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Newbie challenge - removing heads to inspect tappets
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john 33_16v
16 Valve


Joined: 27 May 2005
Posts: 1406
Location: herts, uk

PostPosted: Fri Feb 24, 2012 9:18 am    Post subject: Reply with quote

Brit01 wrote:


One guy made an access hole on each cam support so he could prime the heads with oil on dry start ups - also useful for draining I guess.

16v - a substantial amount with the 4 cams I guess.



16v heads drain pretty well because of the drain pipes to the sump at their bottom back corners which is good in terms of circulation/ oil changes, but probably not so great for cold start ups when the cars been standing.

I guess the exhaust cams sit in a bit of oil, which explains why it's the inlet cams that are more prone to wear.

John
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Bobkelso
Alfa Sprint


Joined: 09 Aug 2011
Posts: 190
Location: Milan - Italy

PostPosted: Mon Mar 24, 2014 12:08 am    Post subject: Tappets to be changed? Reply with quote

A friend here is going to rebuild two spare heads for his Alfa 33 1.3 i.e.,
when heads will be ready he is going to swap them on is car, and
I also probably will do the same this summer for my 33 1.3 VL carbs.

The first 2 spare heads that are now on preparation are
from a 130.000 km engine and result to be in good shape,
only minor work is been done by the head specialist
(for example new rubber seal for the valve steam);
cams are perfect, valve, seats, spring are ok, hydraulic lifter retain
the oil (you cannot depress them without the aide of a vice),
but the tappets (lifters) upper surface is slightly signed,
I have not taken a photo, the damage is not as much as
the tappets in the photos in the Brit01 discussion,
but you can see a clear sign where the lobe hit the tappet,
I think the sign is no more than 0.1-0.2 mm deep in the surface,
and is a perfect line, not a circle, so I think the sign
is blocking the normal tappet rotation and so the damage will
speed up more than usual (when tappets can still free rotate).

My question:
the tappets damage seems to me a “border-line” situation,
they are not perfect but not so bad,
I have not enough experience to say if tappets and cams
will last other 130.000 km or tappets will destroy themselves
and cams (actually like new) in 30.000-40.000 km, so better
to change them anyway?
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Brit01
Gold Cloverleaf


Joined: 24 May 2010
Posts: 665

PostPosted: Mon Mar 24, 2014 2:56 am    Post subject: Reply with quote

Change them!
Not worth the risk. Piece of mind also.

Are you looking at ina or alfa originals?
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Bobkelso
Alfa Sprint


Joined: 09 Aug 2011
Posts: 190
Location: Milan - Italy

PostPosted: Mon Mar 24, 2014 1:50 pm    Post subject: Reply with quote

Hi Brit, we are watching for INA tappets available
on Ebay, because Alfa tappets are quite expensive
(considering that here in Italy you can still find
complete engine low mileage with good tappets
for reasonable price)

On INA tappets (new) codes I open a discussion here:
http://www.alfa-pages.co.uk/viewtopic.php?t=7205

Tryng to find if we can use these tappets easily available:

INA 420 0022 10 => 70gr (used on old and recent VW group engine)
INA 420 0041 10 => 65gr (used on old BMW and Opel group engine)
INA 420 0043 10 => 56gr (used on recent and new VW group engine)

On some vw forum people talk about these as inter-changeable,
on other they say the 56gr is not optimal/stable on old motor,
but I know you are positively running on your boxer the previous version
(with old INA code and quite similar weight) of this light tappet.

Instead of "correct" spare:
INA 420 0056 10
that is expensive as alfa tappets, probably heavy, and no more avalaible Confused
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Bobkelso
Alfa Sprint


Joined: 09 Aug 2011
Posts: 190
Location: Milan - Italy

PostPosted: Wed Mar 26, 2014 10:40 pm    Post subject: Reply with quote

Hi, today head specialist managed to
save old original tappets with a quite simple work:
by removing 0,2 mm of material with rectify machine
he renew the surface perfectly (alfa original tappets
are quite thick, at least 2mm, it can be done safely),
after that he empty them from old oil, put in new oil
and is actually doing an overnight hold-pressure test
before close the complete rebuilt heads.

My test of INA tappets seams to be postponed
at next heads rebuild Shocked

Ps.: Brit thanks for the suggestion about the
3/8 17mm socket wrench + 3/8 to 1/2 adapter
to reach the most hided head bolts when
motor is in the car, it works very well,
it will be useful at torque and re-torque Very Happy
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ZeNiTh-PbArM
Alfa 33


Joined: 14 Mar 2003
Posts: 388
Location: Paris, France

PostPosted: Thu Mar 27, 2014 2:22 pm    Post subject: Reply with quote

Hello Bobkelso,

I wouldn't use tappets wich have been ground down.

Although the lower height is not much of an issue, the surface finish has to be right for the lubrication film to operate correctly. Too smooth and the lifter will not rotate under the pressure of the cam and will wear down very quickly.
Too rough and it will scratch the cam and accelerate wear. This is a parameter you want to keep within specifications.

Most preoccupying is the surface treatment of the lifter. OEM lifters are heat-treated to achieve a harder surface and avoid premature wear of the surface. Once the wear has gone through this thin layer, the wear rate increases drastically until the cam finally punctures the tappet.

How thick this hardened layer really is, can be measured with hardness tester although I haven't done it personally - Since case hardening thickness depends on treatment time and time meaning money in mass production, it would be my guess that the hardening thickness is at the minimum to allow an average engine life.
I wouldn't risk killing a perfectly good engine by installing tappets which have a lower life expectancy.

