[jalpa_mike]

Does anyone know the diameter of the Jalpa/Silhouette valve adjustment shims?

If memory serves me correct they come in various thicknesses starting at 3.40mm and go up to 4.60mm in increments of .05mm? What is that? Like 25 different sizes? Its late, and my mind is numb....

If someone has a spare shim laying around, maybe they can send it to me. I have a friend that runs a machine shop that might be able to produce them at a fairly reasonable price.

Heck, if I have him produce a hunderd of each size, they might be somewhat affordable.

Mike
Jalpa #12071

 

[rovingtravler]

I don't have shims, but I have valve guides if you need to machine them let me know.

 

[raymond]

Would be a great idea to have them machined, but the problem is the special hardened or covered surface.

I suppose the best way would be to take slightly bigger shim and cut them down to the correct diameter.

Raymond

 

[ltadmin]

Would be a great idea to have them machined, but the problem is the special hardened or covered surface.

I suppose the best way would be to take slightly bigger shim and cut them down to the correct diameter.

Raymond

when I first read this discussion about shims no longer being availible I had thoughts along your lines Raymond. The surfaces are specialy hardened and coated and recreating them is very difficult.

 

[jalpa_mike]

Anyone know what this special coating or process is? Is it something like what they do to a crankshaft? What do they call that? A nibral or nitral coating? Or....

Mike
Jalpa #12071

 

[ltadmin]

Mike,

the shims are ground on both sides flat and to the desred thickness, finished to a certian smooth micron finish and then nitrided for hardness.
You would also need to know what alloy other shims started with before any process's began. Both VW & Volvo, as well as Ferrari & Lamborghini use shims, you could pick some up to experiment with.

 

[jalpa_mike]

I would be really interested in knowing why it is that Lamborghini chose this type of shim, as opposed to the shims that Alfa or Maserati use (the type that sit on top of the valve stem, and the cam bucket sits on top.

I've never seen what the Jalpa valves look like since I've never had the covers off mine. But, what keeps those shims from chattering between the cam lobe and the bucket? Are they magnatized to help hold them in place? Or, is the clearance so small, they don't chatter? My engine seems to be pretty quiet so obviously it must work! hahahaa....

Mike
Jalpa #12071

 

[ltadmin]

The early Lambo, Alfa, Maserati type shims are incredibly difficuult and labor intensive to replace. The shims being on top was a huge design leap forward.

The shims are held in by hydraulic action of the oil and a force know as adhesion, whereby the surface molecules of oil adhere to the shims surface.

 

[jalpa_mike]

I guess I can understand that, giving how much trouble I've had doing valve jobs on my Alfa's and Maserati's! You have to remove the camshafts to get at those little shims under the cam buckets.

At least with the Jalpa, you don't have to remove the camshafts! I can see how that tool Larry posted a picture of, would come in handy..... push that bucket down far enought to allow you to simply remove the shim and put whatever size you need in its place.

Mike

 

[raymond]

Guys, please wait with the shims, a friend of mine is rebuilding his engine.
He has worked at a Engine Overhoul shop and we will have shims specially produced for his engine.
We have been talking this afternoon and he should get a price offer within one or two weeks.

This company is one of the best known and reputated engine shops in Switzerland, they rebuild many oldtimer engines as well. For them it's an easy job to produce the shims, they will measure the surface of the old shims and will harden them as original.

As soon as we have a price we could do an overall order, I think JRV, Valtellina Automobili and Evans might be interested as well.

Raymond

 

[jalpa_mike]

Thanks Raymond. I'll hold off until we hear something from you.

Sounds like you have things well under control!

Mike
Jalpa #12071

 

[lxmichaels]

Hi Guys,

Sorry that I have not been more responsive to this, Real busy lately.

Anyway, I have a small assortment of shims and can take some pix if they will be helpful & I can also take a pix of my 1/2 shaft ( No Puns please)tool for clearance calculations during head reassy.

Maybe later this afternoon.

 

[raymond]

Larry,

thanks for your offer, they already measured the shims, 37mm in diameter.
Normally was 33 for Alfa and 40 for Maserati.
Available shim thickness was from 3,8 to 4,8 in 5/100 mm thickness steps.
This means a full set of shims contains 20 pieces, to be on a save side a garage should have 5 of them, since some of the 16 valves need the same .
Well as always it's a matter of money...

But comes time comes the offer for an entire set...

BTW he found on his engine that the exhaust valves had no sealing and he found many worn valve guides after only 35t Km, the heads are now at the mentioned company (he worked at some years ago) and receive the new guides. He found also 2 rusty cylinders walls but was able to hone them, he also found traces of the original hone process in the middle, which means they didn't a proper bore in Italy.
The car was standing around for some years outside a Saab Dealer, since at every engine position some valves are open, take care your car is parked in dry condition!

Raymond

 

[lxmichaels]

Reference: Here a visual of the shims, they are (as Raymond notes 37mm)

The tool was for quick valve clearance calculations.
Notches on the main journals allow for cam bucket clearance.
The I.D on the middle shaft is the max hight of cam lob centerline.

Teflon wedges hold open the valves.

Install Keenserts on studs the mount the main chain/gear housing... the first time. Include Exhaust studs.

 

[lxmichaels]

Jalpa Cylinder Head

Reference:

 

[ltadmin]

Thank you for the pics Larry (and happy BDAY- )

now you guys can see the greenish/grey coating on new shims. I have never heard a definative answer but I suspect it is some type breakin coating containing graphite.

 

[lxmichaels]

Thanks JR, I wonder if there is a "Seniors" discount on sppeding tix?

Can Timing

 

[ltadmin]

Well, don't know about that except belonging to the Brotherhood of L owners has it's advantages......did your dealer wish you happy BDay???? hahaha!

I have the entire Jalpa (and quite a few more) parts M's on CD, can't figure out how to do a print screen? all help appreciated!

 

[nashbap]

Hello:

I don't know about the Jalpa shims but the early type Alfa/Lambo shims are carburized to achieve the desired hardness. A machinist friend of mine conducted an experiment measuring Rockwell Hardness as each successive layer was ground off .001" at a time and found that the hardness dramatically falls off after only about .005".

Regards,

Nash

 

[rovingtravler]

Larry thanks for the great advise as always! Happy Birthday a day late in Korea.

JRV if you open the manual to the page you want hit the print screen button on the upper right hand site of you keyboard. Then go into start, programs, accessories, paint. Once you open paint go to edit and paste. The image will pop up and you can edit and save it.

David