Dropped a valve...

Pulled all spark plugs, #4 cylinder plug was beaten, pulled the valve cover

Nice new invention, a valve that turns 90 degrees? Great for the flow...

Piston took some beating too

Look at the valve stem lock area, it's totally worn on the broken valve.

Status:
Need new piston, connection rod bearings, two valves, locks that fit for all valves, new rocker arm. Plus gaskets, fluid etc.

Only good news is that block and crank look unaffected. I'm trying to get it all solved so I can drive to Spa trip next weekend, so I hope MME are fast in responding. I'll keep you updated.

Ai, ai, no good at all. Hopefully you get things fixed in time, so you can make the trip, and enjoy the event as you had in mind.

May da force be with you!

You are very lucky if you haven't done damage to the cylinder. I've been down that road and the cylinder was trashed. But then I was at the end of a long straight at 5500+ RPM.

Good Luck.
Mark

Thanks Kid and Mark

The engine is still in the car, so now I know that you can do most things to your engine while in the car. But I envy the GT40 guys where the whole back end flips up.

That's rough, condolences.

-G

Mikael,

So sorry to hear of your engine trouble. Glad (and I hope it is the case) that the block and crank are in good shape. Even the ease of removing the rear clip on a GT40 doesn't make this kind of thing much easier to take. Good luck with the repairs!

Mark

Visited a few machine shops this morning. Different views, some think that the valve locks are OK, and that the broken valve is from rpm++. I shift at 6000, occasionally 6500.

Will call MME shortly...

The local parts guys I normally use can handle stock engines, but not this. When I explained the guy what happened and handed him the exhaust valve to see if he could find a replacement, he asked "Is this the intake or the exhaust valve?"

Damn! Sorry to hear. That's the second MME motor that I've heard that had catastrofic valve train issues. Chris Lewis had a similar issue.
Will

I've read that post and that was my initial thought that maybe this was the same. The machinists I visited today however said that it's been overrevved, he could feel at the back of the other valves that they had bounced.

I don't know, I want to get it running now, and winter time I'll take it apart and refresh it. With an agressive cam and 1.73 rockers, it'll never be a high rpm screamer IMO.

I previously had a long discussion with my engine rebuilder on rev limits, he bases it on max piston speed, so strokers naturally do not rev as high, you are relying on the higher torque (which is what you want anyway).

For a heavy duty engine with forged crank & pistons 4,000 feet per minute piston speed is the recommended max; for a 408 that equates to 6,000 rpm rev limit. This somewhat subject to valvetrain components being equally capable, but a good rule of thumb IMO.

Julian

I would suggest stainless roller rockers next time. Just a bit heavier but so much stronger.

Something doesnt look right ? It looks like the roller in the rocker failed first and the rocker road on the spring keeper and wore the top of the valve ? Then the locks popped out and the valve dropped ... Or maybe like the other MOTOR the valve springs were too heavy ?

Ron

You are correct Ron.

The rocker arm failed (the roller broke off) first, not the valve. This allowed the end of rocker to straddle the valve tip and push down on the spring retainer. Pushing down on the retainer allowed the keepers to loosen, fall out of the groove and fall off the valve stem. Once the keepers let go of the valve, the valve dropped. The piston hit the valve & broke the head off.

Look at the bottom of the rocker & the top of the spring retainer, it is evident they were in contact with each other.

The question is, why did the rocker arm break?

-G

Stainless roller rockers may be in the plans for this winter. Trade a little power for longevity might be a good idea.

Is the consensus for a 408 stroker max 6000 rpm? Earlier performance engines I've had lost a little power at 5500 so it was natural to switch gear. But this one feels strong all the way, so it's tempting to overrev. Maybe a rev limiter for my ICE ignition...

Thanks for all the suggestions, I'll try to deal with them all to avoid it.

