Too soft. They just dont hold up to the heat, load, RPM and minimal lubrication present in the 5V engines with the small stem diameters. What worked for large stem, lower RPM motors, using mildly effective teflon seals, doesnt with these screamers. Sinthered Steel guides. A PITA to machine and install, expensive as hell from Ferrari (BruceW bird dogged these years back but the opinion of the time was 'we dont need no stinkin steel guides', thus no reason for us to have them made affordably), but it is what works for the long haul. Ferrari knew that and needing to fix the problem before the 360 came out.... finally corrected it on the 355's, albeit years too late. Just dippin my toe in the water after coming up for air.... I miss many of this gang!
Have we actually observed failure of the manganese bronze guides that folks were installing years ago? A well known sponsor of this site had been recommending those guides.
I can have the above guides manufactured at a factory in Germany where I have a small % controlling interest now. This is the same factory where I have my 355/360/612/550/575/456 (348 soon too) water pumps tested and manufactured. I never thought much about having guides done as frankly I thought the market was flooded, but since there is only one manufacturer (whoever Ferrari farms them out to) and the cost is significant, I might make a run of them. I would need a sample of each intake/exhaust sinthered guide. Dave or anyone, if you have a couple I would gladly get to work on this and report back.
John, with your contributions, you are going to make this a better and more affordable car. Dave, are there any downsides to the steel guides? If and when they wear out, are they difficult to replace?
If someone can point me to which supplier might even have one of each I will gladly purchase a couple and go from there. I checked with Ted already and I know he doesn't have any, and I'm sure GT doesn't but am not completely sure regarding Ricambi, but I seem to recall asking a while back and getting a 'no'. I loathe calling the dealers for parts because a lot of the time they will be clueless regarding the material..... Regarding replacing them: Yeah they are a bear to replace on your own so just have a good machine shop that knows this type of head do it for you. A good shop normally charges about $5-$10 in labor for each guide + the cost of the guide of course. Sintered steel is a more porous metal (allowing from greater oil retention so I'm told) on top of being harder than any manganese so yeah, I would and I'm pretty sure anyone would prefer them over anything else. The manual way is to use the specific factory draft which features a nice guard so one doesn't accidentally whack the valve seat, but it still requires a hefty amount of whacking to get them out (or better yet, heat the head in an oven for a while, then whack) whereas a lot of machine shops just use an air hammer with an adapter and they come out pretty quick.
We do a lot of seal fit different materials with our scientific apparatus Ovens, nitrogen blast furnace, liquid nitrogen and dry ice are our friend. You would be amazed what removing 02 to fitting teenie tiney things together
Let's not get ahead of things here. Manganese Bronze is a generic name. Sintered steel is the name of a generic process. The hardness of manganese bronze depends on the alloy. 863 MB has a Rockwell B hardness of 95. What I could find on sintered steel said Rockwell B hardness was 87, but I have no idea what the alloy was or what the sintering process was. Just what the composition of the Ferrari sintered steel guides is, and at what temperature and pressure they are sintered at, will have a roll in determining what the hardness actually is, along with other lubricating, wear and thermal properties.
FYI check out the sintered steel options on this page: Metelli SpA | Production of the main components of the motor head: valve guides, valve seat inserts, valve shims and adjusting pads
I know Metelli as I have personal dealings with them. They make nice stuff but they certainly take their time (the Italian way right). I wouldn't be at all surprised if Ferrari use Metelli to make their guides as they are big and have made components for Ferrari in the past.
Thank You Sir! It is nothing short of a "Pinch Me" condition. In the last 45 years fixing these red sleds I have had dreams... those dreams paled to the reality I now walk into each morning. I OWNED the local Craigslist for the last year. The equipment I have stumbled into and obtained is mind numbing. I go to buy an electronics workbench that sells for 1800, and is advertised for 100... and end up buying (4) of them plus the entire Product Testing Lab's inventory for 3500. Next was an entire Eddie Bauer stores Walnut fixtures for 400... and it continued this way for a year. One of these days I will do a proper photo series when things are cleaned up and the rest of the boxes unloaded and put away. I am blessed that I have a bunch of local Ferrari owners who are retired and volunteer a day a week... just for the fun of it. Pinch Me doesn't begin to tell the story!
