Questions on timing chains vs. timing belts, TIA.

Just to be clear: the Lotus Twin Cam has a modified Ford block, but has avoided any problems the Ford version may have had with tensioner slippage. As I said, I have no knowledge of any Lotus TC engine ever slipping a tooth/breaking a chain, etc. Perhaps the design was improved?

Ken

 

I guess you weren't around when they came out.

 

F50 was a race based engine. They didn't care what costs were (as opposed to 308, 360, 550. Sorry you are wrong on that one too. Ferrari is as cost concious as Honda). They did not care what it might cost in the event of failure, HP production was the goal, period.

And if you are still thinking 3/8 pitch double roller Reynolds chains, forget it, those should have gone out in the 50's. Modern chain designs and drives have nothing in common with those save the material they are made of. Weight and HP loss are very small compared to those old systems and the benefits far outweigh those small penalties. After a few hours of running, a chain drive motor still maintains correct valve timing, something a belt cannot do with the accuracy needed for a race motor.

 

Bill, install new belts and tensioner bearings and start enjoying!

The only thing that should scare you, is me screaming at you on the radio to buy your next F-150 supercab from Scaffidi Truck Center Stevens Point!

 

I have performed 2 engine-outs on my Testarossa, and I replaced the timing belts and tensioners both times, along with a water pump rebuild and some seals. I used to live in fear of belt breakage as has been mentioned. But over time I've become comfortable with it and even "forget about it" sometimes. I drive my car with spirit....hitting some major rpms occasionally and all is fine. If changed at a reasonable interval....belts are FINE !!! If there is oil or some other fluid getting to the belts, or maybe some debris, then you DO HAVE REASON TO WORRY!! Yes...belts do stretch slightly trying to find their "set" point, but once there all is good and they are very very close to chains in accuracy. Chain systems add weight, occasionally noise, and need lubrication. Belts are better in each of these areas. The only thing belts have against them is the fear of breakage. No way around it. But after almost 5 happy years of ownership and many miles of fun driving I've come to accept belts.....I don't loose any sleep over them anymore. Yes a crankshaft spins very fast at 6000 rpms, but the cams only spin at half that speed, the belts aren't flailing about like a fish out of water in there at these times. All is in control. If there was a fundimental flaw in using belts then they would have been done away with by now. A catastrophic event can happen any time with belts or chaines....if you do your maintenance properly......the odds are you wont' have a problem. This is just my 2 cents worth and I'll give a penny back......

 

Very wise and enlightened responce dude. Makes alot of sense

 

So your going to try and tell us that Ferrari, being if not the first, one of the first to use belt driven cams on a Formula One engine, did it only to save costs? And the F-40 the same idea? I am sorry but I humbly disagree. They were already building chain driven V-12 engines, so it couldnt have been much of a pinch to make a chain driven flat 12. And I have absolutely no doubt, that if the F-50 had belt drive cams, it would out walk its chain driven brother, all else being equal. If a chain over a belt dont matter, why would a lightened flywheel?

 

Well hey if you wanna go that far, then let's just ditch the belts and chains all together. If we are gonna compair apples to watermelons, lets through in mangos while we're at it. BRING ON THE GEAR DRIVES. After all that's what they use in the F1 engines these days, and the f1 engines rev WAY higher than any other engine on the planet short of a turbine engine. They don't loose timing, are good for 19,000+ rpm, and NEVER have to be changed.

I would also like to say that, I am SOOOO happy Ferrari did away with the belt and went with the CHAIN for the Brand New F430. And that engine revs just as high as the rest of the bunch. The biggest thing in favor of chains is VERY LOW up keep = cheaper to own in the long run.

One more tid bit. My 348 uses a timing chain. Were you ask? It comes off of the crank shaft and runs the pully for the timing belt.

Looks like the chain wins again.

 

Well, I was very young! The Lotus twincam came out in the early 60's with the Coverntry Climax engine (I think). It was on the Ford Cortina and that engine needed a complete rebuild every 30k miles. It was a race engine and poorly suited for a street car even though it was a good performer for the era on a "family" sports sedan. I wouldn't be surprised if timing chains were an issue on these since EVERYTHING was an issue on these.

The "modern" Lotus TC engine came along after that; distinguished in part with a modern spin on oil filter. They were in the Elans of the 60's and made it into the Europa in 1971. They were discontinued in 1975; replaced by the 907 engine that was in Jensen Healy's and the first generation Esprit.

Ken

 

Just change your belts and move on - it's not a big deal. If a 3x8 had chains some people would find something else to complain about. Besides, getting a little oil/grease on your hands is a great break from the day to day reality of the real world.

 

I couldn't have said it better. IMHO, the type of belt used on the 3X8 (square tooth) is much more of an issue than belt vs chain. The length of the belt or chain is also a determining factor. Those high milage American V8 chains are about 18" to 22" in length and turn relatively slow around larger diameter sprockets. My 180K mile small block Chev van engine's chain probably flaps like a flag in the wind and someday it will strip a sprocket or break in half. If it were the length of a 3X8 belt the accumulated stretch would have done the engine in long ago.
Any self respecting gear head can change out 3X8 belts on a Saturday morning and not have to worry about missing lunch. You can't do that on many Hondas or Toyotas.

 

Somebody buy this man a beer, I couldnt have said that better if i tried. And I have tried.

 

Is it really that easy? I assume the cam timing is the only tricky part? Or can you lock it all tight and not even worry about that?

Ken

 

I think its pretty easy. I never worked on a Ferrari before I bought mine, but I have been working on engines all my life. When I brought my car home, the first thing I did was a basic 30K service on the engine to see what I had. I didn't really go after it to time myself, but it didnt take me all day to tear it apart. If I had just put on new belts and put it all back together, I think I could easily have done it all in about 5 or six hours.

 

Slightly OT: Nissan/Infiniti is moving away from timing belts. The last timing belt engine from Nissan that I recall is the VG-series of engines in the 300ZX and X-Terra.

Hell, my 1994 Sentra SE-R uses a timing chain.

///Michael.

 

I would agree with Paul on this. I have done several belt changes over the years. They are fairly simple to do. I will need to do my 355 this winter and I am actually looking forward to it. There is a little more time involved becuase the engine needs to come out, a fun challenge IMO. Regards, Vern

 

Don't want to venture too far off topic.....but I LOVE THIS CAR. I had a 96 200 SE-R that was so much damn fun to drive and easy to mod - ZERO maintenance but fluids. Knew a guy with some Stillen and JWT stuff that got near 400HP. MAN I miss that car.....rear-ended in traffic a couple of years ago.