I hate it for ya mikael.. My 408 has ss steel rockers. It pulls hard all the way to 6200, Then I put in a 6800 chip. I have not hit it yet. I was thinking about a 7000 limit... but NOW, maybe 6800 is enough. Coil bind could put a lot of stress on the rocker. That is why the behive springs allow more compession of the spring as the center area of the spring is larger diameter than the top and bottom areas.

Parts are on their way via FedEx from MME now. And the local machinist has promised me the head back by Friday. So in theory I should be driving by Sunday, but I know that if I miss one little $1 item, it wont run...

THat's great news Mikael! If you do make it in your Pantera, you are going to be the happiest, most satisfied person there (and that isn't to say that there will be happy people there!)

Good luck!

First, sorry for the grief but what I see is that is a two piece valve and it broke at the proverbial failure spot for the stock valves.
I'm not taking shots at MME here at all, just stating what I see.
If this is so, i.e., they are the two piece "avoid at all costs valves" then you need to decide if the heads should be pulled and all the valves replaced.
Second, if this is a hydraulic roller lifter camshaft, , that right there is part of the problem.
I suspect what happens is that even though that profile is "represented" as "streetable", it has a timing pattern that is not cushioning the closing of the valves. Most likely that is why the other valves are showing signs of "over reving".
If you search on this forum you will find another thread very, very similar in results to this with MME as the builder with mileage showing much less then yours.
If this is all a result of parts selection by the builder, then I personally would have to consider that as much more then an oversight or a coincidence. Particularly when there are two engines here in the same broken condition.
My personal opinion is that you just can't build these engines with components like AFTERMARKET roller camshafts and expect them to have a longevity significantly longer then an engine built to run in Pro Stock drag racing.
With 4,500 miles on it, the way I see it, that's 9,000 runs down the 1/4 mile...allowing for the return trip.
That thing needs to be serviced maybe after every run and certainly every 10 runs.
It is the nature of the beast that "you" have spec'ed and had built. It is a race engine no matter how you cut it and is going to have a failure, and service rate of one.
That really takes the builder off of the hook here. YOU have to know what YOU are spec'ing here.
The builder can only help make selections based on that criteria.

Thanks PanteraDoug
Let me just say I didn't spec the engine, I bought the car with the engine in it. As far as I know the previous owner bought a finished package, he didn't want something different/crazy.
MME engine
I want to use this car to drive across Europe, that may require different cam and valve train. That's this winter's project...

quote:

If this is so, i.e., they are the two piece "avoid at all costs valves" then you need to decide if the heads should be pulled and all the valves replaced.

It's my impression that the parts in the engine are not cheap, like Scat rods and Probe pistons. But I don't know about the valves. They're marked:
REV CL 1660
REV CL 1614

Can't find them at Summit. Are they the "avoid" valves?!

Working on it...REV, that is. I have a contact that sells valves directly on Ebay. These may be his. Shot him an email. If they aren't his, he will know who REV is, sounds familiar but can't place him. Will get back to you as soon as I know more.

Are these stems cut down smaller then 11/32" at the stem for "greater flow"? Can't see that clearly in the picture.

They would only be an "avoid" item IF they are know to be two piece construction. Sometimes because the stems are polished into the tulip of the head, the seam is no longer visible.

Even Ferria no longer makes their own valves. They are largely all made out side of the US. Some come from Mexico, South Africa, or Israel.

Companies buy then and put their own brand name stamps on them. SS valves are all price competitive now and US labor rates would make them non-competitive on the market.

Crankshafts and connecting rods are largely being cast or forged in China. Machining done in the US.

Quality control has to be done by the machinist here. They are all US designs and absolutely nothing wrong with the design.

Scat is not a cheap product. Neither is Eagle.

They're 11/32 all the way.

Here's a link to the REV CL 1660

and here's link to the REV CL 1614

I don't post much on here, but I'm particularly interested in this thread since I'm building a 393C as we speak. I'm curious if you know what your spring pressures are? Sorry about your trouble.

