As some of you well know, I'm tearing my Mini down to the bare shell and as such, I'm thinking ahead on every possible modification that I might want and whether I want to do it. Another one that I'd like to seek advice from some of you is a belt-drive conversion for the timing belt.

I've heard that in addition to being more precise than a simplex/duplex chain setup, it's also quieter. Since this mod is not exactly the cheapest of mods, I wanted to get peoples' opinions on whether this is a modification for a road car where tangible and noticible benefit can be derived.

One big question I also had was what the expected lifespan is of a timing belt. I've read that kevlar-reinforced ones can last up to 50k miles. How long does a simplex/duplex chain last?

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- Merrick
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3/71 Morris Mini K

I have run a 1310 then a 1360 with a belt drive for the last 13 years or so- it was on the S motor when I got it.
I got 40,000 miles from an original Pirelli Dayco belt, when I changed it the belt teeth were still like new.
Currently I have a MiniMania supplied kevlar one on it.
It should go 50K miles or beyond, no worries.
The only other belts available now are Chinese made- I tried one and it was pretty loose on the sprockets so I sent it back and got a Kevlar one.

Benefits of a belt vs chain-
less noise
no stretch and timing variation
no spark scatter (with electronic dizzy, anyway)
more HP, probably.

Disadvantages of timing belt on a road motor:
1. you need to remember to change it
2. take care you don't bruise the pulleys when fitting or removing them, it will mark the belt and cause premature failure
3. the front seal is less forgiving of misalignment, will leak unless you use the crank pulley to line it up before tightening the housing bolts.
4. Cost, the kits are expensive for what they are.

Chains:
The single row (simplex) ones wear too fast on performance motors.

A duplex chain and sprockets is a good all round proposition for a modified road motor.

Best duplex chains are the German `Iwis' ones, the rest available now are pre-worn when bought. This includes the AE (UK??) ones

If you buy a Rollmaster duplex kit, it includes this chain and nice light steel sprockets.
It's vernier adjustable, too.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

If you already have a double row chain, don't bother. S/H units are about $200 and new ones are $600, excluding the belt which is a further $80-$90. Expensive for near zero gain if you already have a double row chain.

On the other hand I have a belt setup and it's great

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Lillee - 1969 Morris Mini K

any more info on that?

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Rover 214 atm ....

http://www.iwis.com/index.php?id=465&L=465

You can buy Rollmaster kits that come with an IWIS chain.

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Lillee - 1969 Morris Mini K

[quote="drmini in austIf you buy a Rollmaster duplex kit, it includes this chain and nice light steel sprockets. It's vernier adjustable, too. [/quote]

I've fitted one to the Cooper S engine I'm overhauling, are they good? I'm hoping so!

Regards
Al

FYI most modern day engines (Corolla 1ZZ-FE and the 2ZZ-GE Sportivo/MR2/Celica engines, which are powerhouses of reliability) all run chains... and these are twin cam variable valve timing engines too

Chains NEVER( ) break whereas belts may if not replaced regulary...

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Lillee - 1969 Morris Mini K

Careful there production cars are built for cost and all these cars have there chains replaced at regualr intervals because of wear and stretch, some at 60,000 and the best at 100,000 intervals

For motor sport use in the old 2ltr touring cars some of the engine builders swapped to gear drive set ups or a belt drive because of better more precise cam timing,

Jon

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Roundies and Clubbies(except vans) are both ugly that is why I have Midas and a van
1293 Mini Midas Bronze,1275 Clubman van

Alfas ran 2 duplex chains, a primary one and then a longer top one- they stretched a real lot. I used to work on em.

There is no free lunch-
chains = long ones stretch and vary the timing.
belts = can break if neglected.
gears = bloody noisy.
You pays your money and makes your choice.

re the Mini belt- it is only 52 teeth long. There is no idler on the back, the initial (considerable) fitting tension is all it has.
This means no back flexing of the belt which will help its life, but as it's only 52 teeth long, it goes round more often than yer Jap motor's one does.

As I said the choice is yours, but my ignition timing stays spot on for years. I like the belt, but the 1412 I build for the wife's van will be duplex chain, the belt setup is too exxy now.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Jon, I highly doubt any chains have been replaced on 80% of corollas running out there! My mum has had 2 and I can tell you that no such work was done still running after 200,000kms

Lets not get into conversations about oil change intervals on toyotas

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Lillee - 1969 Morris Mini K

Just ask GR why BDA series ford engines have belts instead of the chain, he will explain it all for you, like doc said alfa and most OHC motors suffer with chain stretch and some worse tha others, even Toyota use belts on a lot of there twin cam engines

Jon

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Roundies and Clubbies(except vans) are both ugly that is why I have Midas and a van
1293 Mini Midas Bronze,1275 Clubman van

It gets changed about as often as the chains....

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Must be like one of those special rent a car things doc you never have to check water or oil levels

Jon

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Roundies and Clubbies(except vans) are both ugly that is why I have Midas and a van
1293 Mini Midas Bronze,1275 Clubman van

Yep, and race it like U stole it...
My brother in law killed a new Corolla years ago. Oil light came on, he thought meh- it's a Toyota, ooooh da light must be faulty. NOT...
The nice people at Toyota fitted a nice new crank and bearings.. I would have told him to sit on it.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I realise it was a little tongue in cheek....but chains most definitely can break, as I found out in my Dad's MKIV Cortina...