Race Engine Forum UK

Don't bevel the oil holes! They need to be closed once the cam actuates the valve. The oil pressure pumping them up should be applied only when the valve is not being opened.

Ok that makes sense. but just to note that the OE tappets do have an upper bevelled oil hole.
My INA aftermarket lightweight tappets are standard holes.

Just curious of why Alfa would have a bevelled edge on them.

Also the old OE tappets taken out are 12 grams or so heavier than the OE tappet supplied from Argentina with a distinctive different hig bevel on the oil hole! Both OE?? Came with no box/markings or anything! At least the INA came properly packed, sealed and marked.
Maybe the upper bevel helps to keep the oil pressure high when the valve is closed but on the other hand could have a higher chance of bleeding more when the valve is open.

Regards

Don't worry too much about these details, Chris.

The bevels are -in this case- just there to provide a platform to drill the oil hole. They have no other function, since there is no oil feed groove around the bore. It is in the tappet. It would be very unlikely that the bevel would be exactly in front of the oil feed hole. Even if it was, the only thing that would happen is that the tappet would get oil pressure for a couple of mm's longer before it would be isolated. Not ideal, sure, but not dramas either.

It is not uncommon for OE parts to have no markings, since they come in large boxes (marked) with trays of parts inside.
Anyway you got yourself the INA's. They are both marked and have no bevels to lose sleep over. Good.

regards
Tom

Don't worry too much about these details, Chris.

The bevels are -in this case- just there to provide a platform to drill the oil hole. They have no other function, since it there is no oil feed groove around the bore

Thanks Tom - good to hear that from someone at last. Posted the question and photos on many forums and never received any feedback.

I was thinking if I need to buy these OE tappets and if the bevelled hole performed a function.

The lightweight INA ones are great IMO as they lighten the valvetrain significantly and put less stress on the springs at high revs also.

They are both marked and have no bevels to lose sleep over

Once it's all back together and working smoothly with no ticking my sleep pattern will return to normal!
My brain is like a noisy valvetrain while sleeping at the moment!

What Tom says. They rotate so indeed, the chance the bevel is in front of the feeder hole is minimal and it will be a short period, maybe 5 openings or so?

If you look at the wear marks on your old tappets and the old cam support, it's obvious the tappets have been tilting. If they can tilt, I don't think they will be able to get enough of the oil pressure in the tappets.

Actually, the mechanism that governs the valve lash is inside the tappet and the value of the lash is set in the shape of those parts. The oil feed into the tappet is just there to power the mechanism during 'valve closed', not to time it and/or to influence valve lash.

regards
Tom

If you look at the wear marks on your old tappets and the old cam support, it's obvious the tappets have been tilting

Yes I see that now. Also now trying to source the second cam box to replace the other side as all tappets show signs of tilting wear (but only one was ticking due to more wear than the others).

Don't want to wear out the tappets prematurely before I get a better cam box on with good bores.

A bake in the oven to remove the old stained oil and set the new paint worked a treat.
The oil stains turned into a flaky dusty film easy to remove. There was a little smoke eminating from the oven though!!! Lol

It was previously washed in kerosene/hot water,detergent/paint thinner but didn't shift everything.

Then a wash in the dishwasher worked very well.

When I took it out and squirted WD40 down the tappet oil passages while it was still hot I was shocked how much black gunge continued to come out.

Back in the dishwasher for a second cycle!

(Yes wife is not aware of this!!) What she doesn't know won't hurt her!

TomLouwrier wrote:Actually, the mechanism that governs the valve lash is inside the tappet and the value of the lash is set in the shape of those parts. The oil feed into the tappet is just there to power the mechanism during 'valve closed', not to time it and/or to influence valve lash.

regards
Tom

From what I was told, if you put too much pressure on the tappet and the hole is still "open" more oil can be pushed back against the spring pressure inside the tappet. You test the tappets by the method Guy described, slowly compress them in a vise. Oil does come out of the feeder hole if you do that. Maybe it's not significant enough to matter, but I wouldn't want to mess with it unless I had to.

Quickie - Chris (Brit01)

have you measured the noisy tappets - across diameter - in various places (with a micrometer) and compared with the new ones?

Sorry if you have and I missed it, the trouble is I get less and less time to keep up with the threads I want to..

G

Yes all tappets were measured in the workshop, old and new with a micrometer.

new noisy one and old noisy one also.
Gap calculated between diameter of tappet and bore also.

Old tappets were quite worn obviously.

This spare cam box with the INA tappets (including the new noisy one) are all within specs. Old ones plus bores were way out and laterally worn.

Thanks Guy and no problem. I know the feeling - trying to find the time also just between my 17 month old/wife/work and fixing the car, changing nappies etc etc etc.


Results:

Factory specs:

Bucket diameter: 35 mm - 35.025 mm

Tappet/bucket gap 0.025 mm - 0.066 mm

Spare used cam box:

35.020mm internal diameter
gap between new tappet and bucket: 0.050 - 0.058mm

Current problematic cam box:

gap between tappet and bucket: 0.070 - 0.080 mm
and oval.

Thanks on all counts Chris.

G

No thanks to you Guy.

And the rest of the team.

I'll keep you updated.

cam box installed with cams and tappets and attached to the head ready for assembly.

Just missing a head gasket!!

Chris! Chris! Chris!

What's this then? Are you showing us here that we went through all this trouble with you, but you did not even hog out the inlet manifold?
Oh, the shame! The disappointment!

:-)))

wink, nudge,
Tom