Valve Adjustment Specs

[Guest ratchethack]

Next time I have the covers off, I will do a magnet test out of curiousity.

FWIW, my magnet test at the valve adjust noted above showed significant ferrous content, exactly wot I expect from steel.

 

BAA, TJM, but I doubt with considerable conviction that y'er M is gonna V.

[Pierre]

I'm amazed two such disparate sets of numbers have been posted, and no one has tried to resolve the differences. The difference between two thousandths and one-hundred thousandths would seem to me significant.

 

In the workshop manual for the sport i (page 7) recommended settings (cold) are:

 

i = .10

e = .15

 

Those same numbers are repeated on page 58, with an added dimension listed on that page for "USA version." That setting (USA version) is listed as:

 

i = .05

e = .05

 

Mike Rich has given me different settings, but they are for use with titanium push rods - presumably stiffer The settings Mike gave me for use with his titanium push rods were:

 

i = .002

e = .004 to .006

 

So you have a newbie on here who asks for settings and has gotten two substantially different sets of numbers in response. Meanwhile y'all have gone off to discuss the color / coating / composition of the rocker arms.

 

Anyone know how to reconcile the two sets of numbers - except based upon the relatively greater stiffness of the after market push rod? It sure looks like the i = .10 and e = .15 are factory recommended settings going back at least as far as the sport i version.

[Guest ratchethack]

I'm amazed two such disparate sets of numbers have been posted, and no one has tried to resolve the differences. The difference between two thousandths and one-hundred thousandths would seem to me significant.

. . .

Anyone know how to reconcile the two sets of numbers - except based upon the relatively greater stiffness of the after market push rod? It sure looks like the i = .10 and e = .15 are factory recommended settings going back at least as far as the sport i version.

Pierre, the large variance you cite above is the difference between a spec in mm and a spec in inches.

[BrianG]

I'm amazed two such disparate sets of numbers have been posted, and no one has tried to resolve the differences. The difference between two thousandths and one-hundred thousandths would seem to me significant.

 

In the workshop manual for the sport i (page 7) recommended settings (cold) are:

 

i = .10

e = .15

 

Those same numbers are repeated on page 58, with an added dimension listed on that page for "USA version." That setting (USA version) is listed as:

 

i = .05

e = .05

 

Mike Rich has given me different settings, but they are for use with titanium push rods - presumably stiffer The settings Mike gave me for use with his titanium push rods were:

 

i = .002

e = .004 to .006

 

So you have a newbie on here who asks for settings and has gotten two substantially different sets of numbers in response. Meanwhile y'all have gone off to discuss the color / coating / composition of the rocker arms.

 

Anyone know how to reconcile the two sets of numbers - except based upon the relatively greater stiffness of the after market push rod? It sure looks like the i = .10 and e = .15 are factory recommended settings going back at least as far as the sport i version.

 

I'll throw in a casual observation in answer to your query Pierre....

 

With some 40 yrs of experience messing with internal combustion engines and hotrodding everything I could find from flatheads to EFI controlled DOHC Porsches, it is my observation that valve lash clearances hover right around 0.006/0.008 int/exh on most all solid lifter, pushrod engines.

 

Tighter clearances is either a noise abatement strategy, or an attempt to get more high RPM performance out of a lesser cam. Looser clearances are noisy but sometimes used to get street-drivability out of an engine that was cammed very hot for the track, but the driver wanted to roll the streets for a bit of show-off.

 

Our donk is a military truck engine..... 0.006/0.008 should be perfect. If the noise bugs you, 0.004/0.006 will be ok. Tighter than that will give you idling trouble and might scorch exhaust valves. Much looser than that and you are going to start losing top end performance.

[Guest ratchethack]

0.006/0.008 should be perfect.

This is wot I've been using for years. It seems to be better than 0.004/0.006 for warmish climates such as me own, especially in temps around 100F (38C).

 

Oddly enough (or not? ), last time around, all were nearly spot-on at 6 K mi since last adjustment save the LHS exhaust, which had tightened up by 0.001.

[Pierre]

Pierre, the large variance you cite above is the difference between a spec in mm and a spec in inches.

You're right, Hack.

 

Mea culpa, all.

 

FWIW - the Mike Rich numbers I cited were also in inches.

[BrianG]

This is wot I've been using for years. It seems to be better than 0.004/0.006 for warmish climates such as me own, especially in temps around 100F (38C).

 

Oddly enough (or not? ), last time around, all were nearly spot-on at 6 K mi since last adjustment save the LHS exhaust, which had tightened up by 0.001.

 

I don't know whether you realize it or not, but here's one for ya~!

 

Of course valve train parts wear would lead to a loosening of the lash settings which is what happens in ironhead engines.... did ya know that the tightening on our engines is because valve action is actually pounding the valve seats up into the aluminum head casting?

