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New Cam and Rockers - odd looking at 500+ miles


inline6

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Those of us not running the stock dizzy do it with a modified oil pump drive with no gear, and a brazed on extension to get out of the timing cover. You still have to drop the oil pump to install the pump drive with the gear, but as long as the pump is full and the galleys are full and you're quick about it, it works fine.

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The last engine I built I had zero issues with cam/rocker break in. Here is the configuration:

 

New .530 lift Isky cam on new CWC blank, cryo treated

Isky cam lube

Resurfaced OEM rockers cryo treated with REM ISF treatment

Stock oil restrictors in E31 head

Stock early E31 spray bar (cam was also drilled for lubrication)

 

I primed engine on the stand with electric drill, distributor with guts removed, and distributor shaft with gear removed. This is extremely important as you can verify that all cam oil holes (both in cam and spray bar) are flowing. It can take upwards of 15 seconds to get oit to the cam on a dry engine.

 

I primed the engine with Valvoline VR1 (high zinc), and Redline break-in additive.

 

After a season of events, the cam looks beautiful. No signs of wear on cam or rockers. Since break-in I've only run Brad Pen 20W50.

 

Did you prime the engine? If not, I think this is what caused the damage. Most likely it happen after running dry the first few seconds after startup.

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Did you prime the engine? If not, I think this is what caused the damage. Most likely it happen after running dry the first few seconds after startup.

 

Cam had a liberal dose of Redline assembly lube.  Engine sat for about 4 months in my garage before I attempted to start it, but lube was in place when I went to start and it hadn't turned over until then.   As I described above, I pulled the spark plugs, then watching the oil pressure gauge, spun the engine over for something like 30-45 seconds continuously with the starter motor.  After the oil pressure needle started moving up the scale, I kept spinning for around 10 seconds.  I think it was under 45 seconds total, but don't know for sure.  

 

So, if this happened at initial start, it had to wipe the lube off of the lobes and not have oil show up for a while...  Based on what experienced builders have said, this is entirely possible and probably even likely.  It seems no amount of turning over before getting oil pressure is the best way to keep this from happening.

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Cam had a liberal dose of Redline assembly lube.  Engine sat for about 4 months in my garage before I attempted to start it, but lube was in place when I went to start and it hadn't turned over until then.   As I described above, I pulled the spark plugs, then watching the oil pressure gauge, spun the engine over for something like 30-45 seconds continuously with the starter motor.  After the oil pressure needle started moving up the scale, I kept spinning for around 10 seconds.  I think it was under 45 seconds total, but don't know for sure.  

 

So, if this happened at initial start, it had to wipe the lube off of the lobes and not have oil show up for a while...  Based on what experienced builders have said, this is entirely possible and probably even likely.  It seems no amount of turning over before getting oil pressure is the best way to keep this from happening.

 

When you prime the engine on the stand, you are not turning it over. You are just filling the oil galleys as if the engine had already been started. Once the engine is primed, it is ready to start.

 

For stock motors with stock cams and valve springs this doesn't matter. When you have a high lift cam, and matching  stiff springs, you have to go these lengths to ensure that the cam and rockers get broken in properly.

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Cam and rockers sent off to Delta cams.  Rockers will be resurfaced, we'll see what they can do on the cam.  I'm thinking best case scenario, they can polish out the lobes equally.  I think 2 thousandths would clean everything up.  

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+1 for Delta Cams. I have been to their shop and I use a re-grind cam they offer, with their rockers too. The cam now has 7k miles and no issues!!! On a side note, when I finished my engine assembly, I used a modified distributor shaft and a drill to pre-prime the oil pump and galley before initial engine start. Always a good idea!!

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On a side note, when I finished my engine assembly, I used a modified distributor shaft and a drill to pre-prime the oil pump and galley before initial engine start. Always a good idea!!

 

That's like three people who have done this.  I'm like Tony, I could never figure out how people were doing this with the worm gear on the crank...  but I understand now how this could be done if you make a special long shaft (no gear on it) that just drives the oil pump.

Edited by inline6
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Put the shaft in a vise loosely with the gear resting on top of the vise. A few good hits on shaft will drive it out of the gear. I did this many years ago and was amazed on how easy it was to drive it out. Then I gutted a distributor. I keep the shaft and distributor in a bag together so it is easy to find the next time I need to prime an engine.

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I just sent out another batch of rocker arms to Delta Camshaft this morning. Fixing to change out the cam in my Z from the Delta 0.455" lift 280* duration cam for an Isky grind for the blower, and even though the engine is still in the car and running, it'll get primed exactly the same as if it was on the stand...just seems like cheap insurance to me.

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  • 1 month later...

I got the resurfaced rockers and the cam back from DeltaCamshafts Friday.  The rockers looked really nice.  I bought them new, and the rocker pads had some very minor pitting which I didn't care for.  The same ones which I got back from DC looked much better than when new.  

 

I installed the cam today (put lots of assembly lube on) and fired the engine up.  A very different experience than the first time, when I couldn't get it to start, this time it fired right up and of course, had oil pressure immediately.  

 

I'll run it for a couple hundred miles and then take the valve cover off and have a look-see.  Can't do that though until I get the shortened Z31 T CV axles back from the Driveshaft Shop. 

 

G

Edited by inline6
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  • 4 weeks later...

Since I am waiting on the shortened Z31T axles, I went ahead and pulled the valve cover off to check the cam.  After not even 15 minutes of running at low rpm just sitting in the garage, the lobes are showing ominous signs...  In fact one of them has started ejecting its surface just like before.  At this point, I believe nitriding is the cause.  I read in a couple of places about nitriding cams causing the surface to be "too hard" or I guess having the surface made brittle.  So, the theory is that the impact, or perhaps the heating and cooling, or something else about this application, is causing the surface to "craze" or fracture and then fall off in tiny, tiny bits.  

 

So, the cam is trash.   :sour:  

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Why the nitriding anyways, if you dont mind the question? I have worked on many high performance engines and even some race cars, and 1 funny car. I have seen special coatings used on pistons, even the inside of the block, but never on the cam, ever.

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Why the nitriding anyways, if you dont mind the question? I have worked on many high performance engines and even some race cars, and 1 funny car. I have seen special coatings used on pistons, even the inside of the block, but never on the cam, ever.

The only reason I did it is at the time I was buying the cam (several years ago) was that there was a rash of discussions about the soft "cwc" blanks that it seemed every cam grinder was using.  I just thought that nitriding the cam would eliminate that issue.  Of course, the cam I ended up wasn't a cwc.  

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The only reason I did it is at the time I was buying the cam (several years ago) was that there was a rash of discussions about the soft "cwc" blanks that it seemed every cam grinder was using.  I just thought that nitriding the cam would eliminate that issue.  Of course, the cam I ended up wasn't a cwc.  

My 2 cents suggestion is call Delta cam. They can get you the cam grind you want :wink: I did and I am very satisfied. I called, we talked and by the time I drove down to the shop, my cam and rockers were on the counter waiting for me!!! Awesome people, awesome service!! And no cwc blanks are used...

Edited by 280zex
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