Thanks,

Chance Dorsey

I presume that Chevy valves were used because these are after market heads using Chevy dimensions?
Look at the stem detail in the pictures. Those are cut down stems for greater flow.

That isn't anything that has proven to be a problem in either case though. I use +.100 length Chevy valves in SB Fords (289/302)WITH the cut down stems and they work great. Ford valves are a little short a lot of times and the +.100" length works better.

I guess if you are going to kiss a piston with a valve, the weakest point is going to break. Usually you will bend a push rod, but if the valve gets sucked in something else needs to break?

Still working on the source of the Revs. I think those are the Argentinian ones? same as Farrea.

Regardless of all of this, you still need to find out why the other valves are showing signs of abuse.

Again. I would look at the camshaft profile.

OK. Just heard back from Ted, my valve expert. Here is the direct quote:


"Morning!

Our part number is 11800EPN and 11803EPN, those numbers you mention are Rev products. Rev supplies (or at least used to) an India made piece, produced by Vikram. They don't make valves, they just import them.

Two piece valves are joined in the middle of the stem, not at the head of course so that wasn't the problem.

OK for stock use but not performance, we looked at the brand line but rejected them long ago.

Note the slight bend at the end of the stem, that is classic from an impact. If the head of the valve just fails and comes loose, this almost never happens, so the valve likely bent from hitting a piston first. Usually a good valve will make many many hits before snapping like that, this one let go in just a few bumps.

Plus look at the stem, signs of burnishing? Then the rocker arm roller is gone?

The valve stopped moving, the rest kept going. You might even break one of mine when this happens, pretty severe damage there.

I won't install a Rev valve myself.
Ted"

He's also a retired race engine builder. Lot of experience there...and good judgement.

Hope this helps. Sounds like someone needs to verify piston to valve clearances with clay?

More from Ted Standwood on the subjuect:

"There is no seam just under the head of any valves, the process of friction welding would make that very nearly impossible to join at that point.

This is partially due to the shape of the head of the valve, it would require a very serious and complicated setup to spin the valve head against the stem which is part of the two piece process. Then due to the various head sizes, it would take massive amounts of tooling to even set up.

Friction joins dissimilar metals, they actually fuse as the molecules flow into each other.

The reason valves always break under the head is this is where stresses occur, I have never seen a two piece valve ever break at the union since that is in the middle of the guide and actual measured loading at that point is really rather gentle.

There are almost no two piece valves produced in today's world, this is because modern equipment is much faster using the one piece product. Draw forging is so fast and accurate that performance valves have actually come down in price, it is the alloy used that is costly.

A typical stock alloy like HNV material is about 20% of the cost of EV8 grade alloy. Nearly ALL imports and many domestic OEM's use HNV material, then nitride over that which is a very cheap method, far cheaper than Chrome plating the stems which would otherwise be required.

So even import valves are all one piece now. There is still a plant in Argentina that produces industrial Diesel valves using the two piece method, that is the only one left that I know of. There are no USA valve producers left in operation. Even Manley and Ferrea have gone to Huaija Denyun in China, way the world is. We still use Eaton but it gets tougher every day for us.

Hope this helps,
Ted"

You can find him at engnbldr.com. As far as I am concerned, the Professor has just spoken and left the room. I always feel enlightened when he speaks.

Two possibilities. First, the keeper was chipped during assembly, resulting
in a loose fit that wore against the valve until the valve slipped out and
smacked by the piston. The resultant motion knocked the roller rocker tip
off. Second, the tip of roller rocker fell off but the rocker kept pushing
on the retainer until it wore enough for the valve to slip out. Not sure
which it was but neither of those implicate the valves.

> Second, if this is a hydraulic roller lifter camshaft, that right there is
> part of the problem. I suspect what happens is that even though that profile
> is "represented" as "streetable", it has a timing pattern that is not
> cushioning the closing of the valves.
>
> My personal opinion is that you just can't build these engines with
> components like AFTERMARKET roller camshafts and expect them to have a
> longevity significantly longer then an engine built to run in Pro Stock
> drag racing.

