Cambelt identification question

I am having trouble identifing from the engine number (18K4FN04 363687) which cam belt I need to order from Elise parts, either the log one and auto tensioner or the short one and manual tensioner?
Also is the Piper belt one worth the extra money?

Yo Si, I understand the Piper is made of better stuff and hence less likely to perish, more of an issue for low mile cars than them actaully wearing out I’d have thought. I fitted one recently.


Hi Ian
But do you know if you have a long one or a short one

I’d guess the longer one as I assume the difference is for the A/c, which I assume means an increase in length. Too many assumtions to be safe, I’d check with the Edwards, DVA, another reply, etc.


Just rang the Edwards I need the short one thanks

Because of no A/C?


Sorry Ian nothing to do with A/C just to do with the type of tensioner


The belt you need is the short one, but make sure you also have the wider belt, if you are buying from a dealer, ensure you get the VVC belt, this is the correct one for an Exige or indeed any 1800 engine with a manual tensioner.

Aircon is never driven from the cambelt, only ever from the ancilliary (alternator) belt. The ‘longer’ belt is only two teeth longer to accomodate the different geometry of the auto tensioner. All ‘long’ belts are also wide, not all ‘short’ belts are.


but make sure you also have the wider belt

is there any quick way of checking this?


Is there a part number difference between the various belts ?

The wider belt is 25mm wide, the narrower is 23mm wide, quite often narrower belts were used to build VHPDs which seems counter intuitive.

I dont know the OEM part numbers, but for reference the Piper part numbers are

TBP17 wide shorter belt (manual tensioner)
TBP33 wide longer belt (auto-tensioner)


The wider belt is 25mm wide, the narrower is 23mm wide

2mm does not sound like a big difference - why is it that important?

cheers Dave

2mm does not sound like a big difference - why is it that important?

If Rover decided to use a wider belt when they already had the narrow one, they should have had their reasons…


The narrow belt was designed for the stock engine which doesnt go beyond 7000, and has a low ineretia valve train. The VHPD goes to 8000, has stronger valve springs, more agressive cams and heavier valves that all increase the loadings n the belt. Why use the narrow belt on the most stressed engine when there is a stronger one available?

The wider belt was developed for the VVC because the narrow one wasnt up to the job, the extra shock loads on the VVC setup required a beefier belt. The wider bottom sprocket was then adoped through the whole range of engines together with the automatic tensioner with wider belt at the same time; so now even the base 1400/1600/1800 engine has a 25mm belt as standard, why fit a 23mm one to a VHPD?



thanks for the comprehensive answer.

Have I got it right then that the best spec is:

  • 25mm belt
  • auto tensioner
  • wider bottom sprocket

and the auto tensioner and wider bottom sprocket are just straight swaps.

Just had mine changed, but didn’t appreciate the above at the time. I do know that I got a new tensioner at the same time though, as I was told it was a part that “could” go and it was easy to change at the same time as the belt.

Tha auto tensioner is the spawn of Beelzebub, on no account use it, nor is it a direct swap, the head will need drilling and tapping.

The older munual tensioner is the one to use and is standard fitment on the VVC and VHPD, hence the recommendation of the VVC belt. The wider bottom sprocket is standard on all 1800s made and all 1600s/1400s from 1998.



once again thanks