VCCA Home Forums TECHNICAL - 1945 AND NEWER 1971-1979 Camshaft troubles in 71 truck

Help! I bought a sweet old 71 Chevy Custom Camper 3/4 ton from a 93 yr old man who babied it. it has a 350 and 106K original miles and not long after I got it the cam went flat on 3 lobes and one more well on the way. I put a new cam in and have had to readjust the valves now 3 times and there is a metalic look to the oil when I change it. I only have 4000 miles on the new cam and suspect it is going south already. I talked to a friend who knew someone with a 396 camaro who only got about 1000 miles out of his replacement cams. He said Crane gave him a new roller cam to solve the problem after his car ate 2 cams. Crane said it was bad cam blanks from China (figures) and all the cam companys are buy the same blanks. I don't want to have to put cams in this thing every few thousand miles. Outside of this cam problem the engine runs super nice and was very clean inside! Has anyone else had this problem or would there be something else causing this.

The problem with "China" cams has come up before. A good brand of a US made cam should solve the problem along with using a cam break-in additive in the oil for the first 2000 miles. There is also some "soft" lifters out their that can damage the cam lobes.

I was involved with an engine job when I still had my shop, it happened to be a 47 Fleetline with a 350. The customer had a friend build him a new motor and install it. It was brought to us for AC work and he asked me to check the valve adjustment, cam was already bad, less than 200 miles. The next cam and lifters did not last an hour before they were bad. The next cam and lifters were name brand and used proper oil additive, EOS from gm not sure if its still available, MOA from BG is. Be careful to not buy the cheap junk.

In years past I used Crane cams almost exclusively and never had a failure. but I guess like many companies they've gone off shore to save money and it's biten them. following Crane's recomendations for intitial breakin is very important. I always used their assembly lube and breakin additive in the oil. the first 20 minutes running is very crucial for good service. in the early 80s GM got a hold of some bad cams. Mine lost a lobe at 38,000 miles in my Blazer.

I have a '69 Nova w/350 out of '75 Chevy pickup sitting in my garage with a loud lifter knock that I am not sure of what the cause.

The story goes back in '95 I rebuilt this engine with an Edlebrock Torker Plus Camshaft package and at 2500 miles I had a light popping back in my carburetor. Suspecting a stuck valve or something I removed the valve cover to take a look. As it turned out I had a rocker arm just barely lifting, so the dial indicator that I had ready to check the lift with wasn't necessary. It was the exhaust valve on the #3 cylinder. I removed the cam and sent it back to Edlebrock with a nearly round lobe. After about a month or 2 of non-response, I am fairly patient , I called them to find out what the determination was going to be. After looking around for the cam and as I recall a request to call me back in a little while after they found the cam and related info. They called back and told me that it must have been my fault because they do not and have never made a soft cam. Plus I received a story of how they have engine builders that do nothing but build engines for them and they make mistakes and lose an engine at least once a year. I was told that I must have failed to hone the lifter bores thus the lifter did not rotate in the bore and wore the cam out. At this I informed them that I had honed the lifter bores and that I had the lifter that I would send them that was also worn in a perfect concave pattern not a straight groove from being stuck. They at that point said they would talk to their technical department and would get back to me. They called back about an hour or two later and said they would send me a new cam package.

I got tired of waiting, so I had already gone out and purchased a new Edlebrock Performer Plus Camshaft package. I installed this cam and it ran great for about 4500 miles, that's when the loud knocking started. I believe it was again on the #3 cylinder. At this point I thought that I might have been too generous with the RTV, as I had seen this happen before, and a small piece broke loose and stuck in the oil port of a lifter causing it to collapse. I removed the intake and the lifters and they were all OK. None were collapsed. I put it all back together to the point I was ready to adjust the lifters and that is were it is setting in the garage to this day that was about 2002, as I said I am patient . I now believe that I may have a problem with the valve spring. I replace everything in this engine with quality parts and had the machine work on the head done by a local machine shop that does excellent work (Woodruffs in Odon, Indiana). I did not see anything wrong with the springs but having had plenty of time to think about it since then. I did not remove them and 1 may be cracked, allowing the lifter to hammer. I plan on checking it out this next summer.

So, I have had a cam lobe round off for no good reason and experienced other problems that I am not yet sure of the cause. I do have a brand new Torker Plus camshaft package if I ever decide to build another engine.

