Valve Adjustment Specs

[dlaing]

the valve clearance specs listed here are wrong. The sticker on my bike (US/ california spec, 2004 model v 11 sport) says .15mm IN; .20mm EX

what's wrong with the recommended values?

they also say 5/40 oil, there's a point of contention for the shadetree mechanics here!

84668[/snapback]

Nothing is wrong with the .15mm IN; .20mm EX

It is good to know someone is getting it "right", if there is such a thing.

The problem with the recommended values is consistency from Mother Guzzi

From the "WORKSHOP MANUAL" that came out I believe after the Rosso Mandello and before the LeMans, they recommend

TAPPET BACKLASH After the first 300÷1000 mi and after evey 6000 mi, or when the timing system becomes very noisy, check the backlash between the valves and the equalizers. Adjustment must be carried out when the engine is coil , with the piston at top dead center (T.D.C), in compression stage (valves closed). Work as follows: •    Remove the head cover “A” by unscrewing the eight screws”B” •    Loosen the nuts “C”; •    Loosen or unscrew the adjustment screw “D” until you obtain the following backlashes: - Intake valve 0,10 mm; - Exhaust valve 0,15 mm This measurement is effected by inserting a feeler gauge “E” between the rocker and the valve. Remeber that if the backlash is greater than the prescribed one, the tappets will be noisy. If it is less, the valves will not close well, thereby causing the following problems: •    Loss of pressure; •    Engine overheating; •    Valve burning-out, etc

[rocker59]

The sticker on my Nero Corsa's rear hugger recommends 0.15 intake and 0.20 exhaust.

 

However, the owner's manual says 0.10mm intake/0.15mm exhaust.

 

The Workshop Manual also recommends 0.10mm intake/0.15mm exhaust.

 

 

I'm not sure where it is set right now. I'll experiment with the two settings and see how it runs on both when I service it...

 

I know my carb'd Sport 1100 runs much better at 0.10mm/0.15mm than at the USA spec 0.05mm/0.05mm recommended in the owner's manual...

 

[Ryland3210]

It looks like the bottom line on head fastener torque is 29.5 foot pounds.

 

Anyone know the torque spec for the rocker arm locknuts?

[Guest ratchethack]

John, having taken the rocker shafts out for torquing the heads, I don't recall any such thing as "rocker arm locknuts", and nonesuch is shown in the Service Manual??

 

Unless you're referring to the valve adjuster locknuts?? I give these a good snugging, and Bob' yer Uncle.

 

The rocker shafts are retained by bolts (the manual refers to 'em as screws) that get 6-8 Nm. At least one over-zealous poster has over-torqued these and regretted it.

[Ryland3210]

John, having taken the rocker shafts out for torquing the heads, I don't recall any such thing as "rocker arm locknuts", and nonesuch is shown in the Service Manual??

 

Unless you're referring to the valve adjuster locknuts?? I give these a good snugging, and Bob' yer Uncle.

 

The rocker shafts are retained by bolts (the manual refers to 'em as screws) that get 6-8 Nm. At least one over-zealous poster has over-torqued these and regretted it.

 

Sorry for the ambiguity. The only locknuts associated with the rocker arms are for the valve clearance adjustment screws. To be obsessively technical just for the fun of it, it is the rocker arm that is being adjusted, not the valves. FWIW, I've done plenty of this type of adjustment by feel, and never had one come loose, but this is the first on a Guzzi for me. I suppose I'll dig out the service manual for my '57 Ford, which has a torque spec on various screw sizes and see what it says.

[Ryland3210]

OK, here is what I measured readjusting my rockers arms for the specified valve clearance:

Conditions: First time since the bike was purchased new.

As found:

Right cyl.: I .006, E .008 thou', Left cyl.: I .008, I .009

One nut loose on right cylinder at about 22 foot pounds, the rest OK.

After torqueing head:

Right cyl.: I .006, E .007 thou', Left cyl.: same as above, did not need to re-torque head

After adjusting clearance:

Right cyl.: I .004, E .006 thou', Left cyl.: I .004, I .006

 

Most interesting was the locknut torques to loosen were between 10 and 15 foot pounds. On tightening, I used 12. It felt all right by feel. It will be interesting to see how much, if any, that quiets things down.

[Guest ratchethack]

To be obsessively technical just for the fun of it, it is the rocker arm that is being adjusted, not the valves.

Well I reckon that technically, you may be correct, John -- but I doubt if you'll find too many who'd know wot you mean when you say you're adjusting your rockers arms.

 

I would argue that the critical dimension being adjusted is the "landing speed" (I'll bet Pete's got a better term for this) and seal pressure at the seat/valve face interface, and lash in operation is actually relatively unimportant at either end of the rocker -- or at the pushrod/follower or cam/follower interfaces.

 

The rockers are steel forgings with hardened steel adjusters and locknuts. They're over-engineered for strength. I reckon this is so that even the Luigis can't over-torque 'em after a grosso plate o' ravioli washed down with a few bottles o' chianti.

[Skeeve]

The rockers are steel forgings with hardened steel adjusters and locknuts. They're over-engineered for strength. I reckon this is so that even the Luigis can't over-torque 'em after a grosso plate o' ravioli washed down with a few bottles o' chianti.

