The MGA With An Attitude
TENSIONER with Timing Chain Too Long - TC-318A

Here we have a bad situation. The timing chain is too long, causing the tensioner to be dramatically over-extended to the limit of its adjustment.

On 29/01/2013, Mark Hester in Perth, Australia (or London UK) wrote:
"Timing chain is a disaster. It had 132 links, so we cut two links out and fitted the master link but then it was way to short. So that idea has not floated and should not be tried. It was a 20 chain from Bob West. There is something very fishy about my engine. It has a Peter wood alloy front plate, and we suspect one gear is out of position, but its to late to measure it against the spare steel front plate. I have fitted an old, fully stretched chain of Roy's now but this is on full adjustment, even more than the new chain from Bob West".

    To which Michael (Mick) Anderson in Australia offered these suggestions:
    "There is range of things that could effect your chain.
  • First it is not a correct 3/8 inch chain but a metric equivalent.
  • It has not been pre-stretched as all good chain manufacturers claim to do.
  • The cylinder head and/or the engine block have been skimmed, lowering the camshafts.
  • The overhead camshaft bearing saddles have been line bored and the cap joints skimmed.
  • The idler sprocket and/or the chain adjuster housing are incorrectly placed on your non-standard alloy front engine plate.
  • The position of the half speed shaft should be okay, because even if line bored the centerline is not changed when there are no caps, but bearings with oversize steel backings are used".

On 30 January 2013, Mark Hester wrote:
"It just so happens that a hardened front suspension distance tube has the same inside diameter as the Twin Cam inner tensioner plunger, so we machined up a 8 mm longer piston to take up the slack".

The concern now is how close the adjuster and chain are to the steel backing plate for the vertical chain damper and also the brass oil distribution pillar. As the chain is an original used Twin Cam chain, your problem is certainly a change to the original chain path in some way.

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