4000miles on these heads with Comp Magnum 1.6 Roller Tip Rockers, Comp XE 262 cam

I knew I had a valve not sealing because I found it on the leakdown test.

Took the Cast 200cc/64cc heads into the machine shop to get cleaned up and test with the vacuum gauge.

ALL exhaust valve guides are shot. TONS of play. The intake valves weren't too bad at all.

Shop thinks it's the 1.6 rockers.... but I've heard that the XE cams slam the exhaust shut, causing seat wear, but would it make the guide wear too?

Pushrod geometerty was perfect, varified by the sharpie on the stem tip.

My next cam will be one from Harold, Solid Tappet.

Do I go back to 1.5 rockers, or just attribute this failure to the cam or hardware in the head?

If you had access to a Sunnen guide mike, you could determine whether the guide is all over the place, tapered, out of round, etc. That would indicate wear. It the guide is straight and true (and they're all the same or close to it) but oversize, that might indicate a QC problem at time of manufacture. If the contact pattern of the rocker tip is centered across the the top of the stem, I don't think the rockers or pushrod length are your problem. Does your machine shop have one of these tools? They're expensive and require skill to calibrate abd use properly, not all shops have them.

Tom

I'll ask them. Not sure if they do. Each guide wasn't loose consistantly, infact one of the guides held the valve nice and tight. So it varied. I didn't check them when I got the heads as they came assembled.

In my experience, the pro-toplines have HUGE QC problems. I'll definately never buy another set.

Were the heads assembled by the manufacturer or a parts supply house?

Assembled from pro. The castings are beautiful!

But might be the machining wasn't so beautiful.

Twi,
What kind of shape were the valve stems in? In most cases, valve guide failure will also result in worn or galled stems. Also check to be sure that your springs are square. (Put them on a flat surface and check them with a machinist's square.) Doubt that springs are your problem though, since only the exhaust guides were affected.

may be a QC problem, half mine were way out on my out of the box Sportsman II's a couple years ago...major oil consumption and fouling...perfect after I had the factory ones drilled and replaced with bronze guides....

The stems looked fine to me, and the shop said they still looked good.

It had bronze guides which maybe the guy above was on to something with them being too large from the get go.


What about guide plates? Though the tip of the rocker was right atop the stem.

Make sure the geometry is not way off. It can put tremendous side loads on the guides.

I've got a picture of the felt tip results but for somereason I can't get cardomain to load up to host it.

So the machine shop went to work putting in the new guides and while they are at it they do a little bowl and chamber porting.

Finished one head, started on the other and found two cracks in the heads. Near the seat from the exhaust going towards the intake.

Nice. No wonder Protopline went out of business. graemlins/clonk.gif graemlins/clonk.gif graemlins/sad.gif

I may be out of line because I have nothing to base this on, but it could be the result of typical corporate greed - we've got a good product and a good reputation, people are buying, let's cut costs and make more money. Just a guess. Sorry your heads crapped out.

Shop says he THINKS he can fix them somehow with installing two new seats and doing a little more work on it. We'll see. If not I guess the car wont be going this summer while I save up for some fastburns.

Sounds dumb, but check your timing. If you were retarded it will take the ( exhaust)guides out. I had some severe issues with guides and found the timing was off, like 28 degrees all in. The guides on the exhaust ovaled themselves, the intakes looked 100% fine. The heat generated from bad timing stays up top in the exhaust head area. 1.6 rockers will not cause this to happen, but once the heated retarded exhaust guides start to wear, the 1.6 just puts additional load on an already overheated exhaust guide and valve stem.
Took all 8 bronze exhaust guides out and one intake, ovaled them like the blue oval hehehe, expensive, and not funny.
You could rock the stem at leat 1/4" at full extension and phisically see the oval.
Replace all the seals as well as we found even cooked they still held most of the oil out of the chamber.
By the way, were you pinging a lot?? My 10.2 compression motor just did not like to be a part time diesel engine, and the pinging is what stated the hunt. After changing the timing to 36 we still pinged like crazy. Taking the timing back to 28 we still pinged. By then I had beconme a deisel detonation engine, oil past the guides.

She never dieseled and I rarely recorded some knock. And since it was a knock sensor that retarded the timing for me up to 8deg, It was never audible knock.

I found myself to be off by about 4deg less than I should have at one time from a loose dizzy. Other than that timing was definatly in order.

More topline problems never seen more posts about them check perfomance history. lot's of info around the middle of March.