Lash caps

[fekbmax]

Lash caps, friend or foe ?
When to use them and when not to ?
Opinion's ?

[cammerfe]

Since lash caps 'spread the load' they are ALWAYS your friend. And lash caps were the original way to set the lash on cammers. They make the rocker much simpler and, in my opinion, the only way to go.

I always include them in the build when dealing with rocker arms.

KS

[jayb]

I like lash caps, but they can be dangerous.  When I was removing a rocker shaft on my SOHC at Drag Week in 2008 (to replace another Dove rocker ), one of the lash caps stuck to the #3 intake rocker for just a moment as I lifted the shaft out, and then dropped unnoticed into the #3 spark plug hole.  When I re-assembled the motor and found that, I wasn't sure where the lash cap had gone, but figured it came off somewhere so I just replaced it.  When I fired the motor it became obvious where it had gone    I pulled the top end of the motor back apart and spent an hour fishing in the cylinder to try to get it out with a magnet, but no luck.  It was Drag Week, and I was running in first place in my class and didn't want to quit, so I reassembled the engine and ran the car making all that racket anyway, hoping that the lash cap would blow out the exhaust.  You should have seen the looks I got from the track officials at the starting line LOL!  Anyway, halfway down the track the noise from the motor stopped, and I thought that the lash cap had gone out the exhaust, but fifty miles down the road the awful clattering came back; apparently the lash cap had embedded itself in the piston or chamber and stuck there for a while, then popped loose. 

It never did come out, and after burning up more Dove rockers and eventually running out of spares I had to quit the race.  When I finally got the motor apart a couple months later, the lash cap had been beaten down into two tiny steel balls.  The chamber and piston were pretty much wrecked.

Moral of the story - put the plugs back into the spark plug holes if you are disassembling rocker systems with lash caps.

[KMcCullah]

I like em' for correcting rocker arm geometry. I've also used lash caps to fix worn out factory adjusters. You know, the ones where the interference fit in the thread is gone and the rocker arm constantly keeps losing its lash. Just add a .080 lash cap and back the adjuster off until the valve lash is correct again. Most of the time the interference fit in the threads is noticeable again. But it screws up the geometry.

[newfalconowner]

so they will help with pushrods that are abit to short? my adjuster threads aren't even on my rockers

[newfalconowner]

heres a picture of the adjusters and pushrods,, they are are pretty close to the same as this

[66FAIRLANE]

Upon disassembling my rocker gear after a bent a pushrod I noticed all my valve tips beaten to hell (out of box Edelbrocks, .590 solid, Erson rockers). I put rags around everything but the valve tips then tidied them up with a 4" grinder! Added lash caps and away I went! Was like that for years. When I re did the heads and valve springs I put em back on.

I do like them. Nice and hard, nice and flat, spread the load and let the roller have full contact across its width.

[machoneman]

Other than the SOHC and to 'repair some bad tips, lash caps are cheap crutch IMO. Aside from coming adrift as Jay noted, adding weight to the valve tip is a bit counter-productive as one will never see a beehive equipped, tiny titanium retainer race engine with them.....and for good reason.

JMO but they do have their places!   

[Drew Pojedinec]

so they will help with pushrods that are abit to short? my adjuster threads aren't even on my rockers

Lash caps are what .080 at the most?
Will make a small difference, would probably be better with longer pushrods.
Not all valve spring keepers will allow lash caps either.

Easiest way to see how much of a real difference it'll make would be to take your valve lash, of .020 and add in the lash cap thickness.  So lets say you have .100
Take some feeler gauges and make up a stack of them that equals .100 and put it under the rocker.  See what it looks like.

[Barry_R]

Other than the SOHC and to 'repair some bad tips, lash caps are cheap crutch IMO. Aside from coming adrift as Jay noted, adding weight to the valve tip is a bit counter-productive as one will never see a beehive equipped, tiny titanium retainer race engine with them.....and for good reason.   

Not necessarily accurate.  Not sure about current stuff, but not too long ago there were a fair number of Cup cars that ran selective lash caps instead of having adjusters.  Several suppliers still show them as available in .001 increments between .060 and .080 for adjustment purposes.  Weight gain is nominal and only related to the skirt portion of the cap since you are "replacing" valve tip length with cap thickness.

[Drew Pojedinec]

Not drag racing or collector car specific, but I will mention that it is rare to see an industrial engine, or any engine designed for really long service intervals that does NOT have some form of lash cap.

[machoneman]

Sure fairly low speed, really big CID industrial engines used in a variety of applications of have had lash caps for ages as they do serve a purpose. Not so much on any factory automotive engines today as none use them.

As for racing, I agree with Barry that NASCAR builders did use caps until recently as my understanding is most builders have moved away from using them. Not exactly sure why but perhaps in the search of the ultimate low valve train weight they have done so. Like I said they do have a purpose but, except for unusual or specific circumstances, they seem have fallen out of favor.   

One great alternative are the valve locks that are made with a top on them that rides directly under the rocker's tip, saving the actual valve tip from wear.  We don't really hear much about them and I do wonder if anyone here as used them or if they are still available. 'Course these really don't offer any valve adjustment like a true lash cap.