Author Topic: 95 2.5L Top End Rebuild: Push Rod question ???  (Read 3808 times)

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JimmyFW1

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95 2.5L Top End Rebuild: Push Rod question ???
« on: September 21, 2011, 11:29:05 AM »
OK, ya'll may see from my other post that I'm having to rebuild the top end of my 4-banger.
I read on a post over on jeepsunlimited.com that someone use a touch longer push rod to create a stroker effect.
Is this possible by just getting a touch longer pushrod?
I know I don't know much about engine internals, but this sounds iffy to me...

Any thoughts???

Torch_Ind

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #1 on: September 21, 2011, 04:46:47 PM »
if you don't know how to check that I wouldn't play with stuff like that. you could end up with valves  that don't close if you go to long

Offline grumpygy

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #2 on: September 21, 2011, 05:30:07 PM »
if you don't know how to check that I wouldn't play with stuff like that. you could end up with valves  that don't close if you go to long

Or Valves that contact the Piston.
94 YJ, Cool Air intake, 19lb Inj, 4.0 Throttlebody with spacer,  31/10.50/15's

Offline sharpxmen

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #3 on: September 21, 2011, 08:03:21 PM »
OK, ya'll may see from my other post that I'm having to rebuild the top end of my 4-banger.
I read on a post over on jeepsunlimited.com that someone use a touch longer push rod to create a stroker effect.
Is this possible by just getting a touch longer pushrod?
I know I don't know much about engine internals, but this sounds iffy to me...

Any thoughts???

for valves you use the correct length pushrod to achieve the correct hydaulic lifter preload, too long and your valves will stay open (and your engine will run like crap and that is if it will start) , too short and they'll be noisy or worst case scenario they will come out of the rockers (although that is extreme). using longer pushrods will not give you more valve lift, that's not possible and as far as displacement (more displacement in the case of a stroker) the valvetrain has nothing to do with it, get a different cam if you want more lift or more overlap, different duration, different open/close angles, etc - regardless of the pushrod length your valves will open/close at the same rotational angle points and will generate the same amount of lift (given that there is some preload and the lifters are not bottoming out).

'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

JimmyFW1

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #4 on: September 22, 2011, 09:51:03 AM »
for valves you use the correct length pushrod to achieve the correct hydaulic lifter preload, too long and your valves will stay open (and your engine will run like crap and that is if it will start) , too short and they'll be noisy or worst case scenario they will come out of the rockers (although that is extreme). using longer pushrods will not give you more valve lift, that's not possible and as far as displacement (more displacement in the case of a stroker) the valvetrain has nothing to do with it, get a different cam if you want more lift or more overlap, different duration, different open/close angles, etc - regardless of the pushrod length your valves will open/close at the same rotational angle points and will generate the same amount of lift (given that there is some preload and the lifters are not bottoming out).

That's exactly the kind of response & information I was expecting.  THANKS

Offline sharpxmen

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #5 on: September 22, 2011, 10:13:55 AM »
That's exactly the kind of response & information I was expecting.  THANKS

remember to figure out why that valve is open on your old head, make sure it's not bent and if it is find out why. And also replace the lifters and pushrods (not optional at this point for you given the history) to avoid any issues (they are dirt cheap so not an issue there).
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

JimmyFW1

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #6 on: September 22, 2011, 02:01:07 PM »
remember to figure out why that valve is open on your old head, make sure it's not bent and if it is find out why. And also replace the lifters and pushrods (not optional at this point for you given the history) to avoid any issues (they are dirt cheap so not an issue there).

I will be getting back to work on it this weekend, weather permitting (no garage).
I had planned on replacing the rods, rockers, lifters, pivots & retainers.  Since I'm putting the work into putting a new head on it, I might as well have all newer hardware.
And my brother-in-law (who has been a Chrysler mechanic for about 9 years now) was helping me break it down last weekend.  He said visually the bottom end looked good, but as we all know (him included) we can't tell 100% for sure unless it's broken all the way down.  And the valve guide appeared to the be problem.  His thought was that I just bought myself some time by having the #3 done awhile back, when I should have had the whole valve train redone.
Que sera sera...

