06Estukay

Guys,

I had a rocker arm roller fail on me a couple days ago. The cylinder head has Supertech valve springs and I was running BC Stage 2 cams. The cam got chewed up.

I replaced the cams with OEM AP1 cams, and replaced all the rockers for the affected valve pair with rockers I had from a spare head.

Upon closer inspection, I noticed a big score mark on the cam journal of the #1 (front) rocker holder.

Here's a picture of the score mark:



This full head assembly came from a mystery motor, and I had a local guy build it. So I'm not sure if the score mark was there when I bought it, or if it happened after my engine builder built it. Can't trust anyone I tell ya!

My question is, can I replace just that one rocker holder (and matching cap) with one from another head? Or, does it have to all be a matched set?

Cheers,
Alan

postman

Use a matched set. Otherwise you might be in same situation sooner than you hoped.

06Estukay

A matched set as in just a matched pair of holder and cap for that one position? Or a matched set as in all holders and caps from same factory head?

Slowcrash_101

Well think about it logically. The thing that is important when assembling is that the holders be paired with their caps, and that each holder and cap combo goes with the corresponding cylinder. So if you get a matching holder and cap for the matching cylinder you should be ok.

06Estukay

That was my first gut feeling, but the more I think about it, the more I feel I need to swap all holders and caps from the other head... wouldn't the entire holder / cap assembly be align honed from the factory to a specific head?

wadzii

that scar wont really hurt anything, just make sure its smooth, maybe hit with some scotch bright and let it go.

Typically rocker rollers break due to oil issues.. oil got too hot, too thin, etc.

06Estukay

Thank you kindly sir!

The engine oil is Amsoil racing 10w-30. It is a track car. It is running 12.5:1 compression. I have an oil cooler installed as well. Do you think the oil cooler is causing a pressure drop big enough to cause rocker failure?

Slowcrash_101

You can always check with a straightedge and feeler gauges. Wadzii knows his S so I would take his word over mine. Oil cooler wouldn't decrease oil pressure unless it was leaking, or had air in the lines.

wadzii

The cooler could cause problems. I have seen it before. I'd put a gauge on it and as far as the can towers.. I have replaced just one but I don't like to. They are line bored as a set.

Which valve springs do you have?? Double check for binding as well. Valve float or spring bind can also bust a roller. I have seen some heads that had signs of valve float busy rollers after we upgraded everything

06Estukay

Yeah, I've always been weary of oil coolers and their affect in the the oil system in regards to pressure and flow. But since it's a track car, I figure heat would be the worse of the two evils.

Ok, so I took your advice and cleaned the scar with a scotch brite pad. Cleaned it with varsol, then gave a good wipe down. Oiled up the journal and rocker bores before reinstalling. Confirmed with my local engine builder, and he recommended the same thing. Never split up a set of holders and caps.

I'm using Ferrea valves and keepers, supertech springs, retainers and seats. The springs are the 1020's. The website says 100 lb seat pressure, but the box was labelled as 95 lb pressure.

Now that I have the OEM cam back in, I want to swap all the springs and retainers back to OEM ap2 units. I don't think the stock cam needs anything stiffer, especially since I'm only running the car to 8500 rpm. Even if I go back to a BC2 cam in the future, the stock springs should handle it.

The thing is, the car hasn't even seen severe hot weather at the track this years. Only 2 days of track on this motor. Couldn't find any signs of burnt oil anywhere. So the roller failure is still a mystery. I do know the head came from a turbo motor that blew. Not sure if previous owner had put enough heat in the the oil to cause fatigue.

Thank you kindly for the help wadzii. Greatly appreciate it.