Valve adjustment in rebuild
Thread Starter
Senior Member
Joined: Jan 2017
Posts: 541
Likes: 70
From: Southern MD
Model: Cherokee
Dave, thanks for your reply.
This is a complete rebuild, with new cam and lifters. It was a stage 1 cam from Clegg.
Specs:
Duration 263 Intake | 267 Exhaust
Duration @ 0.050 Valve Lift 209 Intake | 213 Exhaust
Valve Lift 0.443 Intake | 0.443 Exhaust
Lobe Seperation Angle 114 Degrees
The preload with the original pushrods is consistent at ~.065 across the board.
I will measure my current rods today, and that will lead to the next question.
Is a 5/16 dia push rod with "ball ends" all the same??
Inother words here is a 9.62" 5/16 pushrod,, for a Ford motor,, If 9.62 is the length I end up needing would these work??
Or are the ball ends manufacture specific.
I an hesitant using shims,, it seems like the Kludge way of doing it ??
This is a complete rebuild, with new cam and lifters. It was a stage 1 cam from Clegg.
Specs:
Duration 263 Intake | 267 Exhaust
Duration @ 0.050 Valve Lift 209 Intake | 213 Exhaust
Valve Lift 0.443 Intake | 0.443 Exhaust
Lobe Seperation Angle 114 Degrees
The preload with the original pushrods is consistent at ~.065 across the board.
I will measure my current rods today, and that will lead to the next question.
Is a 5/16 dia push rod with "ball ends" all the same??
Inother words here is a 9.62" 5/16 pushrod,, for a Ford motor,, If 9.62 is the length I end up needing would these work??
Or are the ball ends manufacture specific.
I an hesitant using shims,, it seems like the Kludge way of doing it ??
https://www.pushrods.net/one-piece-pushrods
Since this is a complete rebuild you already got a new cam and lifters?
I would consider getting a caliper, measure your current rods and work from that.
Since this is a complete rebuild you already got a new cam and lifters?
I would consider getting a caliper, measure your current rods and work from that.
Thread Starter
Senior Member
Joined: Jan 2017
Posts: 541
Likes: 70
From: Southern MD
Model: Cherokee
Thanks,
My .065 preload is pretty consistent, so equal shims would not be a problem.
My .065 preload is pretty consistent, so equal shims would not be a problem.
To answer your question yes, you should. Too much preload runs the risk of poor pumping from the plunger as it doesn't travel enough in the bore, or hammering the plunger causing destructive failure. Not enough will cause poor engine vacuum. For too much preload, you can adjust it out with the shorter pushrods as you say, but an easier way might be to order the adjustment shim washers from Crane. That's what I did. That will raise your rockers and accomplish the same thing.
Within spec is within spec, its the factory way of balancing lifter operation with vacuum.
http://www.summitracing.com/parts/cr...1/applications
Remember the trick is to shim both I and E equally . It says that in the instructions that come with the shims. Therefore you still might need a pushrod down the road if you can't.
Even with the shims I wasn't able to completely get just the exhaust on #6 to completely come in so I need a pushrod. Its operating at the margin like yours, or slightly out. And Darned if when it gets below about 35 outside, that baby ticks for exactly one second, which you can barely hear over the piston slap that has been there for 65000 miles (215,000)..which fades to silence in a minute or two or three. One of these days Ill likely be getting a pushrod.
I still love my 97 zj. The hatch window I can and do stuff so much crud in the thing and it always gets my job done. Its been my main work vehicle for like 10 years and one way or another it's never 100 percent but always, always gets the job done.
Within spec is within spec, its the factory way of balancing lifter operation with vacuum.
http://www.summitracing.com/parts/cr...1/applications
Remember the trick is to shim both I and E equally . It says that in the instructions that come with the shims. Therefore you still might need a pushrod down the road if you can't.
Even with the shims I wasn't able to completely get just the exhaust on #6 to completely come in so I need a pushrod. Its operating at the margin like yours, or slightly out. And Darned if when it gets below about 35 outside, that baby ticks for exactly one second, which you can barely hear over the piston slap that has been there for 65000 miles (215,000)..which fades to silence in a minute or two or three. One of these days Ill likely be getting a pushrod.
I still love my 97 zj. The hatch window I can and do stuff so much crud in the thing and it always gets my job done. Its been my main work vehicle for like 10 years and one way or another it's never 100 percent but always, always gets the job done.
Thread Starter
Senior Member
Joined: Jan 2017
Posts: 541
Likes: 70
From: Southern MD
Model: Cherokee
I am thinking the Melling MPR-437 will work, it is 9.639" x 5/16,,, but are the ends correct? they show 2 types of ball ends
https://www.melling.com/wp-content/u...tion-chart.pdf
https://www.melling.com/wp-content/u...tion-chart.pdf
CF Veteran
Joined: Jan 2017
Posts: 3,413
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From: Connecticut
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
I am thinking the Melling MPR-437 will work, it is 9.639" x 5/16,,, but are the ends correct? they show 2 types of ball ends
https://www.melling.com/wp-content/u...tion-chart.pdf
https://www.melling.com/wp-content/u...tion-chart.pdf
Thread Starter
Senior Member
Joined: Jan 2017
Posts: 541
Likes: 70
From: Southern MD
Model: Cherokee
Picked up 2) MPR-437s at local auto parts store.
They ended up being the exact same size as my original ~9.65 - 9.66,, NOT 9.639
I ordered 2) MRP-333 (9.622") they should be here Wednesday
They ended up being the exact same size as my original ~9.65 - 9.66,, NOT 9.639
I ordered 2) MRP-333 (9.622") they should be here Wednesday
CF Veteran
Joined: Jan 2017
Posts: 3,413
Likes: 400
From: Connecticut
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Thread Starter
Senior Member
Joined: Jan 2017
Posts: 541
Likes: 70
From: Southern MD
Model: Cherokee
Thread Starter
Senior Member
Joined: Jan 2017
Posts: 541
Likes: 70
From: Southern MD
Model: Cherokee
Installed Melling MPR-333 pushrods (9.622")
All lifter preload fell between .049 - .056 on the diagram,,
Ran the oil pump with a drill and all pushrods flowed oil,, so I am saying it is good.
Now to finish this up and get it in the XJ!!
All lifter preload fell between .049 - .056 on the diagram,,
Ran the oil pump with a drill and all pushrods flowed oil,, so I am saying it is good.
Now to finish this up and get it in the XJ!!
CF Veteran
Joined: Nov 2015
Posts: 2,856
Likes: 201
From: syracuse ny
Year: 1997
Model: Grand Cherokee (ZJ)
Engine: 4.0, new lifters valve job with new springs and exhaust valves, preload set with shims
Nice job. I missed this was an engine out job. I'm sure you know this but contrary to what many have said do not operate above an idle when you first start it.... until they all oil up.
Last edited by 97grand4.0; Feb 12, 2021 at 06:16 PM.
Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 740
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
On a new engine start, I'll kill the ignition and crank it until oil pressure comes up before I'll light it off.
CF Veteran
Joined: Nov 2015
Posts: 2,856
Likes: 201
From: syracuse ny
Year: 1997
Model: Grand Cherokee (ZJ)
Engine: 4.0, new lifters valve job with new springs and exhaust valves, preload set with shims
sup Mr Dave. You could be cranking that starter and battery for a while before the rockers all oil up. Book says start and operate at idle. Even then it does take a minute.