 

Au contraire mon frere! The rockers are steel forgings w/ hardened bits etc. because anything less gets hammered to death in short order! And it's still rather simple to over torque small dia. screws like the locknuts mentioned. I'm certain somewhere amongst the threads on torque values, someone has already posted the guidelines to be used based on the base dia. of a threaded steel part; if not, it's prolly out there somewhere on the 'net.

[Guest ratchethack]

The rockers are steel forgings w/ hardened bits etc. because anything less gets hammered to death in short order!

Well of course you're correct, Skeeve. I reckon this is one of those situations where the synergy of more than one strength objective is served! As far as I'm concerned, the things are fairly tolerant of hand-torquing (for all but a ham-fisted Troglodyte!) -- although I seem to recall someone who encountered wot might've been a faulty rocker forging that failed at the adjuster end once. In any case, I'd be surprised to learn of any Pro who includes valve adjustments as part o' his livlihood who puts a torque wrench on 'em -- though there may actually be one somewhere.

 

BAA, TJM, & YMMV

[Ryland3210]

Well I reckon that technically, you may be correct, John -- but I doubt if you'll find too many who'd know wot you mean when you say you're adjusting your rockers arms.

 

I would argue that the critical dimension being adjusted is the "landing speed" (I'll bet Pete's got a better term for this) and seal pressure at the seat/valve face interface, and lash in operation is actually relatively unimportant at either end of the rocker -- or at the pushrod/follower or cam/follower interfaces.

 

The rockers are steel forgings with hardened steel adjusters and locknuts. They're over-engineered for strength. I reckon this is so that even the Luigis can't over-torque 'em after a grosso plate o' ravioli washed down with a few bottles o' chianti.

 

Valve lash or valve clearance are unambiguous terms that even accomodate adjustable pushrods on older engines.

 

My rockers are bronze, while the adjusting screws appear to be hardened steel. That's why I'm particularly careful about the tightening torque.

 

Good cam design certainly takes into account the deceleration of the valve (your term: "landing speed") at the end of the cycle, and, of course that is only ideal when the design clearance is achieved.

[Guest ratchethack]

My rockers are bronze, while the adjusting screws appear to be hardened steel.

YIKES! Bronze rockers??

 

Mine sure didn't LOOK like bronze when I had 'em out for head re-torque, but then I didn't do a magnet check, either. . .

 

I dinnae think so, me friend -- but I'm more'n willing to stand corrected, and await confirmation alongside my occasional Guzzi workshop companions, Mssrs. Shock and Awe. . .

 

I thought bronze rockers went out, well, somewhere around the end of the Bronze Age?!?!

 

Are you sure, John? Did you put a magnet on 'em??

[Ryland3210]

YIKES! Bronze rockers??

 

Mine sure didn't LOOK like bronze when I had 'em out for head re-torque, but then I didn't do a magnet check, either. . .

 

I dinnae think so, me friend -- but I'm more'n willing to stand corrected, and await confirmation alongside my occasional Guzzi workshop companions, Mssrs. Shock and Awe. . .

 

I thought bronze rockers went out, well, somewhere around the end of the Bronze Age?!?!

 

Are you sure, John? Did you put a magnet on 'em??

 

No, I did not test with a magnet, but I've never seen steel forgings look like bronze. My honda also had them. One advantage is the inherent wear resistance where it contacts the valve stem. As you probably know, sliding surfaces of dissimilar hardness materials resist galling as well.

[Guest ratchethack]

No, I did not test with a magnet, but I've never seen steel forgings look like bronze. My honda also had them. One advantage is the inherent wear resistance where it contacts the valve stem. As you probably know, sliding surfaces of dissimilar hardness materials resist galling as well.

Well, it was time for a valve adjustment so why not just now? I can see how you'd have thought they're bronze by the color, but they're forged steel, alright. The bronze colored coating on 'em is more'n likely part of the case hardening process, or part of how they're treated after quenching. Where's Pete? In any case, I b'lieve bronze forgings would have to be made prohibitively massive to match the strength of forged steel rockers. And of course excessive reciprocating mass in the valve train is a particularly egregious no-no.

[Skeeve]

Well, it was time for a valve adjustment so why not just now? I can see how you'd have thought they're bronze by the color, but they're forged steel, alright. The bronze colored coating on 'em is more'n likely part of the case hardening process, or part of how they're treated after quenching. Where's Pete? In any case, I b'lieve bronze forgings would have to be made prohibitively massive to match the strength of forged steel rockers. And of course excessive reciprocating mass in the valve train is a particularly egregious no-no.

 

The color is probably an electrolytic corrosion inhibitor that's applied after shot-peening intended to improve longevity: rockers have been known to fail, so most shops would keep at least one pair on hand on the shelf, possibly for years. That's my guess, & I'm sticking to it...

[Ryland3210]

 

The color is probably an electrolytic corrosion inhibitor that's applied after shot-peening intended to improve longevity: rockers have been known to fail, so most shops would keep at least one pair on hand on the shelf, possibly for years. That's my guess, & I'm sticking to it...

 

Sounds plausible, although I've seen plenty of other steel and cast iron parts in oil-bathed engines without corrosion protection that have not shown any sign of corrosion. As far as electrolytic action is concerned, the ends of the rockers are separated from the aluminum components by brass washers, so the aluminum is in contact with the relatively reactive brass in any event.

 

Anyway, I'm not sure we should clutter up a thread in the "how to" section with off-topic discussions any further. Next time I have the covers off, I will do a magnet test out of curiousity.