76 Chopokee

I've purchased new lifters after realizing I didn't mark them well enough and my markings have disappeared. I understand they should go back on the lobe they were on prior. So, new Sealed Power HT-2011s are going in instead. I'll be reusing pushrods, they're all straight and I got them very clean. My replacement motor is a '97, my Jeep is a '94.

My question at this point is, do I need to worry about setting the motor at TDC and looking at valve lash when I bolt the cylinder head back on? I don't recall worrying about it when I did the 4.0 head swap on my '88 Eagle, and it started up and ran fine.

Also, which parts in particular should get some assembly lube? Obviously lifters and cam, do I need to worry about the crank or anything else?

Thanks guys, couldn't do this without the forum!

djb383

I believe the lash is set when the rocker bridges r torqued to 21 ft/lbs. Was the crank removed?.....the entire rotating assembly should have assembly lube and the rotating assembly should be rotated as little as possible prior to initial start-up.

cruiser54

You're good if you have assembly lube on new parts.

For initial start-up, disconnect the CPS and crank the motor over till you see good oil pressure on the gauge.

Then plug the CPS back and start it up and do the cam break-in procedure.

s346k

so you're rebuilding a flat tappet cam motor and planned on reusing the old lifters and cam?

Firestorm500

Sounds like he's using the old cam and new lifters(!).

cruiser54

Yep.

And only because the lifters he took out and marked by position on the cam lost their markings.

Fred/N0AZZ

Must be his first rebuild and won't take him long to find out why he should have replaced both with new. The only cam and lifters that I reuse are roller setups and they are checked very close to see what motor I want them on.

Firestorm500

Well if he's using the old cam, maybe he should have just pulled the pan and put rings, crank and rod bearings in it.

That was called an "overhaul" back in the day.

cruiser54

He'll be fine.

steelybill

Cam break-in is very important with flat tappets.....DON'T let it idle !! Take it on up to 1800 to 2200 for at least 20 minutes.

Having a cam & lifters fail will spread metal through the entire engine, and the only way to get it cleaned out is a complete diss-assembly & cleaning.

( don't ask how I know this )

freegdr

What actually was rebuilt ?

76 Chopokee

Woah boys, lots of confusion going on here.

I'm 'refreshing' a '97 4.0 with 150k on it. The crank was replaced by the previous owner and the engine was run for a short while with the new crank, bearings, and seals. I would hope the previous rebuild included rings, but I'm not going to mess with it since it's assembled. It has good compression.

Yes, I'm using new lifters with an old cam. No, that's not going to cause problems. I'd be in much worse shape if I reused the old lifters but put them on different lobes. Lifters will get assembly lube and I'll be gentle on the first startup.

The cam isn't gonna be shot at 150k, and I see no need to replace it with new. Let go of your engine superstitions. Cruiser is right, I will be fine. Was just curious about lash, which was answered in the first reply. Sounds like I won't need to follow any special procedures other than initial cam break-in to mate the lifters.

freegdr

This would be my only area of concern ....I would hope the previous rebuild included rings

76 Chopokee

I go back and forth. On one hand it's easy enough to do the rings, but on the other hand I'd rather not mess with the rods and bearings. The thing that worries me is that when I pulled the head, it seemed like the head hadn't been off before. I suppose it's possible to replace the crank without pulling the head but I'm not sure why that would be done. At any rate, the head has been cleaned, machined flat, three angle valve grind, and new valve seats. Springs were within spec.

Talk me out of leaving the rings alone if you think they're really that risky to use.

freegdr

It just while motors out there alot easier to replace than when its in, cam bearings also fall into this category . New top end old bottom end just a risk I would not bet on with my luck...lol...