broken barrel spigots

How much is missing Skip? If it's not much I'd take the lazy way out and tidy up the edges and put it all together. Otherwise there are loose fitting rings to fill the gap. Recipe for trouble I should think.

No doubt there are more expert views later.

Happy New Year!

I have a pair of 99 barrels with a few broken bits off the top, like you, Skip I am hoping someone has the answer as to the best course of action before I get around to putting the engine together.

In my case the bore is good and I bought a pair of unused Italian +40 pistons with rings as a part of the deal.

Hope someone has a solution?

A common problem, especially once a barrel is rebored and the spigots get rather thin. In my case it was machining off the remains of the spigots. I didn't fit rings to fill the resulting annular cavity (I know, I know, proper engineers lie down and rest now). However, the cavity soon carbons up to it doesn't really matter.

My pathetic justification was the need to get the bike back on the road pronto.

The spigots definitely help prevent gas leaks as the hot exhaust gases are not attacking the inner edge of the gasket which can gradually erode and undermine it. The spigot is there ideally to create a half decent seal with the head and some heads on single cylinder engines are ground together to mate them together to form the seal without a gasket..

With a spigot, what remains of the hot gases passing over it (and now thermally quenched) is directed onto the top edge of the gasket rather than the side. However car engines don't usually have any spigots at all and they work OK.......so you might well try how it gets on as it is without doing anything....depends on the gaskets quality then.

1) As you suggest. The spigot could be fully machined flat and a concentric slot milled round each barrel top. A steel ring * made from strip and welded together could then be tapped in to restore the original set up...noting that the new spigot will be narrower but still effective I believe.

* A better steel ring could very easily be made on a large lathe....just a few minutes work.

2) Another way would be to mill away the top barrel surface to leave a new ridge and fit a compression plate of the same thickness as the metal removed under the bottom of the barrel (base) gasket face....More drastic possibly?...but a chance to increase the compression ratio should you wish...

3) PS Just thought of another possible way....I wonder if one of those steel barrel liners could be fitted and the top left proud from the previously machined flat barrel top?. This protrusion would re-create the spigot....no harm in not pushing it down flush to the top....This seems the perfect solution as you get a new barrel and you can then re-use your older original size pistons....if possible.... I consider this the best idea ...

Les

A couple of years ago someone posted here a picture of a mysterious steel worm jammed in the combustion chamber. It turned out to be the remains of a filler ring like Les describes. I think there might have been a link to one of out usual parts supplier's web site.I wonder what difference it would make to compression ratio if they were left out? Not much is my guess.

Hello Skip and everyone reading this thread. Happy New Year to you all. When I have used barrels with broken spigots I have found it best to ground of the remnants and then use a composite gasket. The late 650s and 750s did use a spigot-less set up with a composite graphite impregnated head gasket. For racing I usually fitted a ring into each of the recesses in the head and then use a solid copper gasket but on the road a composite gasket without worrying about the recesses was sufficient. RGM sell the gaskets. Cheers, Howard.

Previously David Cooper wrote:

A couple of years ago someone posted here a picture of a mysterious steel worm jammed in the combustion chamber. It turned out to be the remains of a filler ring like Les describes. I think there might have been a link to one of out usual parts supplier's web site. I wonder what difference it would make to compression ratio if they were left out? Not much is my guess.

Hi David...Please tell me where on my earlier reply I describe (or even mention) a "Filler Ring" ? ....Thank you....Les

I have made up a quick diagram to show what I meant...there is no way the new ring can fall out when the head is bolted down...see attachment please:

Attachments
Barrel%20Spigot%20replacement.JPG

Sorry Les - I didn't mean to upset you - but it's worth owners knowing that filler rings are used and that one poster has shown how they can go wrong (maybe because the one that was found broken up inside the chamber was home-made from a bent bar and was not a full circle? Who can tell?).

I think your solution number 3 looks like the best way to go. I know my spigots are very thin because PO re-lined it - so half the spigot is actually the sleeve.

