My Trans Am never ceases to amaze me on how it can break...

A little background info (I'll do a proper build thread later):

I've had my Trans Am since 2002. In the past 11 years, it's been through hell. The stock 403 was rebuilt once by me, but after it started leaking oil from the head mating surface where the block and the head meet, I got fed up and built a Pontiac 400 motor for the car. This was back in 2008. This motor has a Comp Cams Xtreme Energy 268H cam, .060-over forged pistons with file-fit rings, and nice Harland Sharp 1.65 roller rockers, among other things.

A couple summers ago, I finally got enough bugs worked out to start driving it regularly. It was really fun to blast around in even in its rusty, ratty condition. Last year, I fire it up for the first time in the spring, and it has a slight miss. Then it starts to blow blue smoke out the driver's side tail pipe. I pull all the plugs, and sure enough the #5 is oily. Also, the valvetrain was a little loud so I pulled the valve cover on the passenger side (because it was easier). Oil was having trouble getting to the top end.

Fast forward to yesterday, and I decided to pull the intake to see if maybe we put Chevy lifters in there when we rebuilt the motor (very common Pontiac engine builders mistake). I get the intake off and the valley pan, and this is what I see:

Not good. But how can that happen? This is how:

The rocker nut, even though it was set up just like all the others, somehow backed off and is gone. Just GONE!!! I'm hoping it ended up at the bottom of the oil pan. Good news is that the pushrod is fine and the rocker arm and stud are ok too. For now, I'd like to replace the nut and fire it up to see if it solves the issue. I plan on pulling the drivetrain from the car later on, so I can retrieve the nut later on. The motor runs fine other than the slight miss and the blue smoke, so it didn't do any mechanical damage.

Anyone know where I can find one of these specialty nuts?

http://www.summitracing.com/parts/tfs-70000904-1/overview/

Ouch. Good luck.

Interesting.... I seem to remember something from the dark recesses of my mind about burrs on the top of the stud keeping the set screw from properly locking in place....

But don't quote me on that... An I am glad nothing was damaged...

Scott

I've seen that happen before when the polylocks aren't tightened enough. I have had good luck setting the lash, tightening the nut, snuging the set screw, resetting the lash, and then tightening down the set screw good.

I think I found one...

http://www.amazon.com/Cams-4600-1-Hi-Tech-Rocker-Adjusting/dp/B001O062YI/ref=sr_1_2?ie=UTF8&qid=1364562726&sr=8-2&keywords=rocker+arm+adjusting+nut+7%2F16

The heads have been upgraded to ARP 7/16'' Big Block Chevy screw-in studs, so I think I found a winner.

Never seen that. I did once own a 318 Chrysler that had had two pushrods shoved THROUGH the stock rocker arms. Explained the dead miss.

Are you sure that crud in the valley of #5 is non metallic? I hope it's cork...

psteav wrote: Never seen that. I did once own a 318 Chrysler that had had two pushrods shoved THROUGH the stock rocker arms. Explained the dead miss.

My 73 Challenger did exactly this, and put on a hell of a smoke show in the process. But then that car broke in a lot of interesting ways.

Dashpot wrote: Are you sure that crud in the valley of #5 is non metallic? I hope it's cork...

It is cork. The valley pan gasket fell of in chunks on it's way off. The motor oil is gross though. After I get the new rocker nut in, I will be changing all the fluids immediately. The motor only has about 1300-1500 miles on it max, so it's still breaking itself in.

Well, that'd sure cause an oiling problem...

When I was selling race car parts way back when Harland Sharp said you had to be certain the tip of the stud was ground flat and square or the locknut could come off.

Curmudgeon wrote: When I was selling race car parts way back when Harland Sharp said you had to be certain the tip of the stud was ground flat and square or the locknut could come off.

Interesting.... I'll keep that in mind.

I ordered a new nut last night along with a valley pan gasket. Hopefully I can get this heap back into service for the summer. Driving the 3 every day is making me bored with it's reliability. I will be re-adjusting all the nuts just to be sure. They have been on there for about 500 miles, so it's probably a good idea anyway.