V7 II valve questions

[SportsterDoc]

Getting to the mileage to do mine.
Need to first pick up gaskets 887002 next trip to dealer ($2.72 each, last February) and get all the once-a-year garage sale (Oct 14) stuff out of the garage where I normally work..so I am only prepping.
Couple of questions, one of curiosity and one of practice:

1. Why are the measurements for a small block (0.006"/0.15 mm & 0.008"/.20 mm) so much more than a big block?   It must be related to heat expansion, of course, but do big blocks run much cooler?

2. If 0.006" on an intake is not snug, but 0.007 won't go, leave it alone, or close by ~1/2 a thou?

Using a stethoscope on the heads, the sounds seem no different than 7 months ago, so I am not expecting much, if any, change, other than I will let it sit for at least a day in the garage, before getting into it.  It is only 88 F in the garage this morning (was 100+ about a week ago) and should be under 80 F by mid October.

[guzzisteve]

Well, it goes back to 1981 update still stands, under 6 & 8 burns valves. The numbers change w/Guzzi management BUT the motor hasn't changed much since.
Much easier to make clearance perfect IF it has moved, you are in there.

[SportsterDoc]

Well, it goes back to 1981 update still stands, under 6 & 8 burns valves. The numbers change w/Guzzi management BUT the motor hasn't changed much since.

Most be allowance for a lot of heat expansion on the small block!

[SportsterDoc]

Much easier to make clearance perfect IF it has moved, you are in there.

Thanks for input Steve.
Will put my ancient P.K. Neuses gauges to work

[guzzisteve]

The III's may be different , too early to tell on different head design. Now there is a tunnel through the head for air.

[SportsterDoc]

Had a pleasant ride from Las Vegas, NV to Clarkdale, AZ, ~300 miles.
50 MPG from Kingman to Chino Valley, via Route 66.
Bit of a headwind coming down 89.
6500 miles on the clock.

Decided to go ahead and check the valves, since daughter has 3 1/2 car garage (more room than mine!)
With a jack on the right side of the frame and a block of wood under the side stand, easy to get rear wheel off ground.
Plan was to prep for a morning check/adjustment.

6 bolts on right valve cover broke loose easy and gasket came off in one piece.
After sitting for only 8 hours, the right side was spot on 0.006 and 0.008.
Might be more open, in the morning?

On the left side, 5 bolts broke loose easy, but the 6th would not budge.
Using a quality 1/4" drive Armstrong 5 mm bit, the bolt head rounded out (yes, the bit was full depth).
Too big a wallow to press in a Torx 30 and too small for a Torx 40.

Don't want to destroy the bolt, as the nearest dealer is probably Phoenix.

Said nuts and put it all back together.   Had the few tools needed in the bag under the seat, except for a #1 Phillips to align the gasket on re-assembly.

[pete roper]

Good trick if they are reluctant to move is give them a shock with a punch and hammer. This tends to loosen up any corrosion and they'll break free easier. Probably too late now its rounded out.

As for the allen bolt? Its a standard M6, 6x1 thread probably 20-25mm long. Should be available pretty much anywhere, even in the US.

Pete

[SportsterDoc]

Good trick if they are reluctant to move is give them a shock with a punch and hammer. This tends to loosen up any corrosion and they'll break free easier. Probably too late now its rounded out.

As for the allen bolt? Its a standard M6, 6x1 thread probably 20-25mm long. Should be available pretty much anywhere, even in the US.

If I were home, I would have used a breaker bar and taped on it with a hammer.
No corrosion issues (desert climate).

Son-in-law may have the M-6, but standard head...however, I only have one full day with the grandkids, tomorrow, so the left side will have to wait.   Probably have to drill off the bolt head and remove the remaining stud with visegrips.

Thanks for the advice/comments.

[redhawk47]

1. Why are the measurements for a small block (0.006"/0.15 mm & 0.008"/.20 mm) so much more than a big block?   It must be related to heat expansion, of course, but do big blocks run much cooler?

I don't know about older big blocks, but these are the specs for Stelvios also.

[pete roper]

8v will run better at 0.1 and 0.15. If using a Beetlemap they are all built for those lower clearances. With the 8V the gap increases with heat due to the CoE of the various parts.

Pete

[beetle]

The original specs for the 8V were 0.1/0.15. During the early days of the flat tappet fiasco, Guzzi changed it to 0.15/0.2.

Actually, there's some weird values in some of the service manuals. 2010 Stelvio had 0.1/0.2 clearances.

[pete roper]

My thoughts were always that this was gratuitous straw grasping.

My own experimentation has confirmed that on most Guzzi engines post roundfin big blocks the clearance on valves opens up as the parts reach operating temperature. If you look at the materials involved in the componentry it's obvious why but most people don't. They just recite the mantra that clearances close up with heat without actually thinking about it holistically, (Or methinks having much of an idea about the laws of physics!) but that's life......

Pete

[randy yocum]

 

That could be easily verified by checking clearances while the engine is hot, one could expect the gap to have increased,is that right? just asking,you may need some asbestos gloves though.

[pete roper]

No need for asbestos gloves, speed is of the essence though. Simply prepare the bike by removing any extraneous crap that interferes with the removal of the rocker covers and go for a ride long enough to get the engine hot.

Once back in the workshop leave the bike idling until you are absolutely ready to dive in and have your tools to pull the rocker cover and check the clearances to hand.

Kill the engine, whip off the HT lead, remove the rocker cover and turn the crank to TDC compression and jam a feeler guage into the gap. I can gaurantee you you'll be able to go up at least 2 thou on any big block, post roundfin, motor. Smallblocks are more sensitive and the *Growth* is less due to the rocker design, (Herron head.) with the V9's and their derivatives I'd be expecting a return to greater growth due to the rocker carrier design. The whole check, after the warm up ride, will take 2 minutes a side. You don't have to take my word for it.

Yes, you will need gloves or a piece of cloth to remove the hot rocker cover but not asbestos! Really, the rocker covers don't get that hot in normal service. REALLY!

Pete

[randy yocum]

That's really good to know,I've been riding and wrenching 40 years and always increased valve clearances a smidgen on my air cooled engines during the hot summer riding season, just to err on the side of caution .I don't mind the sound of a clanking valve train,preferring that to burnt valves ,it's when the top end is too quiet that I start to worry.

[beetle]

My thoughts were always that this was gratuitous straw grasping.

Maybe it was! Curiously, the values in the service manuals changed in the 2011 releases. Prior to that, they were 0.1/0.15, then suddenly 0.1/0.2, or 0.15/0.2.

The 2009 Stelvio NTX SM even goes this far:

[Zinfan]

  Probably have to drill off the bolt head and remove the remaining stud with visegrips.

When I had some round out I got them out by using a dremel to cut a slot in the bolt head and then tapping a chisel against the slot (I tried using a screwdriver into the slot but that didn't work at all).