I see RGM advertise liners "with spigot".

http://www.rgmnorton.co.uk/dept/cylinder-liners_d0142.htm

They also advertise:

http://www.rgmnorton.co.uk/buy/alloy-recess-ring-for-converting-spigoted-cylinder-head-to-non-spigoted_171.htm

Sorry to you too David....I realise now you might have thought I was "shouting" by my use of BOLD font but I just used the BOLD type as to highlight and differentiate my reply from your quote that I included....

I personally would just remove the entire spigot and bolt it up with a gasket that Howard recommends and keep my fingers crossed....but maybe the addition of the RGM rings that you point out will also help...

The RGM spigot filler rings could, as you initially told us, fall out if they were not thicker than the head gasket. They need to be slightly thicker to get pinched before the gasket thickness limits the final tightening compression of the head and remain trapped in position. Certainly if this was the case the rings would create an excellent seal....so one should measure the comparative thicknesses before using to check this..

Best regards.

Les

The 'filler rings' P/N 025494, mentioned by David C are actually specifically for the early Atlas Heads, C/N 23166, so that they could be used with spigotless barrels. You did have to remember to drill the bolt holes, each side of the plug, out from 5/16" to 3/8".

I believe that you can still purchase specially made solid copper gaskets that have a little extra meat to allow for use on the post 1966 650 spigotless barrels and heads. These would be fine for a 99 engine and probably also work on an 88 barrel. I can not recall exactly who is manufacturing such gaskets but possibaly a call to RGM may help.

Also, somewhere within the NOC Help Archives is a posting from a chap who got his local engineering company to slice some Aluminium tubing into rings that fitted inside his early 650 cylinder head. There must have been some interesting maths involved, in this scheme, to get a good fit and there was no follow-up to the success or failure of his plan. No reason why they should not have worked, however, as the gasket would have kept them in position.

Adding to the above about custom made 650 cylinder head gaskets, this company in the USA....Copper Gaskets can be found on Ebay claiming as below........

YOU ARE BIDDING ON 1 COPPER HEAD GASKET FOR A NORTON 650 TWIN ENGINE BORE 2.845 X .042 THICK. I CAN CHANGE BORE AND THICKNESS FOR YOUR APPLICATION PLEASE EMAIL FOR MORE INFORMATION ON THIS. COPPER GASKETS UNLIMITED IS A CUSTOM GASKET MANUFACTURE FOR HIGH PERFORMANCE ENGINES AS WELL AS STOCK APPLICATIONS. ALL COPPER GASKETS ARE CNC MILLED FROM COPPER SHEET.

I believe Norvil have the spigot rings for the smaller engines.

I had about half an inch of spigot missing off one of my Dommie's cylinders for many years and it never gave me any problems.

When I got my '65 Atlas, it was fitted with spigotless cylinders and a spigot head. The head flange's narrower land between the combustion chambers compared to a spigotless head had meant that the matching (composite) head gasket was similarly narrow and had blown at that point. The head and cylinder faces were true, but it is obviously not known what torque or tightening sequence the PO had used. Judging by the rest of the bike, it was probably wrong!

My solution was to get a spigotless head, as I wanted the confidence of a full width mating surface, but I could have taken the spigot head to Norman White, who can fit conversion rings properly.

Previously les_howard wrote:

The spigots definitely help prevent gas leaks as the hot exhaust gases are not attacking the inner edge of the gasket which can gradually erode and undermine it. The spigot is there ideally to create a half decent seal with the head and some heads on single cylinder engines are ground together to mate them together to form the seal without a gasket..

With a spigot, what remains of the hot gases passing over it (and now thermally quenched) is directed onto the top edge of the gasket rather than the side. However car engines don't usually have any spigots at all and they work OK.......so you might well try how it gets on as it is without doing anything....depends on the gaskets quality then.

