Timing Chains

[David Morris]

Hi there,

I was wondering if anyone has any advice on our timing chains? How often should they be changed? Being duplex, do we expect them to last forever? Is there any advice on tensioners?

In many ways they are the unsung heroes in our engines. We might get worried about oil leaks, head gaskets etc. but timing chains - no problems.

However, we must admit, they do rattle and just how long can we expect them to last before needing to replace them?

I have a spare timing cover where someone has fitted a Reynolds spring-assisted slipper tensioner, which I am pretty sure was not original. The design of the timing cover, which is very accessable, must lend itself to the fitting of some form of slipper tensioner, and perhaps you could have an adjusting peg coming through the side of the cover?

Maybe the timing sprockets wear faster than the chains? I have seen some with really sharp and worn teeth. In this case, does the club have spares?

Any ideas or advice?

All the best,

David

[Leo Bolter]

Hello, David

Many years ago I went down this path by the fitting of an externally adjustable chain tensioner. I wanted to eliminate the chain noise that was still evident even after the fitting of a good quality new chain.

Unfortunately I'm not at home at the moment, and so can't access my images and drawings, but I'll post my information within the next few days of my return home . . . .

I will return . . . .

Leo

[Leo Bolter]

Well David, I’m home again.




I’ve posted details of the notes I made in 1998 of the fitting of the chain tensioner. It's in my album in the Gallery TOPIC

These pictures and scans will give you an idea of what was done, but if you should find the scans of the sketches are a little indistinct, please contact me and I’ll send you a zip file of larger images.

Lord knows if Ford Mk I Cortina parts can still be purchased, but if nothing else, what I have shown may serve as a basis for the adapting of a slipper from another more modern car . . . .

Cheers, Leo

[Mike Allfrey]

Dear David,

The most important point about a Javelin/Jupiter/10 hp Four timing chain is that it is a genuine endless Renold chain. With respect to a Renold chain, the link pins are radially peened over (full circle), whereas cheap imitations are generally only peened on two faces per pin, 180 degrees apart.

Cheaper chains are available, and surely these are very tempting to the average Jowett owner - my advice is to stay clear.

In addition, Renold have a very good warranty system.

Points to watch for are sprocket condition and camshaft bore wear,

Never use a chain with a joiner link. Very tempting, I know, but can be clattery.

In 1967 I tried to make a timing chain tensioner with adjustment rather like that on a Bradford CC model. It worked, but was very noisy. Enquirers were informed that it was the supercharger drive noise!

I soon discarded it and dumped it. The original system is adequate.

Why does Jowett come up as being underlined. Not known to the spelling check system no doubt - but on Jowett Talk?

We had 80 mm of rain the other day - Yippee!

Regards,

Mike Allfrey.[list][/list]

[Chris Cole]

Thanks Leo & Mike for info about tensioners. Any idea though on replacement intervals for the chain & pulleys as originally fitted. I think you ought to change both at the same time as a worn, or 'hooked,' pulleys don't last and will wear out a new chain. The question is how clattery does it get before you change these items? Also what can one do, if anything, about cam shaft wear?

[Leo Bolter]

Chris,

You said:

Also what can one do, if anything, about cam shaft wear?

I suggest you go to the top of the Forum page to "Search", click on the icon and then in the topmost box type these words: "camshaft and wear" (without the quote marks of course). Then press the "Search" button . . . . all posts where the words have been included will be listed and those words will be highlighted . . . .

Have a good read . . there's plenty of it!

Regards, Leo

[Mike Allfrey]

G'dday From The Steamy South!

In an ideal world a new chain should be fitted on to new sprockets. A worn set of sprockets will accelerate wear at the new chain.

Replacement intervals?

With a Jowett being a 'hobby' car now, probably never! A Renold chain is of the best quality and is very reasonably priced. Provided the oil supply is kept up to the drive system via the oil jet in the oil feed pipe elbow. This is very important.

Bill Lock has oversize bearing journal camshafts and suitable cam followers to match in stock. A properly set up and tunnel bored crankcase set should last many years, enjoying the benefits of modern lubricating oils.

It is important to change the oil and filter element at least once a year, regardless of how few miles the car may have travelled in the twelve month period.

We have to take into account that these cars, in several cases, have been running satisfactorily now for more than fifty years - that speaks volumes for the quality and durability of the drive.

However, we can all be fiddlers at times!

Regards,

Mike Allfrey.