Hydraulic roller camshafts have lower seat accelerations than a performance
solid flat tappet and usually have a lower ramp rate. For instance, an
OEM flat tappet cam has a ramp rate of around 2. The hydraulic roller
I spec'd for Mike Drew's 408C is around 3 but the solid flat tappet cam
in Mid Engine Mike McDougal's 393C is right at 5. I don't know what lobes
MME uses but a hydraulic roller with a very large ramp rate would not
rev well in an engine like a Cleveland (large rocker ratio and heavy valves).
One issue rollers can have is if the springs have insufficient seat pressure,
the valves can bounce off the seat. Solid rollers are a completely different
animal. Some of those can be quite aggressive but there are also more gentle
street lobes available.

> Most likely that is why the other valves are showing signs of "over reving".

Do the other valves show a wear pattern like the failed valve?

The big question is where is the debris from this mess. Did it find its way
to the bearings? I'd disassemble the engine and check all the bearings. If
you run it the way it is, you risk scoring the crank or a piece of debris
clogging a pushrod or oil passage which can lead to more catastrophic results.

Dan Jones

Once in a while, a builder in a hurry will use 7 degree stem locks in a 10 degree retainer, and vice-versa...

quote:

Do the other valves show a wear pattern like the failed valve?

The local machinist felt the backside of the valve head and made the statement that they had bounced. Haven't heard that before.

quote:

Once in a while, a builder in a hurry will use 7 degree stem locks in a 10 degree retainer, and vice-versa...

My son's school geometry ruler says 10 degrees on both.

Not to argue but what exactly is the purpose of using a roller camshaft if the profile is less radical then a solid lifter profile?
The point to ME is that you are going to gain torque in the engine by opening the valves at a faster rate then the lifter on a solid cam lobe can follow, i.e., it is a more radical cam profile.
Part of the purpose of greater valve spring pressure is not only to control the additional mass of the additional valve train components but to make sure that the valve is put down on its seat without bouncing off of it. That is made necessary by the more radical timing, i.e., the rate at which you are decelerating the valve?

If you are telling me that you are installing a roller cam for the purpose of dealing with less ZDDT in the oil, then that is mighty green of you and in my opinion kind of ridiculous too considering that you only have a valve train that will rev to 6500 rpm or so?

In addition you are increasing the possibility of catastrophic failure in the valve train exponentially because of additional components.

You have a cam of lower performance potential of a solid lifter cam. I thought the point was to solve the problem the simplest way, not the most complicated way? Hum? Excuse me. Must be me?

Well that head has to come off to fix the valve. If your local machinist is correct and the valves have been floated, there should be some pretty obvious marks on the pistons.

If that is so and it was me I'd be asking myself some pretty serious questions such as why can't the valve springs, the locks and the retainers control the movements of the valves precisely without failure in routine operations? Is it worth the risk of constant valve train failure just to be able to say "I'm runnin' a roller cam?"

Like I said, after market roller camshafts and valve train are going to require much more maintenance and should be treated as a "race" prepped engine. That is what the derive from and that is the durability that they will exhibit.

My guess right now is that the rocker broke. And what do I base that on? The way the metal hitting metal sound behaved when I became aware of something was wrong. It was on and of. If the valve head broke off, it would be constant? And if the locks didn't work I think it would be constant. But if the rocker broke first, it would still lower the valve somewhat (see first picture), and as the locks wore down the groove on the valve stem the valve could go further and further down.

Well maybe.

Another interesting thing that leads me to this theory is that the the rocker while looking similar and having the same pat nr on it, it doesn't have comp cams stamped on it. Chinese crap? Or at least diffent batch?

Of course the problem whatever it was was multiplied by a highlift cam and 1.73 rockers.

> The point to ME is that you are going to gain torque in the engine by
> opening the valves at a faster rate then the lifter on a solid cam lobe
> can follow, i.e., it is a more radical cam profile.

