Jump to content
Sign in to follow this  
Bulatovic

Cam timing question - chain stretch

Recommended Posts

Hi everyone,

in finalization of my mechanics major overhaul of the '66 4A i own, it's come to the point of degreeing the camshaft.

It's a TT1004 cam, with the following specs: 

Inlet Timing: 37-63

Exhaust Timing: 73-27

Install Figure: 103˚

Cam Duration: 280˚

Reading everything that contains words "camshaft", "cam", TT1xxx, or similar, i've found that this specific one works best when setup just as per specs - installed at 103˚.

However - coming from some experience with Minis, there is always talk about timing chain stretch and that you should expect it to give in as much as 2˚ in first 2000 miles (not just folklore, but with some actual measuring behind the figures  - 1.0˚ in first 150 miles, 1.5˚ in 1000 miles and as much as 2˚ in first 2000 miles).

Has anyone experienced anything similar with our 4 pots here, and does anyone take this into consideration when degreeing the cam?

I got the chain and the gears from TR Shop, not really sure on the manufacturer and its stretchability...

Cheers!

Luka

Edited by Bulatovic

Share this post


Link to post
Share on other sites

"Has anyone experienced anything similar with our 4 pots here, and does anyone take this into consideration when degreeing the cam? "

No, but given if it's a road going car any erosion of performance is not noticeable, and I would never set up a cam initially incorrectly in the hope that in a couple of thousand miles it's compromised cam timing is changed by a chain stretch back to it's correct setting. Set it to the degrees it's supposed to be and check it in a couple of thousand miles if you worry about it, the camshaft timing is easily readjusted in car with the timing cover removed to whatever you desire.

Mick Richards

Share this post


Link to post
Share on other sites

As you probably are aware, the suggestion is that the cam should be installed slightly advanced if you cannot get it spot on, not retarded.  This I guess will take account of chain stretch (causing retarding of the cam)

Perceived wisdom is buy the best quality chain you can get.

Cheers

Peter W

Share this post


Link to post
Share on other sites
1 hour ago, Motorsport Mickey said:

and I would never set up a cam initially incorrectly in the hope that in a couple of thousand miles it's compromised cam timing is changed by a chain stretch back to it's correct setting.

+1

Share this post


Link to post
Share on other sites

Thanks very much guys for your input!

What Mickey said makes perfect sense - not sure why i never thought to re-adjust at the end of the season or something like that... :)

103 degrees it is!

Cheers

L

Share this post


Link to post
Share on other sites

Wear can account for several degrees at the crank. I have mine installed 3 degrees advanced to offset this, expecting that it will eventually be 3 degrees retarded by the time it is done. I have found that the clearance in the cam sprocket holes allows for at least 6 degrees of adjustment. No, the sprocket doesn't move on the cam if properly tightened, and if it's not the bolts will shear off anyway.

It never occurred to me that TRIUMPH may have factored wear into the original settings.

 

Cheers,

Tom

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.