Timing belt vs. timing chain ?

for a "regular"car the timing chain is good for 100,000 miles, timing belt, 60,000

on a 308 the timing belt is good for 30,000 miles.

what is the lifespan of a timing chain on a 246 ?

what about a Colombo V12 ?

anyone ever considered converting the 308 to timing chains ?

 

Belts and chains both wear out. V6 Ferrari and Maserati 4 cam motors were notorious for wearing out cam drive parts including chains. Ferrari 4 cam V12 motors except for the Daytona had a 25,000 mile service interval on their chains.

The only real difference between chains and belts are that sitting in your garage the chains don't wear out, belts do. The price for that is that the chains are generally more expensive to replace.


Converting a 308 to chains would be costly and stupid. Belts just dont cost that much.

 

They are all are good until they break.
Designed loading, age, climate and contamination as well as how fast they run all influence their life. 30k intervals for an engine expected to be run hard is to your benefit given the cost of a failure.
Plenty of folks out there who've successfully run 'em longer in "regular" and F-cars.
Me, I'll gamble with a gently driven Toyota.

 

Brian - I respectfully disagree. While the belt issue in flat 12's is, in my opinion, way overdone, I have never seen a V6 (Dino) chain fail catastrophically.

Allow me to expand upon the belt issue. I frequent the flat-12 forum, owning a Boxer and a Testarossa. Non-engineers and those that purchase lottery tickets (a tax on those who do not know math) admonish people like me to change their belts every 15,000 miles or 5 years. I challenge these evangelicals by asking them to provide real examples of belt failure. Over the 8 years I have participated on F-Chat I believe that one example is real. There were 3,500 Boxers produced, and 13,000+ Testarossa and cousins. If belts were failing, we would hear about them. Of course, everyone who wishes to purchase a flat-12 hammers the seller for not having had the major performed (belt change = $10k). Thus, the folk-lore persists. Furthermore, my experience with 40 years of factory belts in two cars suggest that failure is infrequent. Upon replacement, both my belts looked like new.

At $10k per major every 5 years, I should have had 8 majors at a cost of $80k. An engine rebuild following a catastrophic failure is $30k. Thus, I can afford almost 3 non-contained failures and still be at least even, not to speak of the down-time associated with the major.

With all this background.....I challenge anyone to send me documentation of a chain failure in any Dino, Fiat or 246. There were 3,200 Dinos and some number of Fiats (don't know), but after 40 years of service, how many have failed?

Reynolds double link chains have been used in motorcycles since the 50s, and when rebuilding my Dino engines I, in fact, purchased Triumph motorcycle chain for the Dino at a cost of approximately $40 per bank. Still in there today. Chains don't fail. They stretch, slowly, predictably. Chain tensioner,,,,,enter stage left.

Thus, my choice for cam drive is chain. The reason Ferrari moved away from chain was noise. No other reason. And they ruined that beautiful sound of chaos and chain clanging that we all enjoy.

Jim S.

 

Please point out anywhere I said catastrophic?

I believe the term I used was "wear out".


How does that become catastrophic?

As for the rest I have grown very tired of arguing with those that have an experience of one car. Believe what you please.

 

I agree Jim, even BMW 6 Cylinder(single cam) get , and got by with a 'single row' Reynolds chain, and never saw either Alpina or Schnitzer replace to a double row chain and that cam was as long as a V12 cam.
Chains do stretch, sprockets wear, at which point you replace them. I have had FIAT belts fail, with the inevitable valve bend, but as you may imagine, not a mega dollar expense.

It is not a Ferrari isolated issue, and I do not think it is an issue of "single car experiences".
I think it is more an issue of fact and fiction. Statistics, real numbers, is the only gauge by which we can go by. If all Alfa Romeo head studs were to have failed, as everyone would have us believe, there would be 0 Alfas running around.

Same goes for Dino head studs.
How on earth did everyone survive without ARP? Sorry, ask 10 "expert " mechanics their pet peeves and you will get the full assortment. I go by what I am kindly advised, then draw my own conclusions, as opinions are more abundant than we'll ever know.
Were Corvairs really "unsafe at any speed"?
Perfection is relative. In F1, failures are abundant, and due to...

Remember the VW's that caught fire? Bottom line, an abundant lack of maintenance is also guilty of many issues, and that includes overtorquing Alfa heads with a torque wrench that cost $15.99 and had a pointer that went this way or that way.

Yet, we are bumping again.

So, to oblige the OP, all wear or longevity, it is relative to maintenance and usage, so no exact figures are available, except for the ones derived by calculated, lab controlled durability testing and no, I think converting a 308 to chains would imply incredibly high, and not a cost effective expenditure.

Regards, Alberto

 

I have suffered one chain related failure and one belt related failure. I say related because in either case, neither the belt nor the chain broke, in both cases, it was a idler bearing.

 

I have replaced plenty of dino 246 chains. They start to make noise as they wear out. I have never seen a broken chain. For that matter I have never seen a broken belt. The belt cars start to leak oil in and around the belt areas. The belt interval is also determined by oil leaks.

 

G'day Guys, Just been reading about timing chains and or timing belts in general for engines and thought I would throw my two cents in the ring.... I had a 1977 Alfa Romeo GTV Alfetta 2 litre car which used to get given a good workout as regular as clockwork and that engine had a duplex timing chain and I never had a problem with it what so ever.. When I retired that car ( due to rusted body ) it had 450,000 kilometers on it and I had never done anything to the motor apart from basic services and timing chain adjustment once a year. The engine was still pulling like a train even when I retired it. That was so simple to adjust, simply turn up the idle, then release the pinch bolt and the cam chain tensioner would tension the timing chain then tighten the bolt again. Use to take 10 minutes tops. I never thought the timing chain was noisy, just added to the charm of the engine purring. Then later, I bought a 1989 Porsche 928 s4 which had the timing belt. Well, I never had to worry about the Alfa Romeo Engine timing chain breaking and causing huge dollars of engine rebuild. But with the Porsche 928 S4 engine being an interference engine, it is always in the back of my mind that I must change it before a certain schedule or after so many years. Also, the timing belt drives the water pump and oil pump. As far as I am concerned give me a timing chain set up any time. I would rather have a little extra engine noise from a chain setup and not be worrying about a belt. The amount of times I have heard about timing belts breaking or losing teeth from the belt and causing major engine damage is a lot more than I have heard of timing chains breaking. I personally think they use timing belts to make more money in servicing. I note Lamborghini used a cam chain set up for their V12 engines and they put our phenomenal Horsepower. Cheers, John from Kapunda - Australia

 

As the chain stretches it gets noisy because it is not tensioned correctly. The Dino can be adjusted and all is good again. Badly adjusted chains wear out the slipper much quicker than the chain itself.