Help with rocker arm or lifter problem ...PleaseI've read the previous threads on this subject and I guess I'm still confused?
just rebuilt engine a 351 m. Sent block out and had it bored 30., new pistons cam and lifters as well as bearings, chain and gears. Heads were good so just went with new seals. Problem after starting was noise from lifter/rockers ? Removed valve cover and found 2 rockers that won't tighten enough? 2 different cylinders....of course the valves are not opening enogh. Checked and swapped push rods and rockers and no change Have good oil pressure and if I temporarily placed a shim between rocker and valve stem. It appears to move the valve open the proper distance
The threads I've read talk about push rod length and/or machining the rocker mounting surface in order to be able to snug the rocker tighter???

Before tearing it back apart has anyone have an idea

 

you need to measure your pushrods since it sounds like you haven't. but first when you say " not opening the valve enough " do you mean that literally ? because if you're not opening the valve enough you may have eaten lobes on your cam during break in. check your oil for metal. if you mean it's just clicking because of a slight amount of slack check your pushrod length.

Pull one of the cylinders you're concerned about up on TDC compression and with a pushrod length checker see what it is at zero lash. then add your preload to it and that's the pushrod you need for that valve. hopefully you can check one that's ok and you'll be inside your preload range. if not you have other problems.

Assuming you just have a length problem that can be cured with a custom set of pushrods that's common .

 

You said it was just the seals replaced on the heads. So no new springs, no new retainers and no new valves. Correct?
If none of that other stuff and the machining done on the surface of the heads was either minimal, or not performed at all, the pushrod length changes "should" not have been necessary. At least not always.

But I'm worried about the cam too. As 440 said, did you perform the mandatory cam break-in procedure immediately upon the first firing up of the engine? And was a good assembly lube used on the cam and lifters during assembly?
Have also heard of many instances where the lifters were defective right out of the box, or failed in fairly short order. With any luck (so to speak) you may only be dealing with bad lifters.
We can hope anyway...

Good luck.

Paul

 

I used the supplied cam lube and the heads were Heads that came off the engine ( it was a reman that had a premature block failure and they were still good with low mileage) the replacement salvage yard block was done at a machine shop as a precaution.
when I say the valves are not opening enough it's because the play in the rocker arm is so excessive the rockers don't touch the valve stem. If a place a shim between the rocker tip and the valve stem it appears to open as much as the other valves

 

I fear you wiped some cam lobes during break in. Needs zinc additive and ran at about 1800 rpm for at least 15 minutes before idling. Also keep blipping the throttle gently.

Also if this happens to an engine you can forget fixing it. All the tiny pieces of metal have ciculated through the engine bearing tec. Have to teak down.


Good luck with it.

 

the cam lube helps but you still need a high zinc break in oil and you need to perform the break in procedure. and if you do all that you have a good chance of success but no sure thing. a sure thing is a roller cam and that's why I use them exclusively .

The reason it could be the cam is the slack you're talking about is excessive . if you can see the slack that's big. so what likely happened is you ate a lobe and as a result it cannot lift high enough to work and the slack you see is the result.

Milling the heads and decking the block make the pushrods too long, the opposite of your problem. so does valves sucking up into the head with wear. so to have extremely short pushrods defies most logic.

About the only things you can do it look at your valve stem heights , is there an extreme difference between the lose rockers and the others ? bad lifters are a possibility but unlikely this soon. you say you already swapped rockers so that eliminates extreme rocker wear.

Check your oil too.

 

I'm no expert but I just watched a video the other day that a guy had stuck valves that caused the press in rocker studs to pull out. I dont know if that engine uses press in studs or the likelyhood of that but thought I'd mention it.

 

An update..today I used an inspection camera and saw that the lifter was not coming out as far as the rest. Pulled the intake and found a dished out lifter. I removed them all and found wear on all of them. I then installed the old lifters for the sake of inspection and it appears to open and close the valves on all cylinders properly and I see oil pumping . . I am guessing that with this observation the cam is probably still good? I spoke to the machine shop today and I am wondering if the lifters they supplied me are any good quality.? I was very carefull to use the correct break in procedure. At this point I am just going to get her cranked back up and keep my fingers crossed

 

Hate to be the one to burst your bubble, but if the lifters are dished as you say, the lobes on your cam are flat.. maybe not to the point that it would be obvious if you pulled it out, but the surface isn't hardened..

There is no quick fix at this point.. all of the material off of the lifters has circulated through all the oil system, and any bearing has had essentially sandpaper run through it before the bearings could break in.. metal shavings are going to be embedded into the new bearings.. new bearings are susceptible to it vs used bearings, because again, they're not broken in and hardened..

Explain step by step of your motor break in procedure.. also, empty out your oil pan, and cut open your filter, to confirm what we are telling you

 

That is correct. if the lifters are shot so is the cam so you're screwed. pull the engine and tear it down and get it all cleaned out checked out. new bearings and gaskets will be what you can hope for at the minimum.

If you want better performance and you don't want this experience again use a custom roller cam this time . this is going to cost you many times what the extra money in the cam would have cost plus all the work. I've been through this just like you and it made a believer out of me.

 

Thanks for the info. I will check it out tomorrow.

 

I know it's a kick in the nuts, and not what you wanted to hear, but it's the reality of the situation.. flat tappet cams suck for this exact reason, oils aren't what they used to be, and sometimes they go flat because a mouse farted across your shop, even if you do everything right breaking them in.. one thing that can help, run an oil with higher amounts of zinc in it.. any good diesel rated oil is a good, cost effective solution to some of the higher end name brand oils.. Chevron delo 400 for example, it has around 1100ppm of zinc, which is the amount older oils had in it.. it says that in the material safety data sheet, (MSDS) which you can find online for any brand of oil you wish to run.. it's a lot lower than what diesel oil used to have in it, but it is sufficient for older v8s

X2 on a hydraulic roller camshaft, there are a multitude of benefits to running one.. the big thing, again sucks, don't cheap out on the lifters if you decide to run one.. in recent years, a lot of manufacturers on the lower end have had a bunch of problems with the rollers in the lifters seizing up and destroying the cam, or the oil bleeds off as fast as it goes into the lifter, not staying pumped up.. as to why that is, that's a whole other topic beyond the scope of this.. if your budget allows an extra $8-900, it is well worth the investment, as there is no more cam break in, just rings and bearings..

 

I think Brent charges $375 for a custom roller cam now and you can buy Lunati or one of the other high quality Roller lifters for around $425 so you should be into a custom set up for around $800 . I haven't priced a flat tappet in a long time but I think you're looking at a good $300 for cam and lifters so that leaves you with a $500 difference.

So a custom grind cam, no break in fails or drama and better performance for $500 ? no brainer in my opinion.