There is acceleration and there is velocity. The two are separate concepts.
A flat tappet cam can accelerate faster off the seat but a roller can achieve
higher velocity. If you set up a cam on blocks or centers and use a lifter
jig or plot it out on paper, it quickly becomes apparent that the range of
actual lobe profiles is limited. For flat tappet cams, the diameter of the
lifter or the length and curvature of the finger follower defines the limits
of possible profiles. Once your pressure line gets to the edge of the
follower, there's no more to be had. For rollers, the diameter of the roller
is your limiting factor. Eventually the pressure line reaches the height of
the axle, and spits the roller off to the side. In practice, there is a
duration point below which a flat tappet will make more power and above which
a roller will make more power. Also, large port engines (like 351C-4V and
429/460 BBF) do not respond well to high acceleration rates.

> If you are telling me that you are installing a roller cam for the purpose
> of dealing with less ZDDT in the oil, then that is mighty green of you and
> in my opinion kind of ridiculous too considering that you only have a valve
> train that will rev to 6500 rpm or so?

That's why many engine builders go to rollers. Too many flat tappet cam
failures. Added power can also be a bonus. For a flat tappet cam to
make the power of a similar roller, it is going to wear at a rate that
may be unacceptable. For a flat tappet, wear is pretty much a function
of load at the pressure line. The more aggressive the flat tappet lobe,
the higher the spring pressure and the faster it wears. That's why the
OEM cams have such a low ramp rate. They had to last 100,000 miles back
when oil had a lot of ZDDP. For hydraulic rollers, oil viscosity and
pressure are your main limits, where leakdown starts to change the valve
motion significantly from the lobe motion. For a performance flat tappet
cam, longevity is sacrificed first. You can load the cam more heavily,
and shorten the ramps to make power but the candle that burns twice as
brightly burns half as long. A hydraulic roller cam can make very good
power and last much longer. Solid rollers have their own set of problems
(oiling at idle, valve lash pounding the tiny needle bearings). Power is
cheap. Longevity is not.

> In addition you are increasing the possibility of catastrophic failure in
> the valve train exponentially because of additional components.

You keep confusing hydraulic and solid rollers. Hydraulic rollers have
been used for decades in OEM applications and have proven very reliable.

> Hum? Excuse me. Must be me?

Apparently so.

> Well that head has to come off to fix the valve. If your local machinist
> is correct and the valves have been floated, there should be some pretty
> obvious marks on the pistons.

Floated valves don't necessarily hit the pistons. He also mentioned bounce
which is not float.

> Like I said, after market roller camshafts and valve train are going to
> require much more maintenance and should be treated as a "race" prepped
> engine.

Then why is it I have more than 220,000 miles on a roller cam (stiff springs
and 1.7:1 rocker ratio) that shows no wear?

Dan Jones

Overall ... I see a pattern .. rocker arm failures too high spring pressures ... check the valve spring pressure recommended by the manufacturer of the cam and to rocker arms and compare to whats installed. If thats all fine then I would say human error with the wrongkeeper etc. Remember there is only a few here who need motor jsut for 5000 miles the rest of us who like 75k miles on a motor so Solid roller cams , high spring pressures, on the street are all short term engines.

The old 5.0 Mustangs of the late 80's and 90's all had OEM roller cams. I owned one of those and loved it. The motor didn't burn much oil at 180k miles and still ran like the day I bought it. But that's just my experience, and that roller cam wasn't a high-lift cam.

Dan, what about ramp rates and side-loading of the roller lifter with steep rates?

The cam is MME's proprietary cam, specs unknown...

Status
-Left head assembled and mounted
-Right head said to be finished machining in an hour, driving to pick it up now
-Parts from MME via FedEx didn't come today as promised, FedEx blames strike in Paris (having worked in Paris, that sounds very likely). So maybe(!) I'll get it Friday.