Atlas spigot removal...

Hi Ernie,

In my experience i would not recommend the filler rings. Just use the gasket meant for the non spigoted barrel, I have seen the aftermath of, i assume, the filler rings getting caught by the piston and being pulled or making their way into the combustion chamber. Running without them will not cause a problem, the annular recess formed by the lack of spigot will eventually fill with carbon and thats the worst that can happen.

This is only my humble opinion.

Regards

Marty

I just did some sums - and if I'm correct, the volume of the spigot is round about 3% of the combustion chamber volume. It's hard to believe that would make any difference.

I haven't a clue about possible effects of thechange in shape on pre-ignition or anything like that.

There has been recent discussion on the spigot filler rings, Ernie - have you looked at the search?

I had the spigots machined off my 650 barrels, and purchased filler rings from Norvil. When they arrived, they proved to be a sloppy fit in the recess, and stood proud of the head. When I spoke to Les Emery about it, he said they need to be stuck somehow into the head, and then machined off flush. I spoke to the local engineering shop who carry out all manner of engineering work on engines, from reboring to full rebuilds of anything from outboards to huge marine engines, and they said the likelyhood was that the spigots would break of if an attempt was made to machine them. I returned them for a refund, and fitted the head with a standard spigotted head gasket. My thought was that if you fit the gasket from the non-spigotted barrel, a whole outer ring of it would be exposed above the barrel, so I could see no benefit to it.

All seems ok in that regard.

Ian

See below.

You make a good point ian, that fitting the unspigoted head gasket exposes a bit of the gasket into that annular recess. I used a head composite head gasket and measured that the fire ring would still be compressed by the head and indeed it worked perfectly.

I can't see an issue with using the head gasket for the spigoted barrel apart from it wouldn't have a fire ring or edge that was designed to be exposed to combustion chamber conditions, the spigot already serving this purpose. I've not examined all of the gaskets available for this application so it's highly possible i could be wrong about this.

The main problem with the filler rings is they need to be exact in every dimension. Too thick and they hold the head off the gasket, too thin and they will be loose in their recess. Too wide and they are in danger of being caught by the piston. Machining them is not impossible but they are just unnecessary in my humble opinion and have potential to be problematic.

I realise the OP was only wanting information on where to obtain the aforementioned rings, but it's an interesting subject. Or is it??

Peace out.

Marty

I didn't bother with filler rings. Everything worked just fine without.

Thanks for this guys - it saves me asking the question! When I had my barrel rebored to +.040" one of the spigots split circumferencially so I was wondering what the best recourse was. It seems to be to get the spigots machined off and fit either a standard gasket for a spigoted barrel or possibly one for non-spigoted. Or maybe just get that damaged one machined off giving the head a touch more stability in its alignment with the barrel? In which case I would obviously fit a standard spigoted head gasket.

I recall seeing a horror pic of a chewed-up spigot ring a while ago!