Series 2.25L timing chain parts , tensioners

[TJR]

While looking to get some parts form my 2.25L rebuild.. I was looking at the Rover parts catalog.. PG 10

http://www.roversnorth.com/store/p-3615-chain-tensioner-225-l-.aspx

They show a piston type timing chain tensioner RNB654 &RNC741, which is the kind I have ,

and also a Pad style tensioner that appears to use a different timing chain.

What is the prefered one and why?

Why are there two styles? simply cost??

Thanks for any insight. .. Talbot

[Eric W S]

The piston is the earlier design and the pad is the later design.

I prefer the piston myself.

Reason for the change was most likely cost cutting at Leylend. You'll notice things like that throughout the RN Catalog. Some III parts are better, some not.

[TJR]

So the improved design just rubs against the chain? i.e. no rolling element?

It appears there are 2 different chains..is the pad style one shorter and runs like a typical american V8 timing chaning i.e no tensioner?

I'm curious to see of pick of this style.. TJR

[Eric W S]

The old design is pictured in the RN catalog...

[bobzinak]

the 2.5 engines had the piston at least in my 2a.. the 2.5 had the rub block with shorter chain..the advantage to the piston setup is that you can have the cam gear attatched to the cam, so you can put on or remove timing chain from cam gear.. it is a bitch to try to put the gear on with the chain already attatched.. just be aware that the chains stretch. and you could have altered timing as it can not jump to the next locking dog on the tensioner. Mine once got so loose it started to rub on the inside of the front cover..a very odd noise...I prefer the piston one because it is a little more user friendly..more maint in the end..but rovers are a hobby as much as a mode of tranport..bz..

[StX_Rovers]

When we rebuilt the 2.25 D in our 67 109 wagon Les at RN (I believe it was Les) recommended sticking with the original style.

I seem to recall that when assembling it you don't want to preload (pushing out the piston) it too much, let the oil pressure do it.

If the Cam gear is in good shape and has the 7 keyways at slightly different orientations cut in it consider reusing it. The replacement ones only have one slot and when I checked the cam timing on Michelle's 88 the cam is 3-4 degrees retarded with the new style gear. Now I have to find an offset cam key to get the cam timing correct. I am hoping A-series BL engines and Landies have the same key for the cam as Mini Mania (I am sure others also) carry offset keys for cams. Remember you want a cam key that is offset for HALF the change you require as you measure cam timing at the crank. I don't care if it is a Landy or a race car, you should always degree in the cam. 2.25 Rovers need all the help they can get on the power front, with the cam in correctly you should get better power and mileage.