1) As you suggest. The spigot could be fully machined flat and a concentric slot milled round each barrel top. A steel ring * made from strip and welded together could then be tapped in to restore the original set up...noting that the new spigot will be narrower but still effective I believe.

* A better steel ring could very easily be made on a large lathe....just a few minutes work.

2) Another way would be to mill away the top barrel surface to leave a new ridge and fit a compression plate of the same thickness as the metal removed under the bottom of the barrel (base) gasket face....More drastic possibly?...but a chance to increase the compression ratio should you wish...

3) PS Just thought of another possible way....I wonder if one of those steel barrel liners could be fitted and the top left proud from the previously machined flat barrel top?. This protrusion would re-create the spigot....no harm in not pushing it down flush to the top....This seems the perfect solution as you get a new barrel and you can then re-use your older original size pistons....if possible.... I consider this the best idea ...

Les

When I first got my 650SS it had cracks on both spigots. A ring of metal trying to detach itself. I had liners put in which re-established the spigot. That was in the 70s so I have no idea who did the job but can confirm that it is a possibility.

I don't recall anyone mentioning it before, but once the spigots have been machined off the barrel, why not build up the spigot recesses in the head with weld, and re-machine? Surely that would be a better job than using ill-fitting rings, or just leaving it and putting up with a narrow gasket face?

Actually, re-reading the thread, I see that Skip DID mention welding, although in that case the rarity of the beast precluded it. Not that it needs to, because if the barrel was ever re-lined in the future, it could be done with spigotted liners, and the recess in the head re-machined.

Best option imo. Too late for mine, as I believe it now needs re-lining; with spigotted liners, of course!

In the days of Hillman Imps 875/998cc 4 cylinder it was a standard countermeasure to fit "Wills" rings to the alloy - alloy( head to block) joint to thwart the so common failure at this point. Still marketed byTrelloborg.

If they are good enough for Kusmicki then they are good enough....

Previously eugene_brolund wrote:

Hi All,

I will be working on one of my 600cc Dominator engines shortly & in reviewing some of the parts & see that one of the "spigots" on the top of the cylinders has a chunk missing.

My thoughts were to mill off the spigots of both cylinders as was done on later engines (this is a 1960 engine). I assume I would then need to machine a pair of rings to press fit into the cylinder head to fill the gap where the spigots would have gone correct?

Has anyone had this issue, and how have you dealt with it?

Happy New Year,

Skip Brolund

Hi Skip, just found your letter so I may be a bit too late, however I am busy rebuilding my 1957 99 and had the same problem. mine was slightly worse in that the engine blew in 1970 and the head wasn't removed until January this year. even though I took all care half of one of the spigots came adrift with the head and also broke into the top of the bore by about 0.03". I considered relining, milling off the spigots and machining counterbores to fit rings to reproduce the spigots etc. Having read that later models became spigotless and RGM sold filler rings I opted for going spigotless. I milled the head to remove the spigots + the extra 0.03" to tidy up the top of the bores. On checking the RGM ring sizes they were too big so I ordered 250mm of 3"x1/4" wall alloy tube from 'materials 4 me' at £10.25 and made my own. I made sure the recesses in the head were clean and measured them then turned the rings to +0.003" in dia. and length, with a small chamfer to clear any corner radius. then as suggested by one of the other replies I heated the head and cooled the rings in the freezer and they dropped in perfectly. I also tapered the ring bore to blend with the cylinder bore and the sphere of the combustion chamber. the 0.003" extra length ensures extra nip onto the gasket edge. I have purchased a spigotless gasket to complete the job.

Removing the extra 0.03" from the barrels meant that the pistons would protrude into the head so I machined 0.03" tapered to zero off each piston sufficient to clear the head.

The piston/valve clearance needs to be checked as the pistons are 9:1 ratio, any problem I can always fit a compression plate under the barrels.

If you haven't got this far yet I still have about 200mm of alloy tube and could slice a bit off and post it to you, it is much easier than machining from solid.

Regards, Dick Hudson

Attachments
026-jpg