Valve Adjustment, Part One

[Dan Sarandrea (Phila)]

One of my recent projects was to do a valve adjustment. My '86 has 39,600 miles on it and I have no idea when the valves were adjusted last, so I put it on the docket.

The shop manual calls for a cold adjustment, meaning that the engine should not have been run in the 6-8 hours preceding the adjustment procedure.

First, remove the intake hose that connects the Air Flow Meter (AFM) to the snout of the plenum. Generously loosen the two large hose clamps and the two smaller hose clamps for the nipples on the underside of the hose: left side is for the Auxillary Air Valve and the right side is for the crankcase vent. I taped over the crankcase hose tee just in case. Carefully wiggle the hose free from all nipples and set aside.

Yellow arrows: With the hose out of the way, pop the cylindrical retainers from the accel cable linkage ball joint (left side) and the throttle linkage ball joint (right side).
Green arrows: Loosen and remove the two 13mm capscrews that hold the accel linkage bracket to the cam top cover.
Red arrows: Loosen and remove the nuts and washers that secure the two FI harness grounds to the cam top cover.

Next, place a shop rag on the frontside of the cam cover area, then loosen and remove the nuts and washers holding the cam cover to the cam box. If you are lucky, a little herky-jerky back and forth force applied to the oil fill snout will break the cam cover away from the cam box. Mine did not budge. I used a wood chisel (sharp, and flat on one side, tapered on the other side) carefully aimed at the thick rubber gasket and positioned at the left rear corner (seemed to be the meatiest part) and tapped it with a hammer...its profile acted as a wedge, separating the cover from the cam box without gouging the soft metal. Remove old gasket (you DID order a new gasket, right?)

The next task is to set up the drivetrain to help you rotate the engine and thereby rotate the cam to the various needed positions. Block the left side wheel(s) as needed, release the hand brake, engage 4th or 5th gear, and then use a floor jack positioned under the passenger side rear wheel's ball joint area to raise the wheel off the ground. Grasp the wheel sort of the like a big steering wheel and rotate it forward (clockwise) and you will see that you are turning the engine over. If you want to, removing the spark plugs will make this easier. Note that you DO NOT UNDER ANY CIRCUMSTANCES want to rotate the wheel and therefore the engine counterclockwise (backwards)...this action is particularly bad for a timing belt engine as there is a real risk of the belt jumping.

Next, draw as much standing oil out of the cam lobe area as you can....I used a $4 turkey baster. The less oil you are fighting the easier it is to remove the shims.

The next task is to record and evaluate your existing clearances. Make a chart that represents the engine and the valvetrain, kind of like this, the numbers being the cylinder number and the letter being Intake or Exhaust:

4E
4I

3I
3E

2E
2I

1I
1E


Start with Cyl No 1 (the cyl closest to the belt end of the engine). Rotate your right rear tire clockwise until the cam lobe closest to the belt end of the engine (Cylinder 1, Exhaust) is pointing up to 12 o'clock. Then use your feeler gauge blades, carefully sliding the blade between the cam lobe and the shim (see yellow arrow below). Eventually you'll find the blade that will fit but the next thickest blade won't fit...record the thickness of the blade that will fit.

Angled feeler gage blades work best for valve adjustments; but if you don't have an angled set, most gage sets allow you to remove the screw holding the blades together so you can use one blade at a time.

Now go to the next cam lobe, which is 1I, and repeat the process: position the lobe pointing straight up by turning the tire, inserting various feeler gage blades in the gap between the lobe and the shim. Be sure to record the blade value that just fits.

When I did mine, here is what my chart looked like:

4E .012
4I .007

3I .011
3E .015

2E .014
2I .009

1I .008
1E .014

The specs for my year car are as follows:
Intake: .011 to .014 in
Exhaust: .015 to .018 in


The rest of the way, we'll be doing readings in Metric, so let's take a mulligan on the above and try it in Metric.

4E .330
4I .178

3I .280
3E .381

2E .356
2I .229

1I .203
1E .356

In metric, the specs for my year car are as follows:
Intake: .28 to .36 mm
Exhaust: .38 to .46 mm


So you can see that the car needed a valve adjustment, as only #3 cylinder was within spec, and that cylinder's valves were only just at the tight end of the spec. On our cars, it is expected that the adjustment values will tighten (the gap values will lessen) as the valvetrain wears.

Stay tuned for Part Two: removing the shims and determining their thickness http://xwebforums.com/forum/index.php?threads/25497/ .

 

[mikemo90]

adjusting valves!!

please...please please use a micrometer to measure the diameter of the shim before installing. a lot of German cars a.k.a. Porsche, vw, and some old school bmw's had shim that were .05 or.010 smaller in diameter and will spit out of the cup at speed. helped trash a few motors at work doing that.
if your close to a Ferrari dealer, they will have shims that are more finite in thickness. having friends at the fiat/ Ferrari warehouse in Burlingame when it was all that, I was given a shim selection kit(Ferrari) that is vastly more precise than fiat. so if you measure to the precise nth of what you need I may have some here.
mikemo90*aol.com

 

[budgetzagato]

Nice write up... waiting for part two.

Not sure if I ever adjusted the valves on my X. I've done it a few times on my DOHC engines including my Scorpion.

 

[Dan Sarandrea (Phila)]

I have been told that the procedure is similar except for how the tool is used.....with the SOHC the lever-like tool is used to depress and hold the buckets, while on the DOHC the fork-like tool holds the spring compressed after its been compressed by the natural action of the cam.

Don't know if that's true as I have never done the valves on a DOHC.

 

[fastx19]

Source of shims.

I have also found the shims used on Volvo's are the same diameter.

 

[Dan Sarandrea (Phila)]

Sources For Shims

It will be in part three of the post, but we can add it here for those that don't make it to part three:

Of course, our regular supportive vendors carry whatever shim sizes you need.

Another option is The Mirafiori Shim Exchange, a mutually supported cooperative started by the FIAT and Lancia enthusiasts who have been participating in the forum at Mirafiori.com for many, many years.

Here's how it works:
1. Make a list of the shims you need.
2. Email the list to the Curator of the Exchange, along with your contact information and mailing address. In your email note that you are a member of XWeb!
3. The Curator will send you the available shims by mail.
4. Remove old shims, install the replacements you got from the Curator.
5. At your expense, mail the removed shims back to the Curator, along with a donation that covers at the very least the to-you postage costs.


Mirafiori member Alvon Elrod is now the Curator of the Mirafiori Shim Exchange. Alvon has authorized me to post this information here on XWeb.

Email Alvon: ventura underscore ace at juno dot com (no spaces)
Call Alvon: eight zero 5, three three eight, one 7 six 7

Alvon also says to encourage those that aren't already participating at mirafiori.com to drop in and chime in.