AMC heads valve warning

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weimarbus
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AMC heads valve warning

Post by weimarbus »

a year ago I bought an MV engine to rebuild from Printmonkey who has fitted a Subaru engine in his American import westy, this engine had apparently had at least a top end rebuild as it had AMC heads fitted. I have just removed the valves to take the heads to have a three angle seat cut and before removing them saw that the valve spring retainers were at very different levels, 2 of the 4 exhaust valves had the retaining collect groves worn away to almost nothing one seemed about ready to drop the valve and 3 of the inlet valves had to have the collet retaining groves deburred with an oilstone before they could be removed through the valve guides.

I'm not sure how many miles were run on these heads but given what has been said before regarding the valve quality it would seem that these are not a fit and forget replacement. I was already going to use the original valves from some old DG heads when rebuilding but it was quite shocking to see the condition of what I removed.

On a positive note the castings are in good condition with no corrosion and the valve guides have no wear, sorry can't posts pictures post p bucket changes.

oilrag
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Re: AMC heads valve warning

Post by oilrag »

Hello,
Im pretty new to this forum ,having only had a t25 since may this year, but not to the world of engine building ,40+ years in the trade ,we (my business) restore,build and machine most stuff sbc to 2cv and are never quiet fortunately.
I have read somewhere on this forum recently ,tho where seems to be beyond current recollection ,(jack D fuelling causes early morning foggyness ),the valves and collets supplied in some wbx amc heads are lets say of inferior metal quality ,possibly down to cost management at raw material stage in mexico where they are cast and assembled..Add a low retail cost requirement in aftermarket spares ,this will inevitably be driving quailty down also ,and good metal aint cheap.

AMC are a very accomplished company ,and produce fantastic castings for many major engine manufacturers.ive re valved,replaced guides,cut seats on many over the years ,most vag cars on todays roads have an AMC cylinder head casting.As an aside we have just purchased for a Chevvy V8 build customer ,a pair of top quality AirFlow Research Heads......£2300 with valves /spring seats and springs...heads cast in mexico by AMC.
One major uk T1/T2/3/4/5 parts supplier you all know wont sell a new head with valves /springs fitted as a single unit,he offers them separately based on experience of potential warranty issues miles down the road after sale.
(for good reason no doubt) ,
However ,good quality valves are available for not too much cash.but many other things in a wbx cascade the cost of replacing them rapidly ,ie studs ,high gasket costs ,there's no cheap answer im afraid, good bits cost good money ,the experienced guys on here all offer fantastic advice and guide the less knowledgable ,i can add a little i hope ,with a bit of courage most can be quite good at diy and succeed .
Nothing wrong with amc heads ,the valves and collets wont last galactic k in them ,but they need some prolonged abuse of high revs/load with low oil levels causing excessive high temps ,poor oil quality, zero or shambolic maintenance all assist the metals to wear fast,and fail with no warning.If an engine is unknown on purchase ,assume nothing is perfect ,treat it like a poorly patient and nurse it back carefully given at the very least its 25 years old ,and possibly been in hands of a few well meaning but useless numpty's '
There is a potential valve collet problem ,but it isnt in every wbx or boxer engine ,collets along with valve stem can be inspected and collets changed without removing the heads ,valve replacement will become a top end overhaul and a dance with the devil.
Cheers
G
'89 wbx DG lpg, 5 speed, twin slider, hi top.
There's always someone who has a bigger or better one .

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CJH
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Re: AMC heads valve warning

Post by CJH »

Some good advice and photos were provided by fellow forum members in my build thread - first photo here. The photos convinced me to swap the valves for TRW valves from Brickwerks. I swapped the collets too, just in case.
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itchyfeet
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Re: AMC heads valve warning

Post by itchyfeet »

Yes its a well known problem in WBX rebuild world.
these pictures from Marco Mansi.
Best reuse old valves or buy new, plenty of scrap heads about to rob valves from.

