Valvolean

[LoBelly]

So the car was running great just before the Nationals

but lost power after only a couple of laps

When back in the pits I prepared for a restarted to see if I could diagnose and few of my team-mates gathered to lend a hand - there was a god awful racket.


Rocker cover off - this is what the valve train looked like

hmmm... one of those is a little high...



I am done for the weekend

Back at home the disassembly starts...





text and more images to come - trying to get all the images organised

[MikeFromPerth]

You know what I mean

[Gaz64]

Unfortunately, I would say that is engine out now.

Gary

[Aussie Mike]

Michael, Can you get the heads off with the motor in place?

Cheers

[boxhead]

Any idea as to the root cause?
To my eye and from camera angles, it looks like the rocker arms are very close to spring retainer?
Are your pushrods maybe a touch too short?

[albanycobra]

Did the engine get a big rev? Maybe a valve touched a piston?

[Gaz64]

Originally Posted by boxhead

Any idea as to the root cause?
To my eye and from camera angles, it looks like the rocker arms are very close to spring retainer?
Are your pushrods maybe a touch too short?

That is a good point, were all the rocker clearances checked? Rocker to retainer, rocker to stud etc?

The pozilock screw seems to "out" too much, indicating pushrod length too short.

Originally Posted by albanycobra

Did the engine get a big rev? Maybe a valve touched a piston?

That could be the case, but if that happens the valve stem in the guide should still be intact.

In the photo, it looks like the valvestem must be bent at the top of the guide.

Gary

[albanycobra]

I agree the posi's are high, mine are bout 5 or 6mm down.

[Rog246]

Originally Posted by boxhead

Any idea as to the root cause?
To my eye and from camera angles, it looks like the rocker arms are very close to spring retainer?
Are your pushrods maybe a touch too short?

Push rod............what's a push rod !??!

Oh sorry, just realised its one of them Chevvy ARK thingies

Okay I've thrown the burley out...........who's gunna bite ???

[Dimis]

Oh dear... That don't look right.
Im a little bummed to see that Lobelly.

Just so I'm not misunderstanding. Are you suspecting valvoline is part the cause for your valve-o-lean?

To my inexperienced eyes it looks like something may not have been quite right (either with the metallurgy, or part, or build,) rather than oil supply?
I'm happy to be corrected and educated.

Good luck with IDing the cause and the fix.

[Aussie Mike]

Originally Posted by Rog246

Push rod............what's a push rod !??!

Oh sorry, just realised its one of them Chevvy ARK thingies

Okay I've thrown the burley out...........who's gunna bite ???

You've thrown the burley all over yourself. It's a Ford Windsor motor LOL

[Aussie Mike]

It looks to me like the head has broken off the valve. I suspect when you open it up you will find it has pounded itself into the combustion chamber and the top of the piston.

[750hp]

You've probably got it all apart now, so everyone diagnosing/guessing the issue is just our little challenge based on your unfortunate experience.

That said, I agree with Mike. A godawful racket and the valve sitting like that usually means the valve head has been dancing around...and that's never pretty.

[LoBelly]

What observant folks you are - and perceptive

I mentioned earlier that a number of my Vic team-mates came to offer a hand / sympathise or see if they could otherwise help.

Before the valve cover came off Ben (Modena) had his multi-meter out and determined that the fuel pump was not getting 12v.

After the raised rocker was found the working theory was that a lean condition may have let to the valve failing, turns out this wasn't the case though.

And Yes the head of the valve had lost its head...



and at some point had decided to say hi to Mr. Piston



After some light petting Mr Piston appears to have forcefully rejected the advances (thankfully) and the valve has lodged in the head - definitely not moving.



To be honest I was quite relieved with what I had found.

[LoBelly]

So the next question became "What to do with the heads?"

I looked for a local head specialist (not really expecting to find one) but discovered ...



Who - in their Historic Cars Section cite another of the my Vic team-mates who was very helpful on the day Trevor Simkin. Small world - Trevor also did the dyno run in on my engine, so I ring Trevor who tells me that the owner Eddie Woods is a top guy and does fantastic work - great

this is Trevor doing the run in on the engine in November 2007.


A couple of days later I drop the heads at HSD. The factory has a great feel and they've a mix of old and new stuff about the place.

Picture is a bit blurry but you get the idea...


While I'm there Eddie looks over the heads and says the head snapping off the valve is often indicative of valve bounce (I'm paraphrasing).

I also send Eddie the photos and he also thinks the rockers are a bit high and the push-rods might be to short. But also notes that the wipe area on the valves looks fine - speculates that there may have been some interference with the valve and stresses the importance of the rocker in the middle of its range at mid lift.

I get a quote for the head work and - what seems a short while later - get the heads back (came in $300 under quote )



Looks like new

HSD have cleaned everything up nicely


And done a little port work for me ...'just to tidy things up - they'll now flow better'




While I was picking up the heads Eddie made me a push-rod measurer to loan and also provided a light spring so I could check the push-rod length

[LoBelly]

So after my discussion with Eddie on the possible interference with the valve I start looking at the rockers

One is quite damaged - which is to be expected - it takes a while but eventually I notice some wear on some of the rockers.

It is actually quite hard to see unless you get the light right - I took a bunch of photos and you can only make out the wear in a few so I'm posting those.

not damaged



damaged - note the ridge where the tip roller slot ends.
a slight bevel has formed.


with the flash on you can see that almost half the rockers have formed this bevel.


I have a dual pattern cam and the intake lift is greater than the exhaust lift - so this would support the idea that the intake rockers may have been interfering with the spring cap and perhaps introducing a little side load.

Given the very slight nature of the wear it may be something that has developed recently.

A note on blame:
I feel compelled to try to cut off any criticism of the engine builder here.
I ordered the push-rods before the engine was assembled not realising that they should be specifically measured.
When I picked up the engine the push-rod length difficulty was pointed out to me and it that it was 'a lot of stuffing around to get them to clear' and that was over 8 years ago.
I could have done something about it in that time but let it go.

[albanycobra]

I set my pushrod length at 50% valve lift at cam and the rocker at 90deg to the push rod for a starting point.

[LoBelly]

Back to it

Assembly time

I am very focussed on getting the push-rod length and rocker install positioning correct - calculating the centre of the sweep and half the lift and mapping those points out on the rocker...


I use a marker on the valve tip to check the wear pattern - the spring is so light the marker hardly wears off.


Anyway - I end up with a measurement of 6.407 (which nobody makes as a push-rod length).

Eddie from HSD had suggested I use locals Crow Cams for the push-rods as they sell in 0.05" increments



I rang Crow Cams on the Monday before the Australia Day holiday sort of expecting they'd be closed.

The price for a set of Crow's push-rods was within $10 of Comp Cams Magnum range at Summit after the exchange rate but before shipping.

Crow shipped the push-rods that day and I had them by 4:00pm - I was impressed

[Aussie Mike]

Glad you got it sorted Michael. Is the piston OK?

Cheers

[LoBelly]

Originally Posted by albanycobra

I set my pushrod length at 50% valve lift at cam and the rocker at 90deg to the push rod for a starting point.

I think I must have been typing ... looks like we've both used the same

method.

LB