Sudden engine noise

[Motorsport Mickey]

37 minutes ago, Z320 said:

what I want to say (to Pete):

don't worry too much if it is tight but not exactly with the demanded torque

Depends what "tight" is Marco, you say you used a "spanner" so that's difficult to tell what torque is used, maybe not enough. I'm not sure I can get more than maybe 40-50lbs on a dog bolt (it has rounded corners) with a spanner. I'm sure nobody tightens these bolts up and thought they will come loose...they also thought they were tight enough...but weren't.

All the bolt has to do is provide enough friction to prevent the woodruff key hammering into the other side of the keyway when it is impacted by 12,000 impacts per minute ( 3000 revs x 4 fire cycles per minute), it can do that at 120 lb ft, the manufacturer thought it could, maybe not at lesser figures.

Mick Richards

Edited July 29, 2020 by Motorsport Mickey

[Z320]

I show you

Pete, sorry me, do you worry?

Edited July 29, 2020 by Z320

[Ian Vincent]

4 hours ago, Motorsport Mickey said:

All the bolt has to do is provide enough friction to prevent the woodruff key hammering into the other side of the keyway when it is impacted by 12,000 impacts per minute ( 3000 revs x 4 fire cycles per minute), it can do that at 120 lb ft, the manufacturer thought it could, maybe not at lesser figures.

Mick Richards

At the risk of being called a pedant, its a four stroke so it only fires once every two revolutions, i.e. 6,000 impacts per minute.

Rgds  Ian

[Motorsport Mickey]

Just now, Ian Vincent said:

At the risk of being called a pedant, its a four stroke so it only fires once every two revolutions, i.e. 6,000 impacts per minute.

Rgds  Ian

Thanks Ian not a pedant at all, just correcting my mistake in speaking  but you can see how multiple shocks transferred through the crankshaft can "unstick" any front pulley friction holding the pulley which is only tightened by spanner. Any loctite used will not be affected, there is no unscrewing of the bolt just loss of the sticking restriction by clamping upon the pulley which prevents it being used as as a mini slide hammer upon the keyway. 

Mick Richards

[stillp]

7 hours ago, Z320 said:

what I want to say (to Pete):

don't worry too much if it is tight but not exactly with the demanded torque

Thanks. My experience is not as great as Mick's, but I remember doing the nut up to something like 100 foot-pounds when I rebuilt my engine in the late 1980s (that's as far as my torque wrench will go) and yet when I took the pulley off recently the Woodruff key was badly worn.

The grooves in the shaft and pulley don't seem badly worn, there was very little play with a new key.

On a slightly different topic, what's the purpose of the shims behind the dog bolt? 

Pete

Edited July 29, 2020 by stillp

[Z320]

To get the starter handle in the best position to start the engine

[Z320]

More shims and the starting point moves anti clockwise 

[stillp]

Thanks, that's what I thought, Not really relevant on a 4A then.

Pete

[Z320]

Hi Mick,

there is no need to expain you: with bigger bolts  you have bigger heads, wider, longer and more solid spanners and you use them different.

This are my 28 mm and 29 mm spanners, one of both fits perfect, I don't remember which (don't want to put off the shroud around the fan).

If I use the fitting one without special care, but the way it is made for, the bolt is tight, perhaps about 80-100 Nm.

Looking on the cranshaft the engine spins left, the thread is right hand, all OK for me.

I never used a torque whench for this and never had a problem.

Ciao, Marco

Edited July 29, 2020 by Z320

[stillp]

The dog bolt is 1 1/8" A/F, I've used a 29 mm spanner as well.

Pete