Camshaft troubles 71 Chevy truck

Has anyone had problems with replacement cam shafts lately? Just replaced the original cam in my 71 chevy 3/4ton becuse it had 3 flat lobes and I have had to readjust the valves now 3 times and the oil has a metallic look to it when in the sunlight in the drain pan. Only got less than 4000 miles out of the new cam and yes, it was put in right. I heard something about the cam blanks are now all made in CHINA and all the cam companys use those blanks. Anyone else had problems?

Are you using diesel oil for breakin?

I used a graphited Cam assembly lube and the red assembly lube that came with the cam. Lifters were all primed before installing. I am running a HD 30 wt oil that is good for non turbo diesels or gas engines in summer heat and 10-40 at last oil change 20 miles ago. By The way, a few weeks ago when the weather was real cold I drove it after warming up some and now the oil pressure gauge is reading low at idle and at half at 60 MPH. It is the factory gauge so I am going to run a test with another guage to check that out. It doesn't make any different noises that it did before. I just hope that metal from the cam didn't mess up the oil pump. The gauge that day did read all the way up(higher that it normally went) when I looked at it after a mile or so that cold morning so maybe it just tweaked the gauge. It is making lifter noise a little bit but was doing that before the cold morning.

By the way, this engine is stock original unrebuilt 4 bbl with A/C and is not been messed with. Everything is hooked up like it is supposed to be and working. It has about 106K original miles and was very clean inside when I put the cam in. The 93 yr old Farmer I got it from is a maintenance stickler!

If you started the truck and just let it run at slow idle there is a good possibility that the new cam is wiped. It should have been run at 15-1800 rpm for at least 15-20 minutes to seat the lifters to the cam. Your low oil presuure might be from all the metal that has been in the lube system wearing out the bearings.

Ouch! Sorry to hear that Bob.

I wouldn't even mess with the oil pressure guage, 'cause you're gonna find the bottom end has been wiped out too.

Cheapest way around this is a Good Wrench crate engine.

Allan

I am just finishing building a 350, nothing exotic just a normal engine. However since I started with just a block I put in a COMP CAM camshaft and was told by the representative that EPA has put restrictions on the oil companies such that they have changed the make up of the oil and in a non roller application the chances of wiping a camshaft are very high, to the point of certainity. I did what I had to so a roller lifter would work.

As previously stated.With that much metal floating around and the oil pressure.It's time for a 100% tear down, pull every oil gallery plug and rifle brush them. Or a Good Wench crate engine.

im wondering what brand cam you used, not that it makes alot of difference.. a few years ago there was info being presented in rebuilder and motor magazine that a additive used in dino oil was being phased out because of the use of roller cams in newer designed engines.the additive was for the flat lobe camshafts used before roller cams became the norm. i started useing synthetic in my old stuff because of that.

Here's a portion of the Comp Cams tech bulletin on flat tappet cams.

As we touched on earlier, another major factor in the increase of flat tappet camshaft failure is
your favorite brand of engine oil. Simply put, today’s engine oil is just not the same as it used to
be, thanks to ever tightening environmental regulations. The EPA has done a great job in
reducing emissions and the effects of some of the ingredients found in traditional oils; however
these changes to the oil have only made life tougher on your flat tappet camshaft. The lubricity
of the oil and specifically the reduction of the important anti-wear additives such as zinc and
phosphorus, which help break-in and overall camshaft life, have been drastically reduced. In
terms of oil selection, we recommend a high “ZDDP”, Zinc Dialkyl Dithiosphosphate, content
oil for the break-in procedure and regular operation. There are several companies that are now
offering specialized “race/off-road” oils, high in anti-friction and anti-wear content, to combat
this specific problem. These oils carry the SL rating and contain up to 1000 ppm of
Zinc/Phosphorous (the Zinc content in today’s “off-the-shelf” oils have been reduced upwards of
20% since 2001 and approximately 35% since 1997).

I wouldn't be worried about who made the blanks. Once a camshaft is ground, it is surfaced hardened with the Parkerization process. That is what makes, or breaks - a cam - along with how well the installation and break-in is done.

Back in the 70s, General Motors claimed that most of their cam-failures were caused by improper break-in at the factory, not a bad hardening process. True or not, who knows and who cares at this point. Back then, we usually repaired engines with replacement cams from Crane Comp., and few other aftermarket companies. I've never had, nor have I seen, a failure problem with any of the afermarket cams when done right.

But now adays? Can't say.

In regard to engine oil, even the automotive diesel oils have the ZDDP anti-cam-wear ingredients lowered for removed. Only the racing, tractor, or European oils still have it.

Did you put in new lifters or use the old ones? The old ones can wipe out a new cam.

The old ones were trashed badly. new ones came with the cam kit.

I was thinking that also about the heat treating being done after the cam is ground, but if the blank has a flaw in the metal alloy I was thinking it could affect the hardening. Dunno, but food for thought.

I"ve built many Chevy 350 engines and never had any come back. When I build one, I prime the oil pump with a primer tool I made from an old distributor, and yes, keep the rpm"s up and varied on first fire-up. Also, change that oil out after break in.

The oil I use is HD 30wt "rated for farm and fleet over the road Diesel and off road construction equipment and has heavy duty additives for non forced lubrication of high pressure load valve train parts". It is API SH/SJ.

Yep, I varied the rpm at start up and although I didn't prime the engine itself ,Didn't need to in this case, I did pre lube or fill up the lifters with oil before installing. The first oil change was about 500 miles and had that metallic look to it, but I figured it was the graphite cam assembly lube washing off. nothing feels gritty in the oil.