[Ryland3210]

I don't know whether you realize it or not, but here's one for ya~!

 

Of course valve train parts wear would lead to a loosening of the lash settings which is what happens in ironhead engines.... did ya know that the tightening on our engines is because valve action is actually pounding the valve seats up into the aluminum head casting?

 

What's the basis for that? I find it improbable that the aluminum head casting would yield in compression. However, I am less skeptical that wear of the valve seat and valve itself would reduce valve lash. I too have decades of experience rebuilding and maintaining engines, and have seen that happen. However, arguments from authority are less reliable than science, and I'm always willing to learn.

[Guest ratchethack]

I don't know whether you realize it or not, but here's one for ya~!

 

Of course valve train parts wear would lead to a loosening of the lash settings which is what happens in ironhead engines.... did ya know that the tightening on our engines is because valve action is actually pounding the valve seats up into the aluminum head casting?

I did not know that, but I s'pose it makes sense. I did know that the aluminum heads have iron alloy seat inserts that are typically the hardest metal on an engine, and in ultra-high mileage motors the seats can work loose. The wear at the valve/seat interface is typically all on the valve face.

[dlaing]

At my last valve adjustment the left exhaust had tightened the rocker freeplay to a little less than 0.05mm.

Should something be done when the valves tighten up that much?

Obviously one should re-adjust the rocker.

But is it an indication that one might need new seats or new valves?

At 40,000 miles I imagine my valve stems are pretty worn, so it is probably time to replace.

The last five valve adjustments it MAY have tightened up maybe 0.04, 0.01, 0.02, 0.03 and now 0.15 totalling 0.25mm.

Can we assume that the valve seat recessed and wore nearly 0.25mm?

I guess a compression test is in order.

EDIT compression tested OK 135PSI Left and 140PSI Right on a slightly warmed up engine. I should do a better reading with engine hot. I suppose I should be getting more like 150PSI, but I am relieved that I don't have a big right to left difference. Adding oil boosted both cylinders 5PSI. Maybe it will need new rings soon. Oil consumption could be better.

I can only assume that when hot I had no rocker freeplay, and the valve may be cracked from overheating

When I started getting variable idle speeds I reset TPS and TBs and the problem continued, but I should have checked the tappet clearance immediately upon discovering the half tuneup did not fix it.

Mea maxima culpa

 

The wear at the valve/seat interface is typically all on the valve face.

Oh, OK that makes me feel better

[pete roper]

Thing is both valve clearances closing up and opening up between servicing is quite possible.

 

If they close up it will be because the valve is hammering into the seat, I dunno about the seat being hammered into the head? It isn't something that had occured to me but seats do come loose and to do that there would have to be some sort of wear so I don't see it as an unlikely scenario. Also the neck of the valve can stretch in service, especially if the springs are set up with too much preload or the engine is run lean. Smallblock Guzzis are prone to this, especially the 4 valvers. It is VITAL with them to check your clearances every 3,000 miles and the moment they beggin to close up appreciably its time to swap out the valves. This usually occurs at about 35-40,000 miles. Ignoring it leads to the exhaust valves shedding their heads with, errr, ugly results.

 

If they open up it will be due to wear on parts like the rocker spindles and bushes and possibly cam followers. Also if the pushrods start to collapse this will open up the clearances radically.

 

Choice of clearance and the range of clearances specified by the factory is always a bone of contention. If you look at the valvetrain of the big blocks NOTHING has really changed since 1967 apart from the rocker carrier material having been changed from cast iron to aluminium alloy when the squarefin motor was launched. Apart from that there are still chilled cast iron cam followers, alloy pushrods etc.

 

It is my belief that the early specs for valve clearance on the Roundfin bikes of 8 thou inlet and exhaust were chosen because the bikes were designed for use by the police and military. This meant that they expected long periods of idling without much cooling air flow and the *servicing* would be undertaken by snotty conscripts and the sort of mechanical marvels who could only get employment working for the Caribiniere! . For everyday use I find these far too large and a major contributor to the 'Two cheesgraters fornicating in an iron tank' rattle that roundfins are famous for! I personally run my roundies at 5 and 7 thou in the summer and 4 and 6 in the winter. I've even gone tighter than that with no problems.

 

With the squarefins with alloy rocker carriers which will expand more with heat the clearances can be set even tighter if you wish but I personally see no point. The 'US' specs of 2 and 4 thou were supposedly specified to help reduce noise and are *very* tight. Having said that I've never heard of anyone burning a valve with those settings but I HAVE heard of people having idling problems after a good thrash on a hot day! 4 and 6, the 'World' specs seem to work fine with the stock valvetrain. Why change something that works?

