Found the Problem!!!

[Vette79]

What's wrong with this Picture??? hnoes Took her out for a cruise and decided to open her up and then a noise, lack of power and running/idling rough. Limped home and let her sit for a couple of weeks. After working most of the week on installing new center cluster trim and center console trim and related pieces/parts, we finally got around to troubleshooting it. We started with removal of the plugs and found a light coat of oil on #1 spark plug. We were able to get spark at all cylinders. We were going to do a leak down check, removed the drivers side valve cover and "Whoaahhh". Broken rocker arm stud. The rocker arm had a bluish tint which means it obviously got very hot which led to the stud being stressed and snapping.
In any case, we removed all of the rockers and rocker studs. We are upgrading to 1.6 roller rockers and big block rocker studs. The pushrods are fine. Guess what I'm getting for Christmas???

 

[Copdogcorvettes]

You're lucky it didn't breck anything else;or did it? If you are changing rockers and the old ones are still good; I've been wanting a set!!

Good luck on the change over, You're going to like it when it's done.

Gary
Save the Wave

 

[Vette79]

We can talk, your welcome to them. Nothing else that we can tell was damaged. Just want to know why this happened?

 

[fine69]

Yep Jeff... I had the exact same thing happen to me... I believe it's on my online web album somewhere... Personally, I didn't like the roller tips (I thought I had written that to you..???).

I'm glad there was no damage to your engine.

I went back with regular style - but heavy duty rocker arms. I don't feel I've lost anything from not using the fancy rockers. My engine is pretty robust and I've stood on it a few times... all has been okay.

Ralph

 

[Vette79]

Ralph, I'm not so sure we discussed that but I can tell you that I'm not convinced it was an issue with the roller tip rockers. There has to be a reason why there was so much heat at that #1 intake rocker. Maybe it was to tight on the stud? Maybe there is something of more concern with the heads? Maybe it began with the motor being way to retarded during initial break-in after top-end rebuild and it just took this long for the stud to finally fail? No matter, vette is already up for the winter and nothing but time for research...lol.

 

[Evolution1980]

Maybe it began with the motor being way to retarded...

Man, I hate it when my motor gets all retarded on me. :Silly
I'm like, "What the hell was that all about?!?!?" :L

 

[Vette79]

Thank you, EVO......LOL.

 

[minifridge1138]

Man, I hate it when my motor gets all retarded on me. :Silly
I'm like, "What the hell was that all about?!?!?" :L

lol, that was great

 

[Bill75]

Are you sure the underside of your rocker isn't coming in contact with the top of the valve spring retainer? There's a line in the photo at 5:00......... maybe just a reflection. I know it's in the wrong position now but it could have turned during the mishap.

 

[Vette79]

Are you sure the underside of your rocker isn't coming in contact with the top of the valve spring retainer? There's a line in the photo at 5:00......... maybe just a reflection. I know it's in the wrong position now but it could have turned during the mishap.

Sorry Bill. That's just the flourescent shop lights. Three possibilities for this one that I can think of.

1. Maunfacuring defect. It happens.
2. Rocker nut to tight?
3. No or little oil to lubricate hence getting to hot causing the bluish tint we saw on the rocker and ball. Rocker stud snapped under stress and heat.

For sure we are getting full 1.6 roller rockers and BB rocker studs. Still would like to know why it snapped. We will check to make sure oil is flowing smoothly once we put it back together.

 

[Hib Halverson]

A broken rocker like that is not going to happen unlesss:
1) The engine has been abused
2) defective part
3) wrong rocker arm--slot not long enough.
4) problems with valve float

First thing you need to do is replace all the studs. Going to a "big block" stud is not necessary unless 1) you have high valve spring pressure or 2) the rpm band of this engine is such that it will see extended periods above 6500 rpm.

Next, deep six the stamped, roller tip rockers. In a practical sense they offer no performance or durability improvement--other than a ratio change if they were ordered as 1.6's. In fact, because of the roller tip, which is just a marketing feature, they sometimes are less durable than OE parts and have more mass at the tip. Neither features are good for performance but man, the aftermarket cam companies sell a lot of them because people think the roller tip is a performance feature.

Now, the best rocker arm choice is a real roller, rocker with a 1.6 ratio and I suggest the Crane Gold Race Rocker. I think they are the best choice for performance, reliability durability and price. There are cheaper die cast rockers, but I don't think they are as durable. There are more expensive stainless steel rockers, but I don't think the high price is necessary in this case.

Once you go to 1.6s, if you are retaining the existing camshaft, you need to make sure you have the right valve spring for the higher ratio as the rpm at which the valvetrain becomes unstable goes down as the rocker ratio goes up.

Lastly, if this engine uses a flat tappet camshaft, you need to make sure the engine oil you use as at least 1000 ppm phosphorous content.

Good luck.

 

[Vette79]

Hib, a rocker nut being to tight or no lubrication at that rocker will cause this failure. As for your list, the engine is not being abused, the part could be defective but explain the bluish tint, it is not the wrong rocker arm and there are no problems with valve float. As for replacing the rocker studs with BB studs seems to me to be the right thing to do as we should replace all the studs anyhow AND we are replacing the studs anyhow so why not upgrade for drivetrain stability? Also, we have been meeting the requirements for phosphorous content.