11 replies to this topic

[A1111j]

Hi has anyone fitted this kit and what are your views onit?

[Spider]

I haven't fitted their kit, but did try a few belt drive kits some years back. They fit OK and hold timing well, but the belts do need changing every 12 000 miles (20 000 km), unless it's a Kevlar Belt which can go for about 20 000 miles. The short life is due to their short length. The other issue is if you get an oil leak up that end of the engine, it's all over for the belt, which could be a disaster if your valves can contact the pistons when open.

 

I came away from this after weighing up the pros and cons and went back to a chain. For a road car, I don't feel there's any worthwhile gain though some risks.

[Cooperman]

Chris, I think all standard A-series engines are 'non-interference' in that even with the valves fully open the flat of the valve face does not reach the level of the piston crown. 

Maybe an ultra-high lift cam could cause interference if high-lift rockers were fitted.

Personally I don't like cam belts. A proper chain is so much safer and more reliable. I've seen the results of belt failure too many times.

[mini-geek]

I bought one and I'll be removing it very soon..

Oil flowed out of the thing

And it's simply not necessary unless you're running a full race engine and need to get every last HP out of it..

[Spider]

Chris, I think all standard A-series engines are 'non-interference' in that even with the valves fully open the flat of the valve face does not reach the level of the piston crown. 

Maybe an ultra-high lift cam could cause interference if high-lift rockers were fitted.

 

Hey Pete !

Yes, your right here that most are but I've built and worked on a few there were. Not knowing the OP's engine spec. I felt it best to mention it, at least it can be considered.

[A1111j]

Great thank you. Any recommendations on chain and brand and also what brand rocker rockers I should get my look a bit worn.

[Midas Mk1]

I’ve had a belt drive (not med) fail on the vernier part and give me 10 degrees of cam scatter, never again and always back to a duplex (swifty or med for me).

[bluedragon]

The original Triger cam belt drives were claimed to give 20,000 miles of life on the conventional belt and 50,000 for a Kevlar unit. The MED unit (with no tensioner) looks very similar to the old Trigers. I wonder if it can use the same belt.

 

If I were setting up a new cam drive today, it would be using a simplex IWIS chain instead of a duplex. Less friction, no mods needed and the high-quality IWIS chain doesn't "stretch", which is the main reason for a duplex setup IMHO.

 

 

Dave

Edited by bluedragon, 31 August 2021 - 06:50 PM.

[Spider]

The Duplex Chain Kits I've been using on most builds in recent years has been one from Mini Spares. They have a few, this particular one has steel sprockets and a Duplex ISWS Chain. I still go for the Duplex kits as with the ISWS Simplex Chain (and there's also a Japanese Chain I uses that's at least as good) last well, the Sprockets still wear at just short of twice the rate of a Duplex. Having said that, you should get respectable life from a Simplex. For what ever it's worth, I've only fitted Simplex to Track cars.

[mini13]

I haven't fitted their kit, but did try a few belt drive kits some years back. They fit OK and hold timing well, but the belts do need changing every 12 000 miles (20 000 km), unless it's a Kevlar Belt which can go for about 20 000 miles. The short life is due to their short length. The other issue is if you get an oil leak up that end of the engine, it's all over for the belt, which could be a disaster if your valves can contact the pistons when open.

 

I came away from this after weighing up the pros and cons and went back to a chain. For a road car, I don't feel there's any worthwhile gain though some risks.

on this subject.... with a certain amount of authority..... dont ask how i know.....  something about the Tee shirt etc etc

 

its a safe assumption that you'll be running a hottish cam, in which case the valves will contact the pistons.... and also the cam lobes will take a swipe out of each of the rods/rod bolts.

[Ethel]

Sure I heard somewhere that the crank can hit the cam lobes if the timing gear goes AWOL on a 1275 - not that I've ever investigated that theory myself. The belts are short, but they follow a much less tortuous path than many OE belts. I just changed one after 130k miles of snaking its way round crank, cam, injector & water pump pulleys, with a couple of tensioner/idler pulleys thrown in. I suspect the likes of KAD erred heavily on the side of caution, but there's little incentive to find out as swapping one is so easy in comparison to other belts - or A Series timing gear.

[mini13]

Also, all the belt knits I have seen use the smaller trapezoidal belt profile ( basically copying the trigger setup).

 

after my issues I looked into making my own kit, and found that the belt or the rear of the MGF VVC engine looks to be a good substute and as the larger more usual belt profile used for oem cambelts.