36 replies to this topic

[Retroman]

Didn't see the photos, it was the fact you measured it with a vernier, not the gasket.

[Steve220]

Measured 'what' with a vernier?

 

I did measure the gasket with my digital verniers. I've fitted the whole thing up now and measured again, it is bang on! Well, i've learned my lesson.

Edited by Steve220, 11 March 2018 - 05:31 PM.

[carbon]

 

Ok Steve thanks for the clarification I have added my comments in italics

- On first view the crank sprocket appears to sit more proud than the camshaft. The photo was taken prior to tightening it all down although had been pushed back with a socket as a drift.

   Having thought about the photo I think it could just be the chain deceiving all of us, and now its been turned over a few times now it has settled to a more central place. The sprockets can't be seen well on the photo.

 

- The crank end float was within tolerance at the time of installing, it was actually on the tighter end of the tolerances.

How was it measured?, and how much float was there ?

 

- After running the crank over around 10 times i re-did a line of sight check then measured the distance between the chains outer face and the back plate. As above.

The distance at the crank sprocket to the back plate was 24.00mm and at the cam sprocket it was 23.80mm. Measured with digital verniers.

  Ok so you have measured the crank sprocket and cam sprocket, that will give you an idea of how well the chain sprockets are lined up, and has nothing to do with crank end float. So the measurement you gave of 0.2mm is the pulley misalignment, not crank end float.

 

To make sure the pulleys are parallel it should be a straight edge across both. Its usual to shim the crank pulley, but yours would seem to be the other way. It could well be that everything is OK, not sure if your method of measuring is accurate enough.

 

Crank end float was measured using a DTI and measured 0.055mm (0.0022").

 

Two thou of crank end float is tight, if it is a 1275 and you are planning to use high rpm would suggest at least twice as much crank end float.

[Steve220]

Ok Steve thanks for the clarification I have added my comments in italics
- On first view the crank sprocket appears to sit more proud than the camshaft. The photo was taken prior to tightening it all down although had been pushed back with a socket as a drift.
   Having thought about the photo I think it could just be the chain deceiving all of us, and now its been turned over a few times now it has settled to a more central place. The sprockets can't be seen well on the photo.
 
- The crank end float was within tolerance at the time of installing, it was actually on the tighter end of the tolerances.
How was it measured?, and how much float was there ?
 
- After running the crank over around 10 times i re-did a line of sight check then measured the distance between the chains outer face and the back plate. As above.
The distance at the crank sprocket to the back plate was 24.00mm and at the cam sprocket it was 23.80mm. Measured with digital verniers.
  Ok so you have measured the crank sprocket and cam sprocket, that will give you an idea of how well the chain sprockets are lined up, and has nothing to do with crank end float. So the measurement you gave of 0.2mm is the pulley misalignment, not crank end float.
 
To make sure the pulleys are parallel it should be a straight edge across both. Its usual to shim the crank pulley, but yours would seem to be the other way. It could well be that everything is OK, not sure if your method of measuring is accurate enough.

 
Crank end float was measured using a DTI and measured 0.055mm (0.0022").

Two thou of crank end float is tight, if it is a 1275 and you are planning to use high rpm would suggest at least twice as much crank end float.

Don't intend to use high rpm. Rob Walker told me it would be fine for my application.

Edited by Steve220, 11 March 2018 - 07:51 PM.

[Earwax]

I have seen a timing gear set with the same problem. - It was a standard build, standard double chain timing gear etc. Went and bought a Rollmaster set- problem disappeared. 

[Retroman]

Measured 'what' with a vernier?

 

I did measure the gasket with my digital verniers. I've fitted the whole thing up now and measured again, it is bang on! Well, i've learned my lesson.

Glad its sorted, never come across a front plate gasket so thick, and as such it never causes your initial issue.

 

The usual way with straight edge and shims on the crank pulley is way to go.

 

It was the measuring of the spockets and or chain with the vernier that threw me.

[alex-95]

Does anyone know where to buy the thicker gaskets? I bought one from minispares but is the 0.4mm ones where I need the 0.7mm thick? I'll have to make one if not.