A couple of things I've noticed since I joined the Pavoni lever world back in summer 2012...

1) The group needs to come off fairly frequently for cleaning/service, and that's a little worrisome because repeated threading and unthreading of steel bolts slowly weakens the brass you screw into.

2) Making matters worse, Robert/rpavlis pointed out that in some cases, the group bolts they give you are not as long as they can be, so they don't go as deep as the could, thereby putting undue stress on the first threads of the boiler boss.

I solved the second one years ago, by getting longer bolts, in stainless steel, with Allen heads for easier removal/installation. I have a fair few pictures of that setup floating around the lever forum here. Last summer though, I finally addressed the first issue, by getting some stainless steel studs and threading them into the boiler... where they stay threaded, reducing repetitive wear on the boiler threads, so the only thing that comes off is the stainless steel nuts/washers. If this is of interest to others, the studs are from ARP, in M6-1 thread pitch. You should determine the length you need/want, so that the studs reach in deep or to the bottom. Here is a pic of mine:



-Peter

The big advantage of stainless studs is that they do not wear much. They are also easier to remove and replace during servicing. One of my La Pavonis has studs like this, the other brass bolts that I cut so that they just get to the bottom of the bore. (An easy and inexpensive way to get stainless steel studs is to decapitate a stainless steel bolt to the correct length.) Should you want to remove studs like this, it is easy to put two M6x1.0 nuts on the stud, and turn the inner one with a tool, as one keeps turning the nut, the stud will generally come right out as the inner nut locks against the outer one.

rpavlis wrote:An easy and inexpensive way to get stainless steel studs is to decapitate a stainless steel bolt to the correct length.

ARP stainless studs in that size list for about $20 a pair with washers and nuts. They're probably listed as accessory studs of some kind (valve cover? alternator?) and are much nicer than a cut down bolt. Call an ARP dealer like Summit Racing or Speedway with the size to find out which ones to order.

If you choose to cut bolts, I recommend using bolts with thread length equal to the depth of the hole and a solid shoulder between the threads and the head. Cut through the un-threaded shank and try to round off the cut end - you can file and grind it until the cows come home, but you won't be able to make it perfect. The nut will go on much easier over a rounded shank than it will if you cut through the threads, because the cut thread lends itself to cross-threading.

bluesman wrote:ARP stainless studs in that size list for about $20 a pair with washers and nuts. They're probably listed as accessory studs of some kind (valve cover? alternator?) and are much nicer than a cut down bolt. Call an ARP dealer like Summit Racing or Speedway with the size to find out which ones to order.

http://www.allensfasteners.com/detail.a ... B1.312-12G

These ^^^ are the ones I used, and were _exactly_ the right depth: $4.61 each. I got four, (for my two Europiccolas), for $6 shipping. The ss nuts and washers were about a buck total at the local hardware store. As you can see, the studs have an unthreaded portion right where the group flange sits. Not a big deal in such a low stress environment, but still a nice professional touch.

I have a huge account with Summit from building my racing engines, but unless you have an order for $100 or more, the shipping is more expensive than Allen Fasteners. Also, Allen fasteners is a favored business among local race engine builders (boat and car) in the southwest. In Santa Barbara, I'm only 20 miles or so from ARP headquarters where they have a will call window so I can buy direct... but the round trip time, gas and wear and tear on a car wasn't worth the $6 shipping.

-Peter

pcrussell50 wrote:http://www.allensfasteners.com/detail.a ... B1.312-12G

These ^^^ are the ones I used, and were _exactly_ the right depth: $4.61 each.

Cool! I've never used Allen's products, but they look like a good bet. I've gotten most of my hardware & raw materials from the Dillsburg Aeroplane Works near Lancaster, PA - sheet and bar stock, DOM tubing, Gr 8 and AN fasteners, rod ends, spherical bearings, etc - they have a huge variety of wonderful stuff in ordinary and exotic materials. I'm a life-long SCCA racer (FV Zink C4, C-sedan 1275 Cooper S, and an H-mod LeGrand Mk 3 with a Saab Monte Carlo engine) and builder. Thanks for the tip!

I've never shopped with Dillsburg, but I know well of them. One of my aero engineering* professors in college shopped there for his homebuilt aircraft needs... That and Aircraft Spruce. I had forgotten about Dillsburg in the 24 years since I graduated. But you have put them back on my radar.

Love to rig up some bearings for the lever bushings. But I'm not a machinist (or any kind of fabricator). So I make do with a wee dab of high film strength grease (ARP assembly lube, which I have plenty of).

*I was actually an ME major, with special permission to take some elective AE courses

-Peter

If the studs were sized just right, could acorn nuts be used instead of a hex nut for esthetic purposes instead ?

I have acorn nuts on the 1978 La Pavoni on which I put studs. Fortunately the threads on the La Pavoni are M6x1.0, the most common M6 thread pitch. You can get them in stainless and (harder to find) brass. (By the way, the brass ones can be easily drilled to make one hole steam tips for La Pavoni machines because the La Pavoni steam tips are also M6x1.0.)

Hi there. I like the look and idea of these studs. Much better than the too-short bolts that come with the pavoni. Question though. Since the studs are simply threaded into the boiler body, then the group head attached and the nuts threaded on, when you go to unscrew the nuts don't you still have the probability that the entire stud will unscrew, not just the nut?