I recently started taking metformin and after 4 months I can tighten my belt 2 more notches with the same tension. Those don't resemble the pulleys on my '85 QV. February 1985 build.
Fair point. I would have been more concerned if the new one was shorter. The old one being a bit shorter makes sense from what I know/learned about springs, there is a loss of spring formula that relates to stress relaxation depending on the material type, temp etc. so I was not surprised. I suppose I could have a slightly higher tension on the belt with the taller spring. I would expect that is why you just go by hand feel, and having done one belt change I would probably be fine to tension to a hand feel next time round as well.
Point being if you rely on the spring, new or old to get tension correct you do not know enough to be doing the job.
I honestly do not recall with any degree of certainty but I believe they were mostly 2 valve injected era.
I believe that "early" 308's had plastic pulleys, "later" cars used metal pulleys. My car is a OCT "77 build, it has plastic pulleys. As Windsock said, plastic cog with a metal center. The guide ring is also plastic, seemingly pressed on but I have found one ring with glue residue on it, factory or repair I don't know. No cracks on any of my pulleys, I checked them over carefully.
The belt change interval subject on all Ferrari's with cambelts has been done to death so much on Ferrarichat, that there should be an automatic re-direct to a site statement that simply says: "Change your cambelts when you feel most comfortable, and change your tensioner bearings too if you think they're needed" With cars such as the 348/F355/Mondial T/Testarossa series and other models where the cambelt change is very labour intensive, and expensive for those who do not work on their own cars, I can understand the thinking for extending the cambelt replacement service for as long as possible (especially looking at some of the prices Ferrari specialists seem to charge in the USA - UK specialists seem to charge a lot less!) With the 308/328/3.0/3.2Mondial cars, the cambelt replacement is a straight forward job, carried out with the engine in situ, through the rear wheel arch, and the parts are cheap. It's not even labour intensive (compare the work required to change the belts in a Ferrari 308/328 to a 1980's BMW, a VW or a Lancia Integrale! ) I change my belts and tensioners every 3 years (and I change my oil every year - With a new filter! , along with the air filter, fuel filter and coolant), because it's cheap as chips and gives me peace of mind (yes the tensioners probably don't need doing so often, but they don't add a massive amount to the bill) My thinking?: The cost of replacing the belts and tensioners is a damn sight cheaper than the cost of an engine rebuild due to a cambelt or tensioner failure! Each to their own - As I say though, the cost of a cambelt service on a 308/328 engine is hardly a bank breaker
No, not true at all. A gasket fits or not, bearing size and quality is easily determined. Most parts suitability is generally very easily determined by a knowledgeable mechanic by at the most, basic tools at hand. How many of you spent more than 8 seconds determining the suitability of the spring? And it does not begin to address my point. If the spring is all that you have to establish correct belt tension put the tools away and get it done by someone who has a clue.
Another thing to consider is that timing belts in automotive engines was relatively new technology at the time with the Boxer being the first production Ferrari utilizing them only a couple of years prior to the 308. Not yet proven in long term use and failures in any brand car would lead Ferrari (and other manufactures) to adopt a short replacement life recommendation out of an abundance of caution. Witness Ferrari's slow adaptation of disc brakes, they let others do the development and jumped in only after they were proven to be reliable long term. I would agree with 4rePhill, change the belts when you feel the need. Those of thus around at the time when timing belts were starting to appear on engines can remember that they were truly advanced technology. My cousin bought a Pontiac with their OHC 6 cylinder engine when it came out in 1966. He opened his hood constantly for people (gearheads in particular) to gaze in wonder at the strange arrangement at the front of the engine. The Fiat 124 followed shortly after, another engine with a prominent timing belt arrangement at the front. As a side note my son recently acquired a Fiat 124 spider from an estate in his wife's family. It had been sitting for 30 years and after prudent replacement of some components (timing belt included) and a carb rebuild the engine fired up at the first turn of the key. The engine was designed by ex-Ferrari engineer Lampredi, a wonderful little unit. Parts for the Fiat 124 are, in direct contrast to Ferrari, amazingly cheap rivaling the VW aircooled Bug in low cost.
I would add to stay away from SKF bearings (double race). Had them installed by a Ferrari dealer because that's what Ferrari recommended and when I went to do my own belts, the grease had flown out of the bearings and made a nice line around the inside of the covers. In addition, the bearings were noisy when I changed them. I use only Hill Engineering bearings now and have not had that experience since then.
Fiat used them far before Ferrari. Fiat owners in the USA did not take preventative changes seriously and they became famous for belt failures. It killed the Fiat market in the USA and they have never returned.
(PDF) DEVELOPMENT OF TIMING BELT DRIVES HISTORICAL DEVELOPMENT OF TIMING BELTS Timing belt is a relatively young drive, firstly designed as a drive for a sewing machine by engineer Richard Y. Case in 1946. It was a rubber belt with trapezoidal teeth profile. After twenty years, in 1962, the timing belt was for the first time built in an automobile, Glas 1004. Engine of Glas 1004 was the first engine where the timing belt was utilized as the camshaft drive (Synchroflex). Valve train was very simple and the timing belt drive had no belt tensioner, Figure 1. Massive use of the timing belts started at the end of 1960’s on Fiat 125 and Fiat 128 automobile and, at the beginning of 1970’s, on the first Golf automobile. After initial doubt, almost all producers of Otto and Diesel engines for passenger cars have utilized the timing belts. The timing belt is today the most frequently used camshaft drive. Application of the timing belts is mostly linked to automobiles, though just 2% of timing belt production is intended for application in automotive industry. Glas (company) - Wikipedia
