Please help settle difference of opinion

I dunno, my John Deere I-6 has gaps. :^)

Bill,

I haven't done the 4.0L head change on my 4.2L engine yet. As far as I can remember from reading the FSM, I should not have to gap the rocker arm on my 4.2L head when I put it back on. I only need to make sure it's correctly placed and torque it down.

Does the 4.2L head have hydraulic lifters as well?

Thanks,

Bill

Neither head has any lifters at all!

Now the blocks.... yes both are hydraulic.

Mike

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

William Oliveri wrote:

The point of the hydraulic lifter is to close that gap up. If there is a gap, then the lifter(s) will be noisy. I suppose on a static test, there coulcl be a small gap, but it would be measured in the 1/1000s of an inch. I think you would be looking at a number of about 0.0050 or less.

I have the factory shop manual for this motor, and I could look up the exact spec for you if you want.

Can I send you my phone number at the email address you listed, or can you send me your phone # to jstrickland at EZ2 dot net? I'll check my manual and call you back with the spec.

I gapped hydraulic lifters once with my Dad. It was about 35 years ago, so it is a fuzzy memory at best. I think we warmed the motor to operating temp, then pulled the valve covers at idle and adjusted the valves so they were all quiet, then backed each one off until it made noise and adjusted it down until it was quite, then added a half-turn. It was kind of difficult because the stuff to adjust is moving, but other than working on moving parts, it was not really that difficult.

I have the FSM at home and I remember reading it when I was first working on the rocker arm bridge when I changed my valve cover to an Aluminum one. I don't ever reading anything about having to gap when the rocker arm was replaced.

Bill

I am VERY fuzzy on this, but if there are adjusters on the rocker arms, then there is a need to adjust them at least once. I thought the goal was to adjust them until they made no noise, I don't recall a gap spec. If they are adjusted too tight, then the valves might not close fully, but if they are adjusted too loose, the valves will make noise. It is better to have some clatter than to have valves that do not close tightly, but even that rule of thumb can be abused.

The only thing I can remember is that it needed to be torqued down. I'll check it when I get home.

bill

It calls for 0 lash.

You just torque it. If any are loose, the lifters need changing.

Mike

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

William Oliveri wrote:

I see the key word being slowly. Why did you say it like that? Not being careful can cause the bolts to be over torqued and break off or strip out?

Thanks,

bill

Great info. Thanks.