Valve interference with piston

[83Blzr62]

Is there any way to adjust the vavles so that they will not go down as far without using the thicker head gaskets? I think that might be causing the ticking sound that I have in my rebuilt engine. I checked lifters, injectors, and for exhaust leaks. During the engine build, I had to get a head shaved twice because it got damaged after it was shaved the first time and there was a gouge right were the firing ring was on the head gasket. Therefore I think my heads might have been shaved too much. Also the block was decked .005" and the piston was shaved .020" for lower compression. I do not know how much was taken off of the head though.

Thanks,
Kyle Karlson

[JohnC]

Unless the lifter is bottomed out there isn't much you can do that will have any effect. If the lifter is bottomed out the compression will go to hell in a handbasket as the valves won't close completely. What you're looking for is a way to reduce lift. A cam regrind could do it...

[DmaxMaverick]

......As would shimming the rocker assy or shortening the valve stem.

[EWC]

I have a Crane Cam regrind that " lost " .030" off the base lobe after it was done . You could also get shorter push rods . If you think the valves are hitting the piston , take a valve cover off and check around TDC by pushing down on the valve . Most race engines like to see .100" between piston and valve . I'd check both valves to see what clearances you have .

[JohnC]

......As would shimming the rocker assy or shortening the valve stem.


No. The lifter would pump up to compensate. The cam lift is what controls the valve lift. If the lifter reached it's limit then the valve lift would start to decrease, the ticking would get louder and back to hell in a handbasket...

[More Power]

Is there any way to adjust the vavles so that they will not go down as far without using the thicker head gaskets? I think that might be causing the ticking sound that I have in my rebuilt engine. I checked lifters, injectors, and for exhaust leaks. During the engine build, I had to get a head shaved twice because it got damaged after it was shaved the first time and there was a gouge right were the firing ring was on the head gasket. Therefore I think my heads might have been shaved too much. Also the block was decked .005" and the piston was shaved .020" for lower compression. I do not know how much was taken off of the head though.

Thanks,
Kyle Karlson

Trim the ends of the valves or, as DmaxMaverick suggested, shim the rocker shafts.

Jim

[83Blzr62]

Okay thanks for the help. I will try to shim the rocker arms about .020" and see if it goes away thanks for the advice.

-Kyle

[JohnC]

:rolleyes:

As long as you're in the range the lifter can accomodate, usually around 0.100, shimming and trimming won't change anything. Once you leave the range of the lifter, it's not "zero lash" any more and wear will accelerate.

[Robyn]

Tell me more about this ticking sound. Is it engine wide as in a lot of lifters making noise or more singular???

If the valves had or were hitting the piston you would know it post haste.

The extra thick gaskets are good for a .010 shave on the heads. The lifters will handle that with ease. The issue is to handle a block decking and there is where the thick gaskets are designed to come into play.

Does the engine run ok (smooth)

Let us know more info.

Robyn

[arveetek]

I don't think it's possible to have a valve hitting a piston if you shaved the pistons .020". That's what I did on my engine as well. In stock form, the pistons actually protrude out of the top of the block a small amount. After shaving the pistons and decking the block, my pistons ended up being recessed a little.

If a valve was hitting a piston, you 'd probably end up with damage pretty quick that would make a rough running engine.

I'd look elsewhere for your noise problem.

Casey

[john8662]

Cylinder head remanufacturing involves several processes, but here is the skinny on one that is remanufactured correctly (the highlights necessary).

Surface the deck of the head, take a maxium of .012" off the heads, after that they're too thin. There is a specification in the book as to where to measure heads that have already been shaved to figure out how much material is remaning. Near this point when they've been shaved issues like intake manifold bolts not wanting to go in on both sides becomes an issue.

Correct valve seat sealing surface and retain correct valve depth into the seat pocket from the flat fire deck. This is accomplished by narrowing the seats, many times they are within specification, there is a range. The intake seats see the most wear. The valves are ground and the seats setup to match, and be close across the board (all valves). Seats and valves replaced as necessary

Adjust the stem height and spring pressure on the top side. Because the valves are ground and because the seats are ground as well, the depth changes, which increases how much stem approaches at the top. The stem is ground and shortened so that another specification for stem length can be set (measured from a specific location).

Among other things, renew the valve guide liners, install coolant sleeve between valves, test springs and shim for correct spring pressure as necessary to equal them out.

These heads are very specific to remanufacture because they have non-adjustable rocker arms, so everything had to be according to specification to work. They're a mechanics dream (just bolt them on) but more work for a machinist.

So, if an engine has .020" cut pistons, that would mean that piston would be approximatly .014" in the hole, below deck height. A factory piston is supposed to protrude .005 + or - .001" Usually around .006" for standard compression.

Since you cut your deck .005", just subtract that from the amount. Your pistons should be close to .009" below the deck now. You can measure this with the piston and rod assembly in the bore and getting the piston at TDC, measure with a cylinder bore bridge and dial gauge, after zero'ing.

Forget about the valves being closer to the pistons due to them being shaved. If the heads are properly rebuilt (adjust the height and dept accordingly) the valves will not be any closer to the pistons than they were with a new head. You'd need to verify what was done to the heads, you can also measure yourself how much valve recession you have on the reman heads.

The only difference with shaved heads is that your distance between the lifter socket and the rocker arm socket has decreased, by the amount of material removed from both the head and the cylinder block. A .010 shorter pushrod might not be a bad idea, but this is still within the range of the lifter (by design), but...


EWC,

A longer pushrod might be needed for the Crane aftermarket or Diesel Depot camshaft, as they're ground stock cams They're now less .030" you say? Good info! I've got one of the cams to install, but have leary after DieselDummy told me that he had issues running one in the form of pushrods coming out from underneath the rocker arms, several times.

[EWC]

I measured the base lobe on the regrind and a stock cam , .030" smaller diameter . Now I can't comment on if the cam even works as I'm still putting the engine together . As far as valve jobs , you are supposed to measure the amount taken off the seats and then grind the valve stem down but not too far as the tips should be hardened . I think .010 was max . Still think my way is best , TDC and a little before and after . If you can't push down on the valve , you don't have any clearance . Want to measure the clearance ? Put a feeler gauge between the valve and rocker arm . Even if the heads were surfaced twice and the valve job , etc , you are still talking about having only maybe .030 - .040 clearance with a running engine that's not had any work done to it . I can't see where the clearance is that close in a production engine .

[83Blzr62]

John-

The heads were rebuilt, then I got them and some how during the time I had them one got gouged where the firing ring was, so I got it shaved. I was in a hurry, because I was trying to get the engine in my daily driver done, so I just trusted that they did the valves correctly after shaving the heads. Now I am thinking otherwise.

Robyn -

It is only on the passenger side. It is loud when it is coldest and hottest. In between you cannot hear it very well. It sounds like it gets louder with RPM. I used a stethescope and found it to be loudest on the number 8 cylinder and it is definatley metal on metal sound. I tried new lifters, checked and moved around injectors and looked for exhuast leaks. I have found nothing. I was just trying to find a quick and easy way to rule out the valve interference with the piston. I think I will try to get it warmed up and good a decent video of the sound.

-Kyle

[EWC]

Vacuum pump or pod ?