 

On our racebike we run ChroMo pushrods and these are set to 2 thou inlet and exhaust, cold, regardless of cam profile. That seems to work well. As for Titanium pushrods? Wouldn't know. Horrible stuff Titanium, apart from cosmetics I wouldn't want any of it anywhere near my engine!

 

Pete

[Pierre]

On our racebike we run ChroMo pushrods and these are set to 2 thou inlet and exhaust, cold, regardless of cam profile. That seems to work well. As for Titanium pushrods? Wouldn't know. Horrible stuff Titanium, apart from cosmetics I wouldn't want any of it anywhere near my engine!

 

Pete

Pete, once again you mercilessly trash my upgrade choice. First it was Bernd's timing gears and now Mike Rich's titanium push rods. Is it me? I'm beginning to think I need to publish my choices anonymously to avoid having the vendors I use get the sharp end of your stick merely for selling to me.

 

Titanium is light and stiff - both good qualities I would think for long hollow tubes going up and down rapidly - especially with a relatively radical cam.

 

Chrome moly (Raceco?) is very stiff, but very heavy from what I've been told.

 

YM apparently does V

[BrianG]

What's the basis for that? I find it improbable that the aluminum head casting would yield in compression. However, I am less skeptical that wear of the valve seat and valve itself would reduce valve lash. I too have decades of experience rebuilding and maintaining engines, and have seen that happen. However, arguments from authority are less reliable than science, and I'm always willing to learn.

My comment wasn't specifically about the MG engine's head, but about aluminum heads in general. The valve seat is typically an alloy called "stellite" which is very very hard. I have measured ingress of these seats in some instances and, as ratchet pointed out, they are known to loosen, due to impact, occasionally.

[pete roper]

Pete, once again you mercilessly trash my upgrade choice. First it was Bernd's timing gears and now Mike Rich's titanium push rods. Is it me? I'm beginning to think I need to publish my choices anonymously to avoid having the vendors I use get the sharp end of your stick merely for selling to me.

 

Titanium is light and stiff - both good qualities I would think for long hollow tubes going up and down rapidly - especially with a relatively radical cam.

 

Chrome moly (Raceco?) is very stiff, but very heavy from what I've been told.

 

YM apparently does V

 

Titanium IS both light and stiff. Unfortunately it also has a lousy fatigue life. Doubt me? By all means, but go and look at the service intervals for Titanium con-rods on the Arrow, (Yup, FI cars.) site and be horrified! OK, so the pushrods will operate in compression rather than extension stress but even so......

 

On the timing gear thing. (sigh.) I bought a set of supposedly super-brilliant timing gears from SD. Why? because I too think that *THEORETICALLY* gears have advantages. These were a set of relatively fine spline gears with a steel crank gear and alloy for the cam and pump gears.

 

1.) They were, from new, incredibly noisy despite being helically cut.

 

2.) A few months after I installed mine a bloke posted on Phil's board that he's had a set of identical gears fail catastrophically in his bike. Because of this I decided to have a squizz at mine and despite them being installed in a bog-stock SP, (Scarcely a warp speed hot-rod!) the alloy gears were showing what TO ME looked like unacceptable wear and brinneling of the teeth, so I took them out and re-fitted a chain and tensioner.

 

3.) It has been suggested that I don't 'Know how to' install gears. Look, it's a f@cking wheel on the end of a stick! Lots of people who should know better suggest that the torque of the nut is critical. Bullshit! The nut has to be tight enough to impart the friction between the end face of the camshaft and the back of the gear to drive it without shearing the peg. The only other suggestion for torque setting on fitment is that if you over-torque it the gear is going to deform and hash-up the tooth mesh. Errrr....Hello????? Are they REALLY suggesting that a material that would deform that much in compression is going to be strong enough to take the extreme loadings imparted by the accelerative forces of the valve train as the follower comes off the cam ramping????? I don't HAVE to do the math! It's bullshit! It would be like making a road grader blade out of plasticene!

 

As I've said MANY times before but am consistently ignored over I think that the IDEA of gears, especially fully vernierable ones, is GREAT. Both our race bike and Steve Harney's have gears. Helically cut, fully vernierable steel gear sets that ensure precise valve timing with bloody good adjustability. The problem is that in MY EXPERIENCE none of the currently available sets meet my criteria of offering reliability and a gauranteed long service life. There are MANY people riding high milage Guzzis with gear sets in from a variety of manufacturers. I'm ecstatic for them ! If they're happy that is FINE. I have just seen so many sets fail that I refuse to fit them. That is ALL I'm saying.

 

There is also the issue of necessity! Many, many people don't do enough distance on their bikes to ever need to worry about swapping a chain. Also many, many people don't want to run incredibly radical cams in their bikes and unless you are you are HIGHLY UNLIKELY to EVER notice the difference between a chain driven and a gear driven timing system!

