If it was a lifter detonation it may just require new lifters and a couple push rods.

I agree with tbear check valve travel and do a leak down test to see if the valves are bent. if you fail either of those tests the head must come off.

 

I have a 4 post lift. does front suspension need to be drooping to get the oil pan off?

fingers crossed, hoping for just a failed lifter and pushrod.

 

I don't recall if it "has" to be drooping, but it sure helps with room as the pan must clear the oil pump, etc too. As I recall, the track bar needs to be lowered at the frame end for sure. Front shocks will limit axle drop. Even if just a failed lifter, a look in the pan will be good, and so easy on a 4 post lift.

I did it to replace rod & main bearings and oil pump, in my yard, it was raining off and on. My frame was blocked up with big tall ramps made of 2x12 saw mill oak boards, sides through bolted to interior webs, with top and bottoms they ended up being overly heavy and 16" tall, they are like boxes with a ramped side. Wide flat bottoms, could have used them under a D-8. I built them before I had a paved driveway.

 

You will have to losen the front enigine plate. Some have pried it out and then resealed it with "The right stuff" by prestone I think. I've also heard of cutting the lip off.

 

assuming we pass leakdown test, can I just replace the lifters on #1 and the pushrods, or should I replace all of them while I'm there? I'm guessing I'll need to do a flat tappet break in even if i just replace #1 lifters, right?

 

No, it's the cam that has to break in not the lifters.

Assuming you don' have any valve damage there's no reason you can't just replace the damaged parts. if it were me since this engine sounds questionable I'd just do what I had to to get it going and figure it's going to need rebuilt down the road a ways.

 

The cam and the lifters have to break in together. Putting new lifters on an old cam can be sketchy

 

Lifters really don't break in they should be perfectly flat and if they're not it's simply wear. new lifters on an old cam is common practice .

 

Lifters are not perfectly flat, they have a slight concave to them. It helps them rotate.Almost every instance of new lifters on an old cam I have heard of in the last few years have resulted in a flat cam and ruined motor. It's common knowledge the lack of zinc in todays oil leads to this. Not just on breakin but also over the life of the cam. I have seen it first hand twice.

 

Actually the lifter has a very slight crown to it , but if you look at it you're going to say it's flat because you don't see it . if it's concave it's really shot so toss it.

I've put new lifters on an old cam many times with no problems at all, if you lose the cam from it then you were going to lose it anyway. do your own research and you'll find it's an accepted practice, and I'm sure you'll
find some who take exception with it as you will on anything.

In my opinion the OP's engine isn't something worth putting a new cam in to avoid the .00001 % chance it won't accept 2 new lifters. it's a used engine of unknown condition so get it running and go with it. assuming it doesn't have other issues.

 

yeah, I'm not to the point of rebuilding this engine yet. I'll likely pop new lifters and push rods in. If I am pulling the engine, I might just consider a swap with another motor that was running when pulled. I'll update when I finally get around to this and will use plenty of assembly lube and zppd oil.

 

Per Motor Trend Mag.

Let us know if you use new lifters. If you think the motor is shot anyway you have nothing to lose.

Flat Tappet
Flat tappets have a time-proven performance history. They’ve won a lot of races and have served untold billions of people very well. The flat tappet advantage is less mass and weight compared to a roller tappet. Although it is easy to assume the flat tappet rides the cam lobe dead center. Nothing could be further from the truth. The flat tappet, be it hydraulic or mechanical, rides slightly to one side of the cam lobe, which causes the lifter to spin on the lobe for more uniform wear. Flat tappet lifters are actually not flat. They have a slight crown on the face of the lifter. The cam lobe is machined with a slight taper, which causes the lifter to ride the taper allowing the lifter to spin as it rides the lobe.

Where flat tappets get into trouble is oil starvation, improper valve lash adjustment, excessive valvespring pressure, and/or improper break-in. A flat tappet cam’s most critical moment is during that first firing. You must have a zinc additive in your engine oil to enable the tappets to work-harden the cam lobes so they will live a long time. Torco Break-In Engine Oil (SAE 30) for engine builders contains zinc and other additives important to proper cam lobe work-hardening during that critical first firing and break-in. Fire the engine and let it run at 2,500 rpm for 30 minutes to work-harden the lobes. Continue to run a zinc additive or a diesel-specific engine oil after the break-in.

And one more thing. When you’re installing a flat tappet camshaft, use the correct assembly lubricant. Cam journals get engine assembly lube. Cam lobes get moly lube, which is that charcoal gray slippery stuff that helps tappets work-harden the cam lobes. Flat tappet cams are more affordable than their roller counterparts. This factor makes them more appealing going in. However, the benefits of low cost in the flat tappet cam are quickly forgotten when you learn the benefits of a roller tappet cam.

 

thanks for the tips. I've broken in a flat tappet before (289 HiPo for my Cobra replica) and will get some break-in oil. However, if cam lobes are already hardened, do you really need to go through the entire break in process? I didn't know about the moly lube. I'll make sure I pick some up. My understanding is that there is no valve lash adjustment on the 351m, is that correct? you just tighten down the rocker pedestal to 18-22 ft lb torque? FWIW, the old lifter did not seem to have any crowning or concavity to the bottom of it. It looked pretty darn flat, which I suppose is a good sign.

 

Correct on the torque., I'd still add zinc for sure. The zinc continues to conditon the cam even after breakin. Definitely do the breakin proceedure!

 

I oil them good by just pouring oil over the top after they are on the cam, in the lifter bores with cam assembly past all over the bottums and slathered all over the cam loabs. There is no adjusting, the lifters will tick at initial start up but will self adjust as the oil pressure pumps them up to fill any excess lash. Before putting a lifter in an engine, one should make sure the lifter is just oiled, but NOT full of oil. Lifters will only pump to fill according to space as allowed when on the came base circle, they will not pump a valve open with oil pressure. Every time they open a valve, they might loose a little bit of oil like a 15th of drop maybe, but then they get to rest untill next time a loab bumps them, and that rest period of no load is when the fill to take up any slack that might then exist ... again. Really good lifters will not leak down, they just stay full cycle to cycle. Worn high miles lifters might leak down over time, but when the engine runs and oil is under pressure, even they will usually stop ticking pretty quick.