Rocker arm 2ltr aircool problem

Post by **camper** » 25 Feb 2006, 16:39

I replaced the inlet valve for no 1 cylinder but the problem of the rocker arm screw tappet adjuster coming off the valve stem has not been resolved.The rocker arm slides across the shaft of the valve stem onto the spring retainer.This happens when i screw for adjustment for hydrolic tappet setting.And when the engine is firing.I checked to see the push rods are seated and the rocker arm assembly.On looking at the Haynes manual it shows a spacer and shims on each side from the rocker shaft to the inlet and exhust rocker.On my own cylinder heads on each rocker assembly there is only a spring on the shaft between the rockers .Advice would be gratefully appreciated to tell me if this is correct.Looking at the haynes picts its not the same

Post by **HarryMann** » 04 Mar 2006, 13:50

Bentley Manual shows:

For the Air-Cooled (CV) USA/Canada engine, shows a spacer and a couple of shims either side. Cannot see a spring in the diagram (15.3)

Post by **camper** » 04 Mar 2006, 15:29

Yes thanks for the reply.I have been over and over this problem and it looks like a cheap way that some engine recon merchants get a quick fix .The engine is a recon with about 10.000 on it.It was sadly negleted by its previous owner due to missing tinware and lacking cooling deflectors.It was used for short trips the engine did not fail but on examination it had overheated.I replaced the exhust valves and obtained tinware and flaps .On starting there was no problems but when the engine reached its correct tempreture on a road test a horrible noise came from no 1 cylinder.On looking at the rocker arm on the inlet valve the adjuster screw was trapped between the the valve stem and spring retainer cap.Since then i have replaced that valve due to it being bent .I am in the proccess of trying to obtaining some standard rocker shaft assemblies which will have the spacer.On looking at various manuals and vw racing parts sites for info solid rocker shafts are obtainable Still not sure how this spring arrangement lasted so long on the heads .I think when i dismantled the rockers i changed the tolerances as when it was supplied by the reconditioners.I am a little concerned the rocker arm may have changed its angle slightly when the problem occured but the push rod is straight .I am waiting parts which will include rockers so as soon as i can get them with the shaft and spacers i will try again.

Post by **camper** » 04 Mar 2006, 15:42

Oh the other concern as to why it had valve damage with this event.Was there air in the hydraulic cam follower ?even though i bleed every one .The hydraulic follower on that valve is not spongy it is solid anough when two turns are adjusted .But when its adjusted with no 1 cylinder at top dead the existing rocker arm adjusting screw has an inclination to start sliding off the valve stem.I was going to replace the hydraulic cam follower at the same time i put the spaced and shimed rocker shaft .I am a little paranoid about it all .I have seen a topic that said give it approx twenty mins after adjustment before starting.

Post by **HarryMann** » 04 Mar 2006, 18:32

I am going to pmail one or two people who may know much more than me about this engine (ahsa know nothing about them

)... give it a day or two and see what comes back?

Post by **camper** » 04 Mar 2006, 19:28

Thanks for your input on this problem.The engine is a recon from a well known supplier in south london .The heads are AMC that appear new but with rocker shafts with springs that are aprox 3 1/2" uncompressed ie not on the shafts.When i removed the rocker gear and shafts i kept them in order but may mixed up some of the push rods.The Haynes manual and common sense advices keep them in order.I am asuming this is becouse the pattern of wear to each part.

Post by **cumbriankeith** » 04 Mar 2006, 20:47

"HarryMann" PMd me about this but I'm afraid I can't shed much light on this issue - I've only done a basic top-end rebuild on a CU engine and it all went back as standard and ran happily for 25k miles till I recently had a complete rebuild done by Laurie Pettit. I did have a few probs with the hydraulic cam followers and ended up replacing them all - but still had noisy ones from time to time due to intermittent use. BTW the consensus about the preload adjustment is not to use 2 turns but half to one - once you know they're properly pumped up, that is. Bench bleeding them is an art and no guarantee that they will perform right either. There are a few articles on some American websites on how to treat hydraulics eg:
http://www.bostonengine.com/articles/hydraulicll.htm

My new engine has solids and a torquier cam but I've only done 800 miles so far and it's still settling in. Getting the timing and carbs set up right for it is a whole other story for another thread tho...

Good luck with it all!

Post by **HarryMann** » 04 Mar 2006, 20:59

Thanks Keith,

New wiki link on carb jetting (Aircooleds)

http://www.club80-90.co.uk/wiki/index.p ... ting_carbs

Post by **Martin** » 04 Mar 2006, 21:24

i have seen this before, my own bay but with a cu in not cj
my rocker shaft and rocker arm were bent.
as for the tappets there a pain in the a*** at the best of times
i know this isn't in any manual but i normal adjust them by feel and set them to just touching (rightly or wrongly)
the man you need to talk to is andy aka the sheriff but he don't come on here anymore but his numbers is in the links page i think Andy at the secret hideout.

Post by **camper** » 04 Mar 2006, 21:31

Thanks keith for your reply and your help in passing on to me some good parts.When i get the replacement rockers with shaft and spacers i will adjust to your advice .With it standing up while waiting for them to arrive hopefully the hydraulics will still be pumped up.Once its shimmed up between the shaft spacers i am more confident the rocker will keep on the shaft.I was looking at some of the performance product suppliers and there replacement valve train parts.It said the standard parts with the spacers and shims can cause problems if a shim breaks the rocker arm can slide off the valve stem on to the spring coller.So with this spring arrangement which i have on my shafts i would imagine it may have been only a matter of time for it to happen.Thanks everyone for your help on this.

Post by **camper** » 04 Mar 2006, 21:36

Martin wrote:i have seen this before, my own bay but with a cu in not cj
my rocker shaft and rocker arm were bent.
as for the tappets there a pain in the a*** at the best of times
i well know this isn't in any manual but i normal adjust them by feel and set them to just touching (rightly or wrongly)
the man you need to talk to is andy aka the sheriff but he don't come on here anymore but his numbers is in the links page i think Andy at the secret hideout.

Well thats a coincidence Andy is sending me a set of rockers shafts with spacers .

Post by **camper** » 09 Mar 2006, 19:21

Ref two turns haynes manual hydraulic cam follower rocker screw adjustment.I would suggest fully pumped up 1/2 to 1 only/ I ran the cu 2ltr today no problems with the replacement rockers spacers and shaft supplied by Andy The Secret Hideout! bus freaks.

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Rocker arm 2ltr aircool problem

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