2 cams look the same but one isn't a ramp cam

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Ian.Taylor
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2 cams look the same but one isn't a ramp cam

Post by Ian.Taylor »

At first look these are 54 & later VH cams.
Not so, The one on the left is out of my 1 owner 53 VHA ( built in Oct 52) the one on the right is from a 54 VH.
Both should be ramp cams by the looks of them but the Left cam is not and requires Nil & 002.
If set to 006 & 008 like I did in the early 90s , it is very noisy ! , it likes Nil & 002 and I have been using that clearance since..
The only difference I can see is the letter A on the end of the shaft on the right Cam.
Just curious if the letter A indicates a ramp Cam that Ariel used to help identify the cams with the same machining method.?
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Re: 2 cams look the same but one isn't a ramp cam

Post by Roger Gwynn »

I am not aware of any different single lobe cams other than the HS ones, it is possible it has been re-ground to the earlier profile at some time.
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Re: 2 cams look the same but one isn't a ramp cam

Post by Simon.Gardiner »

Ian
Single lobe cams: 1951 - no ramps. 1954 -same profile but with added ramps for the alloy head VH (NH still had the iron head and presumably still had the non-ramp cam.)
The ramps are for 'quietening' , I imagine if you've splashed out for a rorty 'competition' alloy engined VHA or VCH in 1952 or 1953 you're not worried about a bit of cam clatter and there's no reason for the works to come up with a special cam just for you??!
See also Paul Jameson's 'The definitive Article on Ariel cams' in the on-line library, in 'Miscellaneous' :
http://www.arielownersmcc.com/members_o ... aneous.htm
(Paul, I know it's not been 18 years yet but as we've since discovered the VCH cam isn't it time for another article update 8-) :twisted: )

Dunno about the 'A' stamping, I think you might be right but somebody somewhere will probably find a ramped cam that doesn't have an 'A' on it
(as Paul quotes, 'The only thing you can be certain about where Ariels are concerned is that you can’t be certain about anything where Ariels are concerned'.)

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Re: 2 cams look the same but one isn't a ramp cam

Post by Ian.Taylor »

Roger Gwynn wrote: Wed May 03, 2023 9:20 am I am not aware of any different single lobe cams other than the HS ones, it is possible it has been re-ground to the earlier profile at some time.
The original owner bought it new from McBrides in Toronto and the family put the VHA in the
barn in 1961 after he passed away.
There it sat until 1977 when I bought it..
I doubt it had any work on the motor, still had the concave std piston in it.
He used it mostly for field use on the farm.

I just find it odd this cam requires nil & 002 although it looks like a ramp cam.

My thought was Ariel just changed their machining methods sometime in 52 and the letter A on the 54 Cam indicates a ramp cam.
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Re: 2 cams look the same but one isn't a ramp cam

Post by Ian.Taylor »

Simon.Gardiner wrote: Wed May 03, 2023 12:57 pm Ian
Single lobe cams: 1951 - no ramps. 1954 -same profile but with added ramps for the alloy head VH (NH still had the iron head and presumably still had the non-ramp cam.)
The ramps are for 'quietening' , I imagine if you've splashed out for a rorty 'competition' alloy engined VHA or VCH in 1952 or 1953 you're not worried about a bit of cam clatter and there's no reason for the works to come up with a special cam just for you??!
See also Paul Jameson's 'The definitive Article on Ariel cams' in the on-line library, in 'Miscellaneous' :
http://www.arielownersmcc.com/members_o ... aneous.htm
(Paul, I know it's not been 18 years yet but as we've since discovered the VCH cam isn't it time for another article update 8-) :twisted: )

Dunno about the 'A' stamping, I think you might be right but somebody somewhere will probably find a ramped cam that doesn't have an 'A' on it
(as Paul quotes, 'The only thing you can be certain about where Ariels are concerned is that you can’t be certain about anything where Ariels are concerned'.)

SG
Who knows for sure Simon , I just find it odd this original cam to the VHA , built in Oct 52 had a cam that looks like a ramp cam for late 53 VHs.
A good friend Big Jim Hunter stopped by in 1990 when I finished the bike , he suggested I had the wrong valve clearance of Nil & Nil. He helped set the valves to 006 & 008.
Upon starting the bike it rattled & clacked so badly he said shut it off !! Back to Nil & Nil and the VHA ran fine....I guess it isn't the ramp cam then he noted.

I still think the "A" indicates a ramp cam How else would you tell the 2 apart.
My other thought was sometime in 1952 Ariel changed their machining of the cams.
The owner bought the bike new in 53 from McBrides in Toronto, rode it then in the last few years it became a field bike on the family farm.In 1961 when he passed away the family pushed it into a barn and there it sat until 1977 when I bought it, still had the std concave piston.
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Re: 2 cams look the same but one isn't a ramp cam

Post by Vincent.vanGinneke »

what would be the timing on a VCH cm ? same as a HS Mk3 ?
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Re: 2 cams look the same but one isn't a ramp cam

Post by Roger Gwynn »

The VCH and VHA are listed as having the standard 1750-51 cam in 1953, which should be a forged cam (no hole through the lobe) and without ramps, the ones in the picture both look like 1750-54 cams which should have quietening ramps. It is always possible that a late VHA could have had one of the new type of cams that had been machined to the old profile to avoid confusion when setting the tappets, some 70 years later! Just noted that you said it was built on October 1952 so that shoots that idea down. I've not come across this before but then I don't check all the cams that I come across or are sent in for exchange.
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Re: 2 cams look the same but one isn't a ramp cam

Post by Simon.Gardiner »

Vincent.vanGinneke wrote: Wed May 03, 2023 4:13 pm what would be the timing on a VCH cm ? same as a HS Mk3 ?
Apparently very similar see David Anderson's very comprehensive analysis! 8-)
viewtopic.php?p=87951&hilit=vch+cam#p87951

Ian - I'm assuming you know one is a ramp cam 'cos you can see the ramps? That's how I tell them apart. (I don't trust any other markings.)
1952-53 Owners Handbook for singles:
VH, VHA , NH with standard cam assembly Nil/.002
NH, VH, VHA, VCH series B engines (from June 1953) cam assembly 'R' type, identified by an 'R' after the engine number, .006/.008

Interesting, I don't think I've seen a set of crankcases with an 'R' suffix, and it looks like even the iron-head NH got the 'ramped' cam.

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Re: 2 cams look the same but one isn't a ramp cam

Post by Vincent.vanGinneke »

few years ago I bought an new 'VCH' cam, made by Newman cams for the AOMCC.
Have not fitted or used it yet but plan is to fit it in my WNG engine that already has a steel crankshaft and decent ratio piston in it.
yes, one of those projects :) ..... :lol:
picture shows it together with a 'A' single lobe cam.
should be fun....
VCH - VH camshaft  (1).JPG
VCH - VH camshaft  (2).JPG
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Re: 2 cams look the same but one isn't a ramp cam

Post by will_curry »

I have six single-lobe cams. Three have the letter A and three don't.
All six have a hole bored through the lobe as in the right-hand cam
in Vincent's post above.

Measuring across the flanks of the lobe - the base circle - of the A
cams gives a value of around 1.015". The corresponding value of
the unstamped cams is around 1.000".

I had understood that the nil and 2 thou clearance worked with
all-iron motors with iron pushrods and also with all