lash-caps Horror

[1950split]

Hi,

I wanted to adjust valve lash today and after removing the valve cover I found this small metal part in it. Looked at my rockers and lash caps and found that on cylinder 3 exhaust, the top of the lash caps was cut-off ..

Lash caps are from Gene Berg, rockers are the latest 1.4 from CB, cam is a CB 2289, springs cb 640 and 44x38 valves. Pushrods are tapered aluminum. The engine is a 2276.

How can this happen? Too tight valves? I set them at 0.15mm. The rockers are also worn and have a cut on on side that is the round external shape of the caps..

I guess I’ll to take the engine apart and start everything again..

Thanks for your input..

Phil

[Dan Ruddock]

Wow, must have been making a lot of valve noise with it like that. I like to setup my valve train to be as quiet as possible so if something goes wrong I can hear and correct it right away. With a noisy valve train all the noise starts to coverup a problem. I am also not a fan of the Berg tight fitting lash caps but do like most of his parts. What caused your problem? not sure. Is this a race or street car? A loud open exhaust will also mask a problem.

Dan

[Chickensoup]

Lack of lubrication? Just throwing out ideas.
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[nsracing]

I am surprised it did not jump out and destroyed the motor.

You could not hear all that clatter?

[mark tucker]

rong geo, junk lashcap, interfearance like lash cap was contacting the retainer or the keepers. do not just put another on it find out witch it was!!! probably cap to keeper/retainer interfearance. or a junk cap Ive seen many they were not machined worth a shit on the inside floor/roof and some that were not flat on top they were domed. if your rockers are too high they will walk off the edge and can do this as well as kill the valve guide. also check pushrod for dammage. and yes a rocker thats not square to the valve stem can also do this or one that had a hard burr or sharp edge.

[mark tucker]

how could you 1 not hear this? 2 not feel this?

[bugguy1967]

Seems like the heat treat was not done properly, or the rocker pad was not parallel to the cap, causing uneven wear. Also, unless you’re lifting over .600” and revving over 7,5K, why the .650s?
_________________
"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[GARRICK.CLARK]

Looks like the valve keepers on that bad exhaust valve were not clamping tight on the valve stem, you might need a new exhaust valve, valve keepers need to be not touching each other when fitted to a valve stem. Clearance them all so they don't touch.

[Ohio Tom]

Gene Berg.. Only the best..

[UK Luke 72]

[FreeBug]

Those things are pretty tight fitting. Could it be that it wasn't fully seated, leaving a gap above the valve stem?

My issue with that setup, is that there is no valve rotation. The caps being so tight has nothing to do with the valve not rotating, to the contrary, if the rocker-cap geometry causes rotation of the valve, the tight cap would help.

The issue that prevents rotation is the claeranced keepers and valve stem. I wonder if CB's valve/keeper allows rotation?

Having said that, here are thousands of those being run with no issues. Why the Berg bashing? If you think it's pricey, you don't have to buy it, right?

[1950split]

Hi,

Thanks for your replies.

The keepers were sanded in order not to touch each other and the caps were not tight on the valves. They were not touching the keepers. On the same cylinder side, 2 lash caps are fine and the rockers don’t show bad wearing , one got cut-off and the other is concave.

What springs could I use with the CB 2289 cam and 1.4 rockers that are not so harsh on the distribution? Beehives could be nice but the OD of the spring is smaller than CB650’ so unless I get my heads welded I cannot use them. Any other option?

Why the CB650 springs? Because originally the car was supposed to do some drag racing when the engine was first assembled but it I am not racing anymore.

[Dan Ruddock]

[1950split]

I get as a maximum lift of 15.45mm on cylinder 2 intake which makes 0.608 in.

[Dan Ruddock]

[1950split]

As it is a driver I don’t think I will rev it higher than 6000-6500 rpm.

[Dan Ruddock]

[Nightshift]

Cause of failure? Installing springs wont tell you what happened. Let the dart throwing begin. You cant look at a picture taken from inches away and throw out I thinks!

[Ohio Tom]

Why would there be no valve roatation?


the valve, retainer, springs, all can rotate as a unit.
As long as there is at least one shim under the springs, the assembly will rotate freely..

I tend to agree that there was a heat treat issue with that one cap.

I would just replace it and move on...

[jason]

I’d change the cap and monitor it closely.