Camshaft help needed

[Jeff G 78]

First a little background...

I bought a Web Racing #91 grind camshaft about 15 years ago for my '78. I installed it and it ran like crap. After some research, I learned that the stock EFI doesn't like aftermarket cams, so I pulled the cam, springs, rockers, etc. out and stored them. Jump ahead many years and I decided to install the Web cam in my L26 race car with SU's. I did that in 2011 and ran a 25.5 hour long endurance race with the engine. The cam did great and it pulled to 7k, but the engine was just not making enough power, so this winter I bought an F54 engine and began my build. I pulled the Web cam and corresponding hardware out of my L26 and started assembling my P79 head today.

This is where the problem arises. As I was looking at the front end of the head, I looked down the barrel of the cam and I saw light at the end of the tunnel. I knew this wasn't normal as the internally oiled cam must be closed at both ends to force the oil out the lobe holes. I walked around my workbench to the back of the head and there was no plug in the end of my cam. Just a tapered hole leading to threads where a plug would go. My first thought was that the plug must have worked its way out right at the end of my last race, but after closed inspection, there is no way the plug could back out as it would hit the cam cover before the threads disengaged. There was no witness marks of the cam cover and no plug anywhere to be found. The cam lobes and rockers look perfect with zero signs of oil starvation or wear.

One of two things happened. A, the cam never had the plug an I have been really lucky that enough oiled drooled out the lobe holes to keep things lubricated, or B, the plug was just about to fall out when I removed the cam from the L26 an somewhere between the engine and the workbench, the plug fell on the floor. I haven't found a thing on the floor and I even went to far as to pull the oil pan on my L26 to look for the plug or any signs of metal shavings. The oil had absolutely no debris or signs of starvation. I just don't see either of these scenarios happening.

Does anybody have a Web Racing cam that they could inspect and tell me what the plug even looks like? I'm guessing that it's an allen head plug with a tapered head to seal against the cam.

Is there any way my engine could survive 25+ hours of race conditions with no end plug? This is the best pic I could get. The lighting was never right to get a clear picture of the bore and threads.

[madkaw]

Are you sure you weren't running the spray bar on that L26?

It's a simple pipe thread plug that you can buy at any hardware store. My Schneider cam has a Allen head plug.

I can tell you from watching this in action, there's no way that cam would have lasted without that plug. You have lost, misplaced the plug or ran a spray bar

[Jeff G 78]

Nope, no spray bar Steve. When I installed the Web cam into my L26 in 2011, I removed the spray bar and added the spray bar block off plates to the towers. Even if I was using the spray bar, the problem would be the same. No pressure would ever build in the drilled cam with the plug missing. I have spent hours tonight trying to come up with a logical solution and I'm drawing a complete blank. There is no way the plug could have come out while the cam was running in the car because there simply isn't space between the end of the cam and the cam cover for it to back out all the way. I measured the cam to cover distance at around 1/4" and the plug would have to be deeper than that. Had it backed out far enough to be loose, it would have rubbed on the cover and there are no witness marks on the cam cover. As for me losing the plug, I can't come up with any way that happened either. I pulled the cam out of the L26 which was out of the car and sitting on the garage floor and I carried it 5 feet to the workbench where I later noticed the missing plug. There is virtually no way for it to fall out in that time frame and I would have heard it hit an found it on the garage floor if it had.

As for the plug, I'm not sure the CMC billet Web camshaft uses a pipe thread. It is threaded in close to 1.5" and it does not appear to be a tapered thread. If it is, that will make life easy, but it sure doesn't look like a pipe thread to me.

I'm stumped... I agree that it should have chewed itself to pieces running without the plug and yet everything looks perfect. Maybe VR-1 oil is just that good?

[beermanpete]

What size is the thread? A 1/8 NPT socket head pipe plug is about 0.3" long. The threads in your photo seem too clean to have been run much without a plug installed. Did you clean them already?

Edited June 23, 2013 by beermanpete

[Jeff G 78]

Pete, I did not clean it before taking thee pic and I can't tell what the thread is since they start about .3" deep in the hole. When I insert my thread pitch gauge, it is too hard to see the results due to the depth of the hole. I tried my tap and die set and none fit, but it was somewhere around 1/2". The minor diameter measured about .4" with my calipers.

I will try a 1/4" NPT plug today after a hardware store run. I only have 3/8" NPT and larger plugs at home and all were too big.

[madkaw]

http://www.classiczcars.com/forums/engine-drivetrain-s30/23392-cam-oiling-investigation.html

I can't believe I almost forgot about this. The first post I did eludes to your situation. So maybe it's possible you ran it like that.

[beermanpete]

Pete, I did not clean it before taking thee pic and I can't tell what the thread is since they start about .3" deep in the hole. When I insert my thread pitch gauge, it is too hard to see the results due to the depth of the hole. I tried my tap and die set and none fit, but it was somewhere around 1/2". The minor diameter measured about .4" with my calipers.

I will try a 1/4" NPT plug today after a hardware store run. I only have 3/8" NPT and larger plugs at home and all were too big.

Try 1/8 NPT. The pitch diameter at the beginning of the internal thread is 0.373 and is the closest to your measurement. 1/4" NPT is 0.491 at the same point.

[Jeff G 78]

Thanks everybody. Steve had it right with 1/4" NPT. I found a plug at Napa and installed it with red Loctite. After looking at the plug, it must have never been there. There is no way it could have come out and not been stopped by the cam cover.

[LeonV]

How do your rockers look?

[Jeff G 78]

Leon, the rockers and cam lobes look perfect. There are no signs of any starvation.

[LeonV]

Leon, the rockers and cam lobes look perfect. There are no signs of any starvation.

Well either the plug evaporated or your valve-train's wear surfaces are very high quality and well matched!

[siteunseen]

Well either the plug evaporated or your valve-train's wear surfaces are very high quality and well matched!

Please update us with that motor. I can hardly wait to see what you say about it. I've read up on that cam and it looks good to my unknowing eyes. I have an E31 without the cam and rockers but the larger valves and an F54 with dished pistons. I hope I could make a decent running spare motor with what I have plus the cam kit.