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by volker.halbach
Sat May 01, 2021 9:11 am
Forum: Four stroke
Topic: 4469 piston rebore clearance
Replies: 8
Views: 633

Re: 4469 piston rebore clearance

Thanks, Paul.
by volker.halbach
Fri Apr 30, 2021 10:25 am
Forum: Four stroke
Topic: 4469 piston rebore clearance
Replies: 8
Views: 633

Re: 4469 piston rebore clearance

Are these pistons ok for use with normal modern petrol? I have such a high compression piston plus a barrel,but have been reluctant to fit it because of the high compression ratio.
by volker.halbach
Mon Apr 12, 2021 3:12 pm
Forum: Main Chat Forum
Topic: Square Four Logo
Replies: 15
Views: 1577

Re: Square Four Logo

I only know that mixed-case fonts are not that unusual.
by volker.halbach
Sun Apr 11, 2021 1:41 pm
Forum: Main Chat Forum
Topic: Square Four Logo
Replies: 15
Views: 1577

Re: Square Four Logo

I went to the members area and looked at a few catalogues. The timing covers in the 1957 catalogue show red paint. It looks bright red, not maroon. I know that pictures in the sales literature are not reliable, but I doubt they would have added the extra red if it hadn't been there in the original. ...
by volker.halbach
Wed Mar 31, 2021 2:15 pm
Forum: Four stroke
Topic: Best Paint For HOT Cast Iron Heads
Replies: 3
Views: 342

Re: Best Paint For HOT Cast Iron Heads

In my experience the normal "stove" and "cylinder black" paint flakes off around the exhaust area. I painted my iron head with Mipatherm paint a year ago, because it said "heat resistant up to 800C" on the tin. So far it still looks good.
by volker.halbach
Wed Mar 17, 2021 2:17 pm
Forum: Ariel Talk
Topic: 1937 VB 600 valve chest breather
Replies: 25
Views: 1989

Re: 1937 VB 600 valve chest breather

There are two sizes of Ariel single pumps. Paul's 1937 pump will have a 3/16" bore on the delivery side. This was enlarged to 1/4" at some point after the war. The return side always stayed the same. Waller's book has the exact measurements. The Morgo pump will have an even higher capacity.
by volker.halbach
Wed Feb 24, 2021 10:40 am
Forum: Four stroke
Topic: NH 350 Valve Guide Removal
Replies: 18
Views: 1525

Re: NH 350 Valve Guide Removal

See the thread "valves and guides for NH" I started two weeks ago. Do not assume that all guides and valves are ok. I have new guides that give an interference fit of 0.004" in my cylinder head. Often the materials are not compatible and valves get stuck.
by volker.halbach
Thu Feb 18, 2021 6:24 pm
Forum: Four stroke
Topic: valves and guides for NH
Replies: 37
Views: 3459

Re: valves and guides for NH

Wade, so we both have only the oil pipe to the inlet guide. My NH is also from 37. Summing up, there are at least three possible explanations for the problems: 1. The combination of untreated stainless valve stems with cast iron guides just doesn't work. That seems to be one reason for problems with...
by volker.halbach
Wed Feb 17, 2021 6:50 pm
Forum: Four stroke
Topic: valves and guides for NH
Replies: 37
Views: 3459

Re: valves and guides for NH

Wade, which year is your head? Ariel tried to address the problem of valve lubrication. Of course, from 1934 the heads were semi-closed. The small pipe running from the crankcase to the inlet valve guide seems to do its job. When I removed the inlet guide there was oil in the groove of the guide. In...
by volker.halbach
Sun Feb 14, 2021 8:33 pm
Forum: Four stroke
Topic: valves and guides for NH
Replies: 37
Views: 3459

Re: valves and guides for NH

Nev, I have no aspirations to experiment with reduced clearances. I had asked the G&S guy what he recommends against galling, and he just had never experienced galling with his valves in iron guides, even with these reduced clearances. I had asked about honing the guides or starting with enlarge...

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