will not be a problem.
>
> I'm concerned with my machine shops responce. Yes it will run fine,
> but how about 50K mi from now? Is my machinist BS'ing me becaused they
> screwed up or are thses tolerances acceptable for a rebuild?
>
> Thanks

Crankshaft endplay is not something that is usually controlled by the
machinist. The main thrust bearing and the thrust face on the crank will
determine that for the most part. There really is not a way to tighten the
endplay up. The crankshaft thrust surfaces wear and a new bearing is
manufactured to match up with a new crank. Personally I wouldn't worry about
it. A little more clearance there will allow a bit more oil to pass over the
thrust surface. In all honesty, most engines have a larger endplay dimension
than that. About the only way to tighten the clearances are a different
crankshaft. Again, the rod side clearances are pretty much determined by the
width of the rods and the width of the rod journals. The only way to change
it is to replace the rods or crank. One other thing to consider is that
since this is a 258 crank, what are the end play and side clearance
dimensions for a 258? You might find that they are right in spec. When you
mix and match parts these things need to be considered. It is good that you
are concerned about these clearances of course. In all honesty most
non-stock engines that are going to see more severe duty than normal usually
have these clearances opened up a bit.

Chris

c

"Brent" <bjn2000@yahoo.com> wrote in message
news:d9f2fc77.0408030958.430d48c0@posting.google.c om...
> Hello,
>
> I am stroking my 91 cherokee 4.0 with a 258 crank and 258 rods. My
> crankshaft end play is at 0.0055 inches. The range is 0.0015-0.0065
> inches . The ideal range is ~ 0.002-0.0025 inches. My machinist tells
> me that the end play is perfect and less could cause friction
> problems, i.e burn out. To me, if it is engineered for .002-.0025 that
> should be the optimal range. I'm at the high end for wear according to
> the manual, and I see this giving me less engine life.
>
> Also, my side cleance is 0.022 in. and .019 in. for two of the
> connecting rods. The range is 0.01-0.019 inches. My machinsts told me
> the .022 will not be a problem.
>
> I'm concerned with my machine shops responce. Yes it will run fine,
> but how about 50K mi from now? Is my machinist BS'ing me becaused they
> screwed up or are thses tolerances acceptable for a rebuild?
>
> Thanks

Crankshaft endplay is not something that is usually controlled by the
machinist. The main thrust bearing and the thrust face on the crank will
determine that for the most part. There really is not a way to tighten the
endplay up. The crankshaft thrust surfaces wear and a new bearing is
manufactured to match up with a new crank. Personally I wouldn't worry about
it. A little more clearance there will allow a bit more oil to pass over the
thrust surface. In all honesty, most engines have a larger endplay dimension
than that. About the only way to tighten the clearances are a different
crankshaft. Again, the rod side clearances are pretty much determined by the
width of the rods and the width of the rod journals. The only way to change
it is to replace the rods or crank. One other thing to consider is that
since this is a 258 crank, what are the end play and side clearance
dimensions for a 258? You might find that they are right in spec. When you
mix and match parts these things need to be considered. It is good that you
are concerned about these clearances of course. In all honesty most
non-stock engines that are going to see more severe duty than normal usually
have these clearances opened up a bit.

Chris

c

"Brent" <bjn2000@yahoo.com> wrote in message
news:d9f2fc77.0408030958.430d48c0@posting.google.c om...
> Hello,
>
> I am stroking my 91 cherokee 4.0 with a 258 crank and 258 rods. My
> crankshaft end play is at 0.0055 inches. The range is 0.0015-0.0065
> inches . The ideal range is ~ 0.002-0.0025 inches. My machinist tells
> me that the end play is perfect and less could cause friction
> problems, i.e burn out. To me, if it is engineered for .002-.0025 that
> should be the optimal range. I'm at the high end for wear according to
> the manual, and I see this giving me less engine life.
>
> Also, my side cleance is 0.022 in. and .019 in. for two of the
> connecting rods. The range is 0.01-0.019 inches. My machinsts told me
> the .022 will not be a problem.
>
> I'm concerned with my machine shops responce. Yes it will run fine,
> but how about 50K mi from now? Is my machinist BS'ing me becaused they
> screwed up or are thses tolerances acceptable for a rebuild?
>
> Thanks

Crankshaft endplay is not something that is usually controlled by the
machinist. The main thrust bearing and the thrust face on the crank will
determine that for the most part. There really is not a way to tighten the
endplay up. The crankshaft thrust surfaces wear and a new bearing is
manufactured to match up with a new crank. Personally I wouldn't worry about
it. A little more clearance there will allow a bit more oil to pass over the
thrust surface. In all honesty, most engines have a larger endplay dimension
than that. About the only way to tighten the clearances are a different
crankshaft. Again, the rod side clearances are pretty much determined by the
width of the rods and the width of the rod journals. The only way to change
it is to replace the rods or crank. One other thing to consider is that
since this is a 258 crank, what are the end play and side clearance
dimensions for a 258? You might find that they are right in spec. When you
mix and match parts these things need to be considered. It is good that you
are concerned about these clearances of course. In all honesty most
non-stock engines that are going to see more severe duty than normal usually
have these clearances opened up a bit.

Chris

Mike Romain

I wouldn't like those numbers and I would have the journals plastigauged
before installing it. If the machine shop is that sloppy on end play,
how good are they with bearing clearances?

When I hear crap like that coming from a so called professional shop, I
tend to find a new shop sooner than later.

I am going to refresh a 258 I have in my garage maybe with my 4.0 block
and I certainly would 'not' go to all that work and expense to put in
parts that are already out of or at the limit of their tolerances.

Not a hope.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Brent wrote:
>
> Hello,
>
> I am stroking my 91 cherokee 4.0 with a 258 crank and 258 rods. My
> crankshaft end play is at 0.0055 inches. The range is 0.0015-0.0065
> inches . The ideal range is ~ 0.002-0.0025 inches. My machinist tells
> me that the end play is perfect and less could cause friction
> problems, i.e burn out. To me, if it is engineered for .002-.0025 that
> should be the optimal range. I'm at the high end for wear according to
> the manual, and I see this giving me less engine life.
>
> Also, my side cleance is 0.022 in. and .019 in. for two of the
> connecting rods. The range is 0.01-0.019 inches. My machinsts told me
> the .022 will not be a problem.
>
> I'm concerned with my machine shops responce. Yes it will run fine,
> but how about 50K mi from now? Is my machinist BS'ing me becaused they
> screwed up or are thses tolerances acceptable for a rebuild?
>
> Thanks