Reinstall rocker arm questions on 258???

[Mike KC]

I am a new jeep owner (a week). Wife thought we needed a new toy it is 1984 CJ7 with a AMC 258 i6 / 4.2l 4 speed. My intention is to finish the restore the previous owner started before he ran out of money and became unemployed.

The engine smoked no matter what engine temp - cold, warm, hot. I rebuilt the Carter carburetor and got it pulling about 22 inches of vacuum. I put new plugs in and ran it for about 10 minutes, 1,3,4 plugs looked normal. 2,5, really 6 looked like it had black carbon baked on it. Not drippy oil but hard and dry black. Cylinder compression is:

1 - 120
2 - 135
3 - 128
4 - 130
5 - 125
6 - 140

A new jeep friend recommended replacing the valve seals thinking that was where the oil was coming from as well as account for the higher compression (carbon buildup) in the #6 cylinder. When I started putting the rocker arms back on last night and began reading the assembly process in the FSM and Chilton manual, it doesn't say anything about valve lashing, only 19 ft lbs of torque. How do I set the rocker arms back like they should go?

Thanks, sorry its so long of an explanation.

 

[Buuushman]

On motors with hydraulic lifters setting valve lash is not necessary, they are zero clearance setups. Just be sure everything goes back where it came from and torque to spec.

 

[Mike KC]

Okay, do I need to worry about where the cam is at? If any valves are opened or closed?

 

[Buuushman]

no- the lifters simply collapse as you tighten every thing up, and when you start it you will get valvetrain rattle untill the lifters get pumped up. Some guys soak the lifters in oil first to partially fill them before firing it up but if you give everything a liberal coating of oil or break in lube you should be fine.

 

[IOPort51]

Just so you are aware, AMC 258 i6 / 4.2l /4.0 AMC l6’s like to crack heads between valves, it’s kind of what they do. This will foul specific plugs and burn a little oil. I do hope your valve seals do the trick and this becomes information you never need.

 

[blkstx87]

Is it possible to pull those Hyd lifters out without removing the head ? Will they come out of the pushrod holes?

 

[IOPort51]

I doubt it, if they would fit through the head it would be difficult to get a hold on them and they may need more than a gentle tug to get them out.
It would more than likely be the hard way, even if it required a head gasket.

Is it possible to pull those Hyd lifters out without removing the head ? Will they come out of the pushrod holes?

 

[Mike KC]

Once that didn't fix the problem I pulled the motor and found that the #6 cylinder had a broke oil ring. Head and block are in the shop right now getting cleaned and bored.

New engine will be ready before I am.

 

[gert]

well at least you will have a new strong motor

 

[Cheepjeep85]

eh you'll be glad you done it that motor should last another 200,000 miles. plus you'll have the piece of mind knowing you got a good motor.

 

[Cheepjeep85]

you can't adjust the valves on a AMC 258 i6 / 4.2l like a say a small block chevy you just torque the rocker arms down to 19ftlbs and go with it.