I would use tappets from INA, preferably the lightweight ones.

All the best,
zp
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RFlower
Alfa 33


Joined: 17 Feb 2004
Posts: 432
Location: S of France

PostPosted: Thu Mar 27, 2014 2:59 pm    Post subject: Reply with quote

I coldn't agree more with Ze-Pb.

The most critical property of the tappet is probably the case hardening and finish of the contact surface, and your specialist has just removed that.

Unless he can case harden the surface to the original specification I recommend you get one or more new tappets.
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Bobkelso
Alfa Sprint


Joined: 09 Aug 2011
Posts: 190
Location: Milan - Italy

PostPosted: Thu Mar 27, 2014 4:28 pm    Post subject: Reply with quote

Thanks very much for advises,
and these where also our doubs.

Head specicialist talked with another
motorist that have already done this operation
on (lightly) scratched alfa boxer hydraulic tappets,
actually he is still runing his 33 with non apparent problems
but I know this in not a conclusive argument, may be he is just lucky.

They assumed that these thick and old tappets have'nt surface hardening, Shocked
but only a good selection of steel (more good than today one),
and that only cams have hardening because they have stress
concentrated on a more restricted area,
It seamed reasonable to me, but I have no evidence,
also your idea could be right Question Actually heads are closed
with grease and gaskets, few day and they will be on the car,
so we will do this as an experiment..

About surface roughness, it is another interessant point.
I think head specialist it is been on the 'high finish' side,
Ps: new tappets aren't almost mirror like or they became
like that where cam impact after few km?

This first motor will be tested on a 33 of a friend,
he decided this way and I also was favorable,
we will report how this 'experiment' works,
but as he will do only 5000 km at year and
with high quality oil, probably verdict on
tappets could be postponed by years.. Rolling Eyes

PS: for next motor rebuild, I hope to do personally
or have from someone more exact misuration of the stroke
of the hydraulic part of INA and Alfa tappets
(height at full depressed and at full extended).
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ZeNiTh-PbArM
Alfa 33


Joined: 14 Mar 2003
Posts: 388
Location: Paris, France

PostPosted: Fri Mar 28, 2014 12:48 pm    Post subject: Reply with quote

Hello Bobkelso,

All 33 camshafts are cast iron, which are induction treated to 50-55 HRC hardness with a case thickness around 1.5mm.
Tappets are more in the range of 60HRC.

Tappet wear is highly dependent on the use and oil quality /oil changes. On my own 33 I've replaced a batch of tappets with more than 600 000 kms without any signs of surface wear. Reason for replacement was a ticking noise due to internal wear of the hydraulic element.
You might get away with ground tappets if you don't drive around much and care about your engine. On the other hand, tappet failure will destroy the cams and generate enough metallic particles in the oil to ruin the rest of the engine.

New tappets from reputable manufacturers (not counterfeit, not cheap chinese stuff) are not of inferior quality compared to OEM. Side-by-side comparison will tell you that new tappets are better than the old ones, and on top of that will tolerate thinner oil that the OEM ones.
Most of the time tappets are replaced because they have severely worn down...and the cams are seldom replaced due to obvious cost reasons. New tappets are then quickly destroyed by scored cams and the tappets get bad reputation as a result.

By the way, OEM lifters thickness adjustment range is between 16.2 and 19.4mm. INA is exactly the same. Nominal operating thickness on most engines is around 17.2mm for exhaust and 18.0mm for intake.

Regards,
zp
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ZeNiTh-PbArM
Alfa 33


Joined: 14 Mar 2003
Posts: 388
Location: Paris, France

PostPosted: Fri Mar 28, 2014 1:09 pm    Post subject: Reply with quote

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Bobkelso
Alfa Sprint


Joined: 09 Aug 2011
Posts: 190
Location: Milan - Italy

PostPosted: Fri Mar 28, 2014 2:09 pm    Post subject: Reply with quote

Thanks for information about long experience
with these motors and for measurements Smile

PS.: you mean that all INA tappets 35mmx26mm we are talking
about could have same adjustment range (as a common 'standard')
of alfa one (between 16.2 and 19.4mm), or you have see that
in a specific model and I should check if few differences are possible?
(If they are no standard measures, I was thinking
to buy a single INA tappet just to measure adjustment;
now I was also thinking about to do some trivial test on an
old alfa used one to see if it has or not surface hardening)

I ask about adjustment because next motor with
head rebuild will be one of a 33 with lp-gas and
so the adjustment range of hydraulic tappets
equal to original (or at least between a 0,5mm difference)
could be an important parameter for long life
of the motor if valve seats will wear-out a bit.
(until now lp-gas runs fine on boxer, no anomalous
valve seats wear, but I know that valve seats could wear
more rapidly if low lp-gas/air ratio occurs by bad regulation
and combustion chamber becomes over-heated)
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ZeNiTh-PbArM
Alfa 33


Joined: 14 Mar 2003
Posts: 388
Location: Paris, France

PostPosted: Fri Mar 28, 2014 7:07 pm    Post subject: Reply with quote

Hi,

The tappets 420.0043.10 and 420.0022.10 both comply with the dimension of OEM tappets.


For both the surface treatment is compatible with the OEM camshaft
Others I've tested have compliant internal dimension but the internals are not compatible with the boxer engine.

regards,
zp
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