Hi,

Don't mean to hijack your thread, but an important point needs to be made.



I'm sure that the graduates of the "School is in Session" know how I felt about RTV. It has no business in the shop and should be removed.

Yes, Ray, you and I have gone through this before. If you will go back and read my old posts you will see, if you don't remember. I was hesitant to bring it up due to that whole ordeal, but was trying to offer some insight here. I still stand my ground that used properly its better than any gasket hands down. The funny thing is fifteen years ago I was of the same opinion as you, but seen the light. Maybe you will too some day. Stay away from the old blue it still stinks. The new stuff used properly has a sweet aroma. No it still physically stinks, but it works wonderfully.

Scott

Hi Scott,

My position is motivated by two horrible incidents.

1. Changed the fuel tank in a Toyota RV. I used some around the new pickup tube and fuel gage sender. It ended up in the Chevrolet garage in Moab Utah. Tank was removed and a glob of the RTV removed from the end of the pickup tube. Removed all traces of the RTV and it is probably on the road as we speak.

2. I used some of the stuff in the 4 corners of my 1925 Roadster pan. Sometime later I noticed my oil pressure was gone. Pulled the pan and discovered a glob on the end of the oil pickup tube.

Don't have any plans to test it further.

Ray,

Then you should hold to your boycott of RTV.

I am guessing that the RTV you used was the old Permatex 6B which turned to snot in gasoline. It should never be used around gasoline connections, and as far as I am concerned, anywhere else because it tended to do the same in oil. However, the new RTV's mentioned by color and number in the Oil Pan Gasket post #125941, awhile back are excellent. These as mentioned in modern engines are a must as many applications do not even have gaskets available and will require the use of sealers to restore the Chevrolets of tomorrow. My point is, to catagorize something as evil just because of a bad experience or 2 with one type of that product, especially in its infancy, is wrong. I have had bad experiences with Quaker State oil in 305 Chevy engines should I not use Quaker State or any oil at all for that matter. Hope you can see my point and I really am not trying to be a butt.

Your info about the experience of using around gasoline I find quite useful and should be heeded by all who use RTV's. The Info of over use of RTV's I find quite useful. I had the above mentioned experience of finding collapsed lifters in a couple of engines that someone had over used RTV and man does that old blue snot migrate. On the other hand I used the Ultra Grey 599BR on my Toyota Corolla when changing the timing chain and gears at 356,000 miles and it now has 393,000+ miles and is still dry as a bone.

Lastly, These sealers should not be used on our old Chevys to keep them as authentic as possible. I appologized for this before when I gave advice to Chevylover51 that he could use just enough RTV to hold an oil pan gasket in place while he assembled it.

Scott

Hi Scott,

You make two very valid points.

1. The previous post was in reference to the Blue snot.

2. When working on the newer stuff several gaskets have been replaced by the modern RTV. Stuff designed for this newer application is superior to the old Blue stuff. To be noted is the special lip, on for example, the new valve covers that are shaped to used the newer RTV and no provisions for a gasket.

Thanks Ray. Thats all I was really trying to say.

Scott

You need to break in the cam with diesel oil since oil for pass cars had a formula change and zinc was severely reduced and will kill new cams,the EPA made them do it and since most newer vehicles have roller lifters the new oil is fine but for those with the non roller lifters the new oil can be a major problem with break in. Jeff

Use cam break in lube. Diesel oil now has the reduced levels of zinc.

When I was working one of the company shop mechanics replaced the gas gauge sender in my 1990 Caprice company car with a 350. He used the good RTV to seal the top of the tank where he cut a 3" hole with a hole saw, don't ask me why he had to cut the hole. When he ran the screws in to fasten the cover he pushed little RTV rat pills into the tank. all six of them stopped up the fuel line at the fuel filter and cut the power to about half, then it quit all together. I still use the stuff, but I am very careful!

Just another reason to keep it outside in the shed.

Sounds like because he had no clue what he was doing. It would have been much easier to have undone the lock ring to remove the sending unit. Then he would have only of had to use the oring that is provided to seal the tank. Even if he for some reason felt he had to tweek the unit to get a proper reading a few trial and error attempts would have been far better than to create a potential leak area that was sealed with a product that states DO Not Use in locations where continuous contact with gasoline will occur.

Yep, the "mechanic" definitely had no idea as to what he was doing. Most everyone knows that you don't use RTV anywhere near gasoline.