Will let ya'll know when i get it back together...


The donor motor owner that sold me the reman'd head also had a 4.0 TB on the motor & the rest of the motor too.  Wanna take the intake to have it bored to match the 4.0 TB bore, and have it sandblasted & polished out internally too...
I figure that'll help it inhale a little better, and along with the new headers I was given it'll exhale better too...
 :koolaid:

Torch_Ind

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #7 on: September 22, 2011, 04:27:12 PM »
  And the valve guide appeared to the be problem.  His thought was that I just bought myself some time by having the #3 done awhile back, when I should have had the whole valve train redone.
Que sera sera...

The donor motor owner that sold me the reman'd head also had a 4.0 TB on the motor & the rest of the motor too.  Wanna take the intake to have it bored to match the 4.0 TB bore, and have it sandblasted & polished out internally too...
I figure that'll help it inhale a little better, and along with the new headers I was given it'll exhale better too...
 :koolaid:

I though it sounded funny you only replaced 1 valve.

and you could always get a 62-64mm tb and port match everything to it!!  I would recommend getting new cam or performance cam if possible. and having the crank checked/turned at the same time!!

!!!do it right the first time!!!

Offline grumpygy

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #8 on: September 22, 2011, 05:26:47 PM »
I though it sounded funny you only replaced 1 valve.

and you could always get a 62-64mm tb and port match everything to it!!  I would recommend getting new cam or performance cam if possible. and having the crank checked/turned at the same time!!

!!!do it right the first time!!!

Waqnna point me to a cam besides the Hesco one.
94 YJ, Cool Air intake, 19lb Inj, 4.0 Throttlebody with spacer,  31/10.50/15's

Torch_Ind

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #9 on: September 22, 2011, 07:02:40 PM »
Waqnna point me to a cam besides the Hesco one.

honestly I didn't think they were available  unless you found a used one was my last understanding

the hesco one is new info to me

Offline grumpygy

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #10 on: September 22, 2011, 07:04:07 PM »
Found Dodge /Jeep Performance number of.  P4529658

Anybody know where to get one and was it worth it.
94 YJ, Cool Air intake, 19lb Inj, 4.0 Throttlebody with spacer,  31/10.50/15's

Offline Jeffy

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #11 on: September 22, 2011, 08:48:52 PM »
Found Dodge /Jeep Performance number of.  P4529658

Anybody know where to get one and was it worth it.
NOS only.  Just about every Dealer liquidated their stock if they had any years ago.  There are actually 6 Mopar Performance Purple cams.  Check the FAQ and the profile should be there.
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Offline sharpxmen

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #12 on: September 22, 2011, 08:52:14 PM »
Waqnna point me to a cam besides the Hesco one.

Crane and Comp cams or get a regrind

The donor motor owner that sold me the reman'd head also had a 4.0 TB on the motor & the rest of the motor too.  Wanna take the intake to have it bored to match the 4.0 TB bore, and have it sandblasted & polished out internally too...
I figure that'll help it inhale a little better, and along with the new headers I was given it'll exhale better too...
 :koolaid:

there no need to bore the intake with a 4.0L t/b, it's already the same as the intake manifold maybe take of 1mm around with a semi-round file if you want it to be the exact same diameter (they are very close though).
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

Torch_Ind

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #13 on: September 25, 2011, 04:10:12 PM »
is the hesco one no good?

Offline grumpygy

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Re: 95 2.5L Top End Rebuild: Push Rod question ???
« Reply #14 on: September 25, 2011, 04:17:13 PM »
is the hesco one no good?

Not sure but with a price of
289.00 and you need a Valve spring kit for
 89.00
378.00 seems kind of high for a cam

and you still need to get new lifters.
94 YJ, Cool Air intake, 19lb Inj, 4.0 Throttlebody with spacer,  31/10.50/15's