OST-053: Massaging a 20V Blacktop

[Project D]

I see I'm not the only one to use a dial gauge ! like you said, so muck quicker and easier over the micrometer.

[oldeskewltoy]

(07-30-2019 12:15 AM)Project D Wrote:  I see I'm not the only one to use a dial gauge ! like you said, so muck quicker and easier over the micrometer.

Well... FSM is wrong....

The actual shim availability is no where near as extensive as the FSM would have you believe......




more to come....

[oldeskewltoy]

Well... as I expand to include more 20V head work, I'll need to expand my shim bank.



Here are about 3 heads worth of shims





Up until recently I kept all the 20V shims in a tiny ziplock bag... but with more use, it just doesn't pay to measure all the shims each time, so I bought another shim storage compartment




So with 3 heads worth of shims, the first thing I noticed is the tolerances for the shims isn't very tight. I have 18 shims that fit into the .0748 drawer, but the shims in there vary widely from .0740" - .0750". I have a feeling that as I collect shims, I'll need a bigger shim box - likely including shim drawers to the .0005".

So of the 3 heads worth of shims, I didn't get any of the first 4 sizes, or any of the last 5 - so I've placed an order to fill out my bank a bit more.....



More to come.....

[Project D]

Dan, do you have the dimensions (preferably in mm) of the (lash cap) shims ?
If I'm not mistaken I think they are 7mm OD, 5mm ID, but I'm interested in the depth of the "skirt"

[oldeskewltoy]

(08-05-2019 11:44 PM)Project D Wrote:  Dan, do you have the dimensions (preferably in mm) of the (lash cap) shims ?
If I'm not mistaken I think they are 7mm OD, 5mm ID, but I'm interested in the depth of the "skirt"

8.02-8.04mm OD, 5.02-5.04mm ID, shim skirt depth was between .245mm and .265mm (just about .010") on 5 samples

[oldeskewltoy]

20V shim tolerances are pretty bad. I've now had new, as well as old shims, and in some cases the shims vary by as much as .001" (up to as much as +, or - .0005" either way). I have purchased shims now from a supplier here in the USA, as well as directly from Japan.




with that kind of error, and a still small, growing - but still small shim bank, to set tolerances to within .001" was going to be a challenge... but I did manage to set all the intake with nothing tighter than .010", and nothing as loose as .011", and setting the exhaust side with nothing tighter than .017", and nothing as loose as .018"......

I'll wait.....


I did need a bit of "help" to do it......

[Project D]

.0105" / .0175" within .005" so .26mm / .44mm within .13mm
I never realized how BIG the valve clearance where on the 20v !

If I may ask, why did you choose the Toyota specs (.015" to .020") over the Kelford specs (.30mm so .012") on the exhaust side ?
Or maybe it's a typo on the Kelford spec card ?

[oldeskewltoy]

(08-14-2019 04:25 PM)Project D Wrote:  .0105" / .0175" within .005" so .26mm / .44mm within .13mm
I never realized how BIG the valve clearance where on the 20v !

If I may ask, why did you choose the Toyota specs (.015" to .020") over the Kelford specs (.30mm so .012") on the exhaust side ?
Or maybe it's a typo on the Kelford spec card ?

Quote:I'll wait.....

You found what I was alluding too.......thank you. Toyota has a minimum spec, it is based on a great deal of engineering, and KNOWING the materials that they build the engines with. There is a LOT of expansion on the 20V exhaust valve. Besides Toyota's spec, I've been told by a Uk 4AG engine builder that as well. The Uk engine builder advised me in the past to avoid over ambitious (tight) valve clearances on the 20V valves, especially on the exhaust side.

[oldeskewltoy]

(08-06-2019 01:46 AM)oldeskewltoy Wrote:  shim skirt depth was between .245mm and .265mm (just about .010") on 5 samples

I was being careful with the new tool.... and didn't realize my mistake until today. At only .010" deep the shim could become dislodged, especially on the exhaust side.... but what I was reading as .010", was actually .090". I was just looking at the big needle, and didn't look at the small one... DOH


So with .090" depth, if you have the shims set correctly, you can't toss a 20V shim