Technical: Engine Rebuild Question
irontodd
11-06-2004, 05:17 PM
I have been unfortunate enough to have to rebuild my 2.5L TJ Wrangler engine. I have the Haynes manual, but I am pretty sure there are some typos in the engine overhaul specs. some of the numbers just SEEM awfully small to me... In chapter 2, part C: General engine overhaul procedures, I'm looking to find some other specs (as a second opinion kinda thing, maybe Chiltons, or JEEP FACTORY SERVICE MANUAL) on Piston Ring End Gap, Piston to bore clearance, and Piston ring side clearance... the numbers in Haynes are in the .0010 range, but the smallest feeler gauge I have is .0025, and that's thnner than paper. I'm just wondering if they accidentally put an extra zero in there... maybe the numbers are supposed to be in the .010 range instead of .0010? I'm looking for exact spec's.
Thanks
Thanks
fredjacksonsan
11-10-2004, 10:23 AM
My brother has built alot of engines, I'm waiting on a response from him on this one.
goinbig
11-10-2004, 08:39 PM
My hayne's manual is saying the same as yours, but I'll look in some other places to see if I can find any more info for ya
JDPascal
11-11-2004, 12:07 AM
These clearances are from a 93 cherokee/wrangler factory manual. The 2000 should not have changed in this area but you can decide for your self if you want to use them for your engine.
rings 1&2-
end gap - .010" - .020"
side clearance - .0017" - .0032"
ring 3
end gap - .015" - .055"
side clearance .001" - .010"
Rule of thumb with ring end gaps is .003" - .004" gap per inch of bore diameter. These numbers match up with the specs for an 84 listed in chiltons too.
piston to bore clearance .0013" - .0021"
It also says to replace the pistons if the bore clearance is more than .004"
The piston-bore clearance sounds about right and is just a little looser than the spec for the same engine in 84 as listed a my chiltons (.0009"-.0017").
hope this helps.
JD
rings 1&2-
end gap - .010" - .020"
side clearance - .0017" - .0032"
ring 3
end gap - .015" - .055"
side clearance .001" - .010"
Rule of thumb with ring end gaps is .003" - .004" gap per inch of bore diameter. These numbers match up with the specs for an 84 listed in chiltons too.
piston to bore clearance .0013" - .0021"
It also says to replace the pistons if the bore clearance is more than .004"
The piston-bore clearance sounds about right and is just a little looser than the spec for the same engine in 84 as listed a my chiltons (.0009"-.0017").
hope this helps.
JD
fredjacksonsan
11-11-2004, 02:02 AM
My bro's answer goes with all the above:
"End gap is usuall a ratio using the bore size. The 440 was about .012", but since I had Hyperutectic pistons (high silicon content) the top ring had to be about .027" because the piston tops for those types
of pistons run much hotter.
Piston to bore also is variable but is less that end gap, I'd have to look it up. Ring side clearance is the smallest of the measurements if I remember right. "
I'd go with JDPascal on this one, factory manual is likely to be correct.
"End gap is usuall a ratio using the bore size. The 440 was about .012", but since I had Hyperutectic pistons (high silicon content) the top ring had to be about .027" because the piston tops for those types
of pistons run much hotter.
Piston to bore also is variable but is less that end gap, I'd have to look it up. Ring side clearance is the smallest of the measurements if I remember right. "
I'd go with JDPascal on this one, factory manual is likely to be correct.
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