 

I really, really hope that this doesn't decend into yet another ill informed rant by inexperienced theoreticians about how stupid I am because I really couldn't give the tiniest of f@cks what other people think. This isn't a go at you Piere, but do PLEASE give some thought to what you are actually trying to achive, why and how much it will cost!

 

To go back to my other, usual, bug-bear. Spend the money on SUSPENSION, not the bloody MOTOR. You REALLY, REALLY WON'T REGRET IT!!!!

 

Pete

[Skeeve]

Titanium IS both light and stiff. Unfortunately it also has a lousy fatigue life.

 

Carbon fiber is even lighter & stiffer! Unfortunately, epoxy doesn't like extended exposure to hot solvents, & you really, really wouldn't want stray bits of CF floating around the engine scoring things...

 

Seems like aluminum or steel pushrods are it for awhile; what would work much better would be nice fat thinwall hollow tubes to be stiffer yet lighter, but there're space constraints on that approach. Guess we'll just have to get by w/ what we already have...

 

On the timing gear thing. (sigh.) I bought a set of supposedly super-brilliant timing gears from SD. Why? because I too think that *THEORETICALLY* gears have advantages. These were a set of relatively fine spline gears with a steel crank gear and alloy for the cam and pump gears.

 

1.) They were, from new, incredibly noisy despite being helically cut.

 

2.) A few months after I installed mine a bloke posted on Phil's board that he's had a set of identical gears fail catastrophically in his bike. Because of this I decided to have a squizz at mine and despite them being installed in a bog-stock SP, (Scarcely a warp speed hot-rod!) the alloy gears were showing what TO ME looked like unacceptable wear and brinneling of the teeth, so I took them out and re-fitted a chain and tensioner.

 

 

That's something that gets me every time I read it: where's the thrust washer to take up all the end forces these helical gears are putting into the cam, crank & oil pump? Yeah, o.k., so helical gears are quieter than straight spurs, but the added friction and end thrust certainly makes a simpler approach worth looking into, doesn't it? Why am I the only one thinking about this? And Pete, if you're done w/ those gears, can I have'em? I need diametral pitch measurements &etc if I'm ever going to figure out how to make some straight gears on my hobby lathe [don't worry, I won't make'em out of aluminum: that's the stupidest thing I've ever heard! These aren't sewing machines or computer plotters, they're IC engines w/ big honking pistons! It's all brass for me, at least until I get the kinks worked out... ]

 

3.) It has been suggested that I don't 'Know how to' install gears. Look, it's a f@cking wheel on the end of a stick! Lots of people who should know better suggest that the torque of the nut is critical.

 

Heh. Now Pete, how tightly the nut who criticized your gear-installing abilities has his tinfoil hat torqued down is vitally important, don't you doubt it! Since I hear most often of bolts failing when trying to undo the from-factory torqued bolts on car cams, I suspect that "just about as torqued as you can get'em" is probably the right amount, but I'll defer to your far greater experience if that's alright w/ you...

 

As I've said MANY times before but am consistently ignored over I think that the IDEA of gears, especially fully vernierable ones, is GREAT. Both our race bike and Steve Harney's have gears. Helically cut, fully vernierable steel gear sets that ensure precise valve timing with bloody good adjustability. The problem is that in MY EXPERIENCE none of the currently available sets meet my criteria of offering reliability and a gauranteed long service life. There are MANY people riding high milage Guzzis with gear sets in from a variety of manufacturers. I'm ecstatic for them ! If they're happy that is FINE. I have just seen so many sets fail that I refuse to fit them. That is ALL I'm saying.

 

There is also the issue of necessity! Many, many people don't do enough distance on their bikes to ever need to worry about swapping a chain. Also many, many people don't want to run incredibly radical cams in their bikes and unless you are you are HIGHLY UNLIKELY to EVER notice the difference between a chain driven and a gear driven timing system!

...

Pete

 

Yeah, I think that many of the people who're hot on the idea of gear-driven cams are that way because that's what the original V700, Ambassador, Telai Rossos, etc. had & hence if Guzzis were supposed to come w/ chain-driven cams then that's the way that God & Giulio Carcano would have made them. What they're forgetting in that reasoning is that Carcano & Umberto Todero with him [& Lino Tonti after Carcano] were all engineers w/ their background in racing! So of course their 1st iteration of a motor is going to have gear driven cams: nothing else likely even occurred to them! Down the road, the production engineering gets done & whaddaya know, chain-drive just make more [dollars &] sense. Doesn't mean it can't work as well or even better for 99.9% of the riders out there, just that it wasn't their first choice as engineers firmly committed to racing anything they could. [& good for us that they were that way, God bless'em, or we probably wouldn't like our Guzzis half so much!]