MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Pic of Timing chain - in line?

Took this during engine rebuild - does it look lined up ok?

Samuel Sullivan

Extremely difficult to judge, given camera angle/distortion, but no.
The slack is on the wrong side for checking, which makes it worse.
The four points - crank & cam centers and the two marks must lie in a straight line when at TDC.
In this pic it looks to me like the crank is slightly past TDC, but the cam mark has not gotten to the centerline yet, and making the drive side tight will add to the error.
Also, it may be a trick of the focus and lighting, but the sprockets appear to be worn a good bit.
And, it looks like the sprockets are out of line front to back, resulting in wear on the front face of the cam sprocket. This is set by shims behind the crank sprocket, as detailed in the book. Not uncommon that people leave the shims out, which will cause rapid chain wear or failure.

FRM
Fletcher R Millmore

I think that nay be assembly lube causing the distorted image but I would have to agree with Fletcher about the alignment. You need to get a shot from directly in front, try and take it so your looking straight down the crank bolt hole for a more precise image. The marks have to be on the center line of the crank and camshaft when lined up.
Denis
Denis4

Samuel. The workshop manual obviously has the alignment procedure, but I assume you don't have one. Best way to describe it is

Camshaft key way at about 1 o'clock position
Crankshaft key way at 12 o'clock (TDC)
both marks on the wheels aligned so that a straight line can be drawn through the centre of the crank, through the two marks and the centre of the cam.

To achieve alignment the camshaft is rotated until the marks all line up.

Hope this helps. My manual is stored as a PDF document and I don't know how to copy and paste from it.

Tony
Tony Oliver

Hi Samuel,

Apart from the above comments, note that the alignment of the dots is correct for #4 cylinder, so don't try and install your dizzy at this setting, rotate your crank a full 360 to bring #1 to its timing point.

Herb
Herb Adler

Looks half a tooth out to me and when the chain is pulled tight with the tensioner it will be a whole tooth out Willy
WilliamRevit

Same here, both dimples are noticeably to one side of the centre-line between the two shafts. Put the crank dimple on the line and the cam dimple will be pretty close to one tooth out.
Paul Hunt 2010

This thread was discussed between 02/07/2010 and 03/07/2010

MG MGB Technical index

This thread is from the archives. Join the live MG MGB Technical BBS now