78 P.C. L-82 Strange Engine Noises

[Clem Z.]

Re: 78 P.C. L-82 Strange Engine Noises

could the rebuilders installed "self aligning" rocker arms ??

[Stuart F.]

Re: 78 P.C. L-82 Strange Engine Noises

Good points clem and Bill. I hope to get into it as soon as my son is available (had to take his family on a mini vaction b4 school starts again).

Bill with the questions you ask, are we looking for improper adjusted rockers with hydraulic lifters bottomed out or not engaged (? Term?)? Are we looking at a condition that could wreck the cam?

Stu Fox

[William C.]

Re: 78 P.C. L-82 Strange Engine Noises

Fundamentally I'm just trying to get any grip on what the source is. If you have not adjusted the rockers to spec, It would eliminate one issue, as well as allow you to look for anything amiss under the rocker covers, inclufing contact between the rockers and the covers. Are stock rockers even in place?

[Clem Z.]

Re: 78 P.C. L-82 Strange Engine Noises

Fundamentally I'm just trying to get any grip on what the source is. If you have not adjusted the rockers to spec, It would eliminate one issue, as well as allow you to look for anything amiss under the rocker covers, inclufing contact between the rockers and the covers. Are stock rockers even in place?

just feel the rocker cover and you will feel it if the rockers are hitting the covers when the engine is running. i remember some some chevy covers if put on upside down the rockers would hit the covers

[Stuart F.]

Re: 78 P.C. L-82 Strange Engine Noises

Interesting points Clem and Bill. I never experienced such an event, but I'd say it sounds quite possible in this case. It has the aluminum covers (stock L-82) and, as I recall, they usually are reapplied with just a bead of silicone and not a gasket (we fixed one leaker on a previous P. C. my son had). If the shop put on aftermarket rockers (not sure) or push rods (sure) I can see how this may be possible. My concern here would be for cam or lifter damage, of course. Sure hope I get a chance to see it again soon. I'm anxious to take a look.

Thanks for your ideas. Great!

Stu Fox

[William C.]

Re: 78 P.C. L-82 Strange Engine Noises

Not sure about '78. but Mid-year aluminum covers used gaskets. Also some mid-year valve covers must be installed in one orientation, or the rocker arms interfere. Not sure about the later versions.

[Stuart F.]

Re: 78 P.C. L-82 Strange Engine Noises

Bill and Dave;

Thanks for your ideas. I have a lot to work with here. My son knows a lot about detailing already good cars, but has not had more than a valve cover off an engine and, in that department, he's a bit naive - impressed by all the receipts and outside appearance of the engine. I just hope he didn't get burned on this one. Wish I had been with him on his first inspection of the car as I would have told him "NO"!. But, we'll make the best of it.

Thanks again.

Stu Fox

[Steven B.]

Re: 78 P.C. L-82 Strange Engine Noises

Stu, I ordered a '77 L-82 new and my dad and I ordered a '78 L-48 new and still have them both. The L-82 does make more internal noise when new, although I don't know if comparable to yours, due to being put together looser than the L-48. I have the clearance numbers around here someplace and will look for them. The sound when new was like piston slap. There was also more valve train noise than an L-48.

Steve

[Stuart F.]

Re: 78 P.C. L-82 Strange Engine Noises

Thanks Steve. That's encouraging. I hope that proves to be the case with this one. My son just returned today and he will contact the mechanic at the shop that did the work. He was very forthcoming before my son bought the car by providing faxed copies of all the receipts, and will probably answer our questions - those we didn't know to ask before.

If you locate the specs, we sure would be interested.

Stu Fox

[Timothy B.]

Re: 78 P.C. L-82 Strange Engine Noises

Stu,

Isn't there a Rhodes hydraulic lifter that adjusts without preload so it does not pump up. If you find the lifters have been replaced you may want to investigate further.

[Clem Z.]

Re: 78 P.C. L-82 Strange Engine Noises

Stu,

Isn't there a Rhodes hydraulic lifter that adjusts without preload so it does not pump up. If you find the lifters have been replaced you may want to investigate further.

those lifters make a ticking sound like a solid lifter setup. a diesel sound is more of a klunk sound

[Steven B.]

Re: 78 P.C. L-82 Strange Engine Noises

Thanks Steve. That's encouraging. I hope that proves to be the case with this one. My son just returned today and he will contact the mechanic at the shop that did the work. He was very forthcoming before my son bought the car by providing faxed copies of all the receipts, and will probably answer our questions - those we didn't know to ask before.

If you locate the specs, we sure would be interested.

Stu Fox

Stu, I will continue to look for the specs. I have nearly 200 banker boxes and have gotten through a handful so far. I used to know the difference in the specs but memory fails me now.

Steve

[Stuart F.]

Re: 78 P.C. L-82 Strange Engine Noises

Thanks Clem, Tim and Steve for your continued thoughts. One thing I learned from my son this morning is that the detailed receipts he has referred to an "overheating" condition. He will try to get more information from the mechanic, but whether the man recalls any specifics about the car is a long shot. History of the car is typical of a low mileage 78 P.C., i.e. accumulated only 42 miles from 1978 through 2001, then sat again from 2003 through 2007. It now has about 8000 on the odometer. So it has been neglected. There are a lot of details on the car that speaks to that mileage, but a lot of signs of neglect. Typically, the emblems paint is faded, yet their are no pits in the chrome. The decals too are weathered, but the paint is pretty good and all the weather stripping is great. The undercarriage is one of the cleanest we've seen. It could be easily restored, but we have to address the mechanicals like this dieseling sound. To clarify again; this is not a typical valve train noise - no ticking, rather a very metallic rattle - steady everywhere across the engine. i'd swear I was standing next to an old Olds 350 instead of a Chevy 350.

Stu Fox

[Stuart F.]

Re: 78 P.C. L-82 Strange Engine Noises

So what is the latest conventional wisdom on adjusting hydraulic lifters on a 78 L-82? My son is convinced that we should give that our first shot as the boys at a local hot rod shop listened to it and that was their opinion. Like I said, my last Chevy V8 experience with hydraulics was in about 1056.

Manual says to spin pushrod until it stops, then go one (1) more complete turn to engage the plunger. Does that sound about right? Any variation for a 78 vintage SHP like the L-82?

Thanks in advance for any input.

Stu Fox

[William C.]

Re: 78 P.C. L-82 Strange Engine Noises

warm the engine, remove one valve cover, start the engine and see if you have an oil containment problem, if not, back off one rocker at a time unitl you hear at "rap-rap-rap noise then tighten until the noise just stops. Go 3/4 turn down from that point and wait for the engine to recover and smooth out, then repeat for the next valve until you run out of valves on that side, button up and repeat process on opposite side. If you have too much oil flinging about, you can make a shield for the oil hole in the rockers from an old steel valvecover. Not too difficult.