JP Headgaskets

[flatplane8]

That's my feeling too, as clamping force is, I'm told, not much dependent on bolt pitch and the tubular studs are spaced around the cylinder in pretty much the same pattern as the rest of the studs but I might pull them a little tighter simply because they don't have the same feel as the solid studs.

 

I'd be interested in input from our South coast friends on this one.

 

Tim

 

I'd be interested too. I won't get a chance to do this until the weekend (still need to buy some wellseal and a torque wrench ). I may go 100ft-lbs all round and then 120-ft-lbs on the pushrod tubes. All the manuals I have just say 'do them up tight' or similar.

[steamraiser2]

The only torque figure that I have seen emanate from much later manuals. Just stick to the grunt to grunt and a half What ever you do do not over tighten them as the risk of stripping the studs in the block is very real!

[flatplane8]

Morning Tim,

 

You must always remember that JPs date from the two men and a whippet era when torque settings were a grunt or a grunt and a half! I have dismantled many JPs that have probably never been down since build. I'm often surprised how slack the nuts are and am convinced that,on assembly,a high torque setting is not really needed so long as the mating surfaces are flat and square to each other. That said I've come across a few that need dogging down to seal. My personal worry is the corrosion around the block studs to block threads. They often pull out and need tapping oversize to take an insert.

 

I suspect that 100 ft lb is plenty tight enough for the head studs and would agree that the 150 ft lb quoted for the tubular studs is ok. Be careful with these though, especially the cross drilled JK type, as they are liable to shear across the hole.

 

If they haven't sealed the head at these torques there is a problem. The block tops can distort ever so slightly, especially if the engine has been frosted at some time. We end up block repairing 50% of the JPs we see so it's common enough.

 

Thats good information, the heads have had a skim, I've got new genuine gaskets and will use wellseal. If that doesn't work, I think I'll look for an engine better suited to the size of barge we have, much as I like ye olde Lister.

[Pluto]

 

You must always remember that JPs date from the two men and a whippet era when torque settings were a grunt or a grunt and a half!

snip...

Certainly the case when I served my time as a fitter/turner at Pilkington Bros in St Helens. I doubt whether anyone had a torque wrench in the fitting shop. You were trained to assess each job, and use the right spanner - that is the right length spanner, so that you didn't overtighten. I don't think there are many such apprenticeships today, as we were trained to cope with anything, from overhead cranes, warehouse glass handling machinery, glass furnaces, boilers and turbine plant, through to railway locomotives. I just missed out on the old Burrows well tank engines, but some parts and gauges were still around. There was one labourer who had been a jockey who had been kept on the payroll as he was small enough to get into the well tank to hold up the bolts keeping the tank within the frames while they were tightened.

 

Later, I did have to strip down a large horizontal diesel engine for Sheffield Museum. To undo the bolts holding the flywheel halves together, I used 48 inch stillsons with a ten foot extension as the simplest way.

[RLWP]

<snip>

 

I used 48 inch stillsons with a ten foot extension as the simplest way.

 

Oh dear, what's coming next...

 

Richard

[flatplane8]

Back up and running today.

 

 

A few more pictures here

 

I did all the studs up to 100ft-lbs, then did the pushrod ones in stages up to 130 ft-lbs. It seems to leak water from the corner of one of the heads, but not much. I'm not taking it apart again

Edited June 27, 2011 by flatplane8