NH Barrel Spiggot height

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pete.collings
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NH Barrel Spiggot height

Postby pete.collings » Mon Aug 15, 2011 8:47 am

I am trying to identify (date) a NH barrel (external pushrod tube type), and cannot find any info in the knowledgebase on how the height of the spiggot at the top of the barrel differs between early and later models.
I understand the depth of the recess in the cylinder head also matches the barrel, so a deep recess head cannot be used with a lower spiggot height.
If anyone has this info available, including when the changeover of types occurred, perhaps they could post it.

If the info is already on the knowledgebase, but I have not used the right search terms, please let me know. If not, could the info be added once verified.

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Postby Keith.owen » Fri Aug 19, 2011 1:30 pm

Pete,
I think the difference in spiggot height might be to do with the introduction of a head gasket. Prior to this the head was ground onto the barrel spiggot using grinding paste. The difference in height allows for the thickness of the gasket. I think the change came about around 1954 . I'll check up for you.

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Postby Simon.Gardiner » Sat Aug 20, 2011 11:45 pm

From 1952, bigger finning on head and barrel, head gasket and smaller spigot on top of barrel (smaller diameter and slightly lower as well).
The 350 kept an iron head until 1956, and in 1955 (I think for the one year only)there was much more pronounced finning in the area above the push rod tubes.

(I've had a goodly selection of non-matching 350 heads and barrels in my time ! )
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)

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Postby pete.collings » Sun Aug 21, 2011 9:34 am

Thanks for the replies, but what I was asking was the actual height of the differing spiggots. I have two barrels both with a spiggot height of 3/16", if someone has a barrel that they are certain is a late type, I would be most grateful if the spiggot dimensions could be measured and posted on the forum, so I can be sure whether they are an early or late type.

Many Thanks

Pete

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Postby Simon.Gardiner » Mon Aug 22, 2011 12:21 am

I've just pulled out a rather grubby 52-55 type, I wouldn't like to guarantee the spigot height(partly because it's still got the copper gasket well stuck on) but the diameter is about 3.156 - maybe 3 5/32 ?
However, I've got a feeling that the later ones also have an extra fin - this one's got 10 fins, I think the earlier ones would have 9 (I hope I'm not getting this mixed up with the 500, I don't have an earlier 350 barrel to check).
Thinking on I suspect it's the external fin size that is easiest to check as the difference is much more pronounced and should be pretty easy to pick up with a ruler - this later type has a top fin diameter of 6 1/2 , I reckon the earlier type is probably closer to 6 !
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)


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