ImageAMC Valves 2 by Paul_Barr, on Flickr

ImageAMC Valves by Paul_Barr, on Flickr
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weimarbus
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Re: AMC heads valve warning

Post by weimarbus »

Yep that's what I found, mine were worse, luckily I have some TRW valves from my old DG and will use the original vw spring retainers and collets.
1985 hi-top 2.1MV with DG carb and LPG
1955 trials buggy with 1.9 DG high lift cam and twin dell's

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itchyfeet
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Re: AMC heads valve warning

Post by itchyfeet »

If only we had somebody actively adding to the WIKI :lol:
1988 DG WBX LPG Tin Top
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itchyfeet
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Re: AMC heads valve warning

Post by itchyfeet »

oilrag wrote:Hello,
Im pretty new to this forum ,having only had a t25 since may this year, but not to the world of engine building ,40+ years in the trade ,we (my business) restore,build and machine most stuff sbc to 2cv and are never quiet fortunately.
Cheers
G

Hi Gary.
Would you by chance be planning to build any more WBX?
There is a deperate need for quality repaired WBX that are affordable, not many can afford to pay for a full rebuild which might be £4K+ but the 1K end is shocking and the 2K not much better.
It sounds to me like somebody with an engineering company who has an interest in WBX could be very busy with work.
There is lots of good advice on here but hands on professional engineering knoledge is in short supply for the WBX, mostly its just amateurs like myself publishing their experiences.

cheers
Paul
1988 DG WBX LPG Tin Top
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oilrag
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Re: AMC heads valve warning

Post by oilrag »

Hello paul ,short answer ,yes in time tho not in near future ,our current workbook is full till end of march/early april next ,altho we do get jobs fall away at last min those spaces usually allow us to catch a breath and tidy up , as you are aware timescales on these jobs vary,usually dependant on parts supply.personally i managed my own rebuild over a 4 month period from march to to late june mainly waiting on new bits, and didnt get it installed till early sept ,i cant see the camshaft availabilty helping matters either ,i was lucky and fell on a new one from heritage ,but only dg spec,the other option of fitting earlier cams and bolting to a gear is very do able but expensive component-wise. cam follers present another dilemna,the kbs followers seem flawed somehow giving varying drain down times ,my personal pref would be to use solid and put up with adjustment maintenance,refacing old followers is virtually pointless,we tried on both a long one and the shortest,and the hardening was so thin on the long one we broke thru very easily no hardenening whatsoever on the shortest,.i wont bore with tech stuff on metallurgy but the initial manufacture of the wbx/boxer was robust ,but not rolls royce quality in materials which would allow electro hardening to be applied.,A factor is the alarming differences in worn followers height ,i have noted on 4 engines ive stripped this year differences of +/-3.5 mm per follower across an engine ,that says the hardening has gone ,same with cams ,a brand new cam i obtained had the two centre lobes .30 mm taller ....than outer lobes.......more metal to counter the poorer oil supply ,an effort to extend the cams and therefore the engines life i guess.on measuring old cams all had less height on centre pair of lobes ,backing up my findings on the new one. that wear equates to swarf in the sump,/filter ,emphasising the need for frequent oil changes I am happy to offer help/advice etc and will respond to enquiries quickly.,.G
'89 wbx DG lpg, 5 speed, twin slider, hi top.
There's always someone who has a bigger or better one .

henryb
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Re: AMC heads valve warning

Post by henryb »

Got a great pair of heads off oilrag, all nice and clean no cracks , this is whats he's done :

, both have been cleaned ,lightly re-faced ,valves re lapped in ,new collets and all inlets have new stem seals fitted.,all springs in service limits , all threads are good and clean.no cracks brtween seats of valves ,valve guides are good

Very pleased with my purchase from oilrag who knows his stuff

tencentlife
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Re: AMC heads valve warning

Post by tencentlife »

Here's a new blog post with the facts about AMC heads:

https://intrepidoverland.com/amc-wbx-cylinder-heads/" onclick="window.open(this.href);return false;

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itchyfeet
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Re: AMC heads valve warning

Post by itchyfeet »

Thanks Chris :ok
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silverbullet
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Re: AMC heads valve warning

Post by silverbullet »

Same. Old. Story...wbx are not cheap to do properly, they eat parts and everyone wants cheap AND perfect.
There is currently no aftermarket master pattern for the 4-rivet "big flange" camshaft.
All the cam blanks come from China (fact) and unless someone wants to commit to £2k of patterns and a minimum run of 100 cams (about £5k) its a non-starter.

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itchyfeet
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Re: AMC heads valve warning

Post by itchyfeet »

silverbullet wrote: There is currently no aftermarket master pattern for the 4-rivet "big flange" camshaft.
All the cam blanks come from China (fact) and unless someone wants to commit to £2k of patterns and a minimum run of 100 cams (about £5k) its a non-starter.

This surprises me, to big companies £7k is nothing why hasn't one of them done this? got to be money in it.
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