Hi Allen, Hope the bottom isn't trashed! OUCH! It doesn't make any loose or knocking noises at all. It sounds sweet as a new one outside of the lifter clack after a few miles from adjusting. She is a real nice ol truck,one heck of a firewood hauler, I can pile it up to the top of the cab with tightly stacked in oak/ hickory and she just barely sits low in the back and drives just as good as when empty. The original owner took real good care of it and nothing has been hacked on it. Heck fire the A/C still blows cold and the original cloth seat isn't ripped. The doors do have some rust in the bottoms but the rockers are still solid as a rock. Get this, if the fan is on high and the windows rolled up, it is hard to close the doors, the cab is that tight still! The old guy I got it from thought enough of it to put 4 new Michelins on it but he didn't skimp on any of his equipment. The only thing I don't like about it is the 10-11 MPG it gets, but I don't drive it everyday, just when hauling or towing the trailer.

What did you have to do to go with the roller cam? I know the roller lifters have a tie between them to keep them straight, but do you have to machine the block to clear the tie bar?

Bob,

Over the last 10 years, I would estimate my buds and me wipe out roughly 1 in 20 cams. Most of us are quite picky on assembly and break-in.
Last two cams I wiped out were a 292H comp cam (hydraulic) and a 298HR hydraulic nitrous roller cam. Comp cam gave me a new roller cam on the second time.

As others say, I would pull the engine and flush everything. You said you pumped up the lifters, so I assume its a hydraulic cam, not a solid (flat) cam. Make sure you have oil with high ZDDP. I think you can buy it as an additive. I can't find last months Hot Rod mag. Big article on this exact subject.

Or... you could just buy my motor pictured here... just leave the hood off the truck. Oh yeah, it has a new hydraulic roller comp cam in it too!! It's a mild 454 Chevy. Getting ready to hopefully replace it with a 632 inch Chevy.

Good luck. Let us know how the next break in goes.

Rick

On an SBC, while the engine is still on the stand, I ALWAYS patch in an oil pressure guage and spin the oil pump till pressure comes up, then keep spinning for another five minutes or at least till all the rocker arms are oiled. They make tools for this, but I just use the shaft out of an old distributor.

For engines where you can't just spin the oil pump, like the GM 3.8, I have a humongous old 1/2 inch electric drill that will spin a fresh V6 with the spark plugs out at idle rpm to do the same thing.

On flat tappet racing cams, Crane says not to idle the engine below 1400 rpm for the first two hours. That's good advice for any new cam, including hydraulic or rollers.

Don't git trigger happy with the HO-Made tool,,, it will break the plastic connector tween the oil pump and drive shaft but if you use the metal connector spin'er up,,, I just replaced a cam last week in a 350,,, first one i have seen bad in a long time,,, i also spec its the first time its seen a oil change in a long time,,, owner said he has never changed the oil since he brought it a year are so ago :roll:

You're going to want to pull that guy and open her up to clean things out. Those metal bits end up in the screen of your oil pump pickup tube sump and end up plugging it up, next will be spun bearings. I hate to say it, but if its me that engine's coming apart and the plugs are coming out on the end of the block and its getting rodded with a wire brush (gun cleaning kit), then its getting flushed, hot tanked and rebuilt. I'm sorry, times are tough, cash isn't readily available to many including me, but the cost of having a crank welded up, ground down, and rods resized or replaced after spinning a bearing, and the other damage caused is just going to cost even more $$$.

You didn't say small or big block though. I did a friend a favor one time and really screwed him royal. Had a '70 402 and needed a new hydraulic cam quick, and I just happened to have a mildly rougher street Crane Fireball still setting in the box. It was for a '67 or '68 427, which isn't and is a problem. There was a change in lubrication on the rear journal in '69 which meant that you couldn't use cams from '68 and prior without modifications. '68 and earlier cams had a big groove (very noticable) cut around the whole diameter of the last journal for oiling, but the bearing itself had a very small hole, like 3/16" that worked like a dam to regulate the oil flow. That design was changed in '69 whereas the rear cam journal didn't have that groove, and to compensate, Chevy put a huge hole in the bearing itself for oiling. If you use a '68 or earlier cam in a '69 or later big block, you have to solder that hole shut in the bearing, and then redrill at about 3/16" of an inch. Failure to do so...bad news. Very bad news. Combine that big oiling hole in the bearing with that big groove around that last journal, and you will lose almost all oil pressure to the rest of the engine. I knew that, but didn't think about that when I gave my buddy that cam...for free, and when he put it in that freshly rebuilt 402 and fired it up, no oil pressure and it became scrap in seconds. He had no idea what happened, but after he told me about it, what happened took about 3 seconds to register...I screwed up doing a friend a quick off the cuff favor late one night when he came over and needed one.

Mark

Thanks guys! I may have figured out the problem. When I first started it I noticed that all the pushrods wern't turning but I loosened up the adjusters on those rockers and got them going but they stopped again or slowed way down when I tighted them back up. I looked on Cranes website on cam failers and they say they MUST rotate or they will fail. The cam came from Carquest and was just a stock replacement. I wonder if the taper on the journals wasn't gound enough to cause the rotation. The cam I took out had some lifters that hadn't rotated either and had groves wore in the bottoms from sitting in one place. It was a GM cam and I think it was the original. I guess I better find out what would cause the original lifters from rotating and why the replacements didn't either. It is strange since this truck was never abused.

Wow! nice motor! It might be a bit much for fetching firewood though, hehehehe!

Are you planning on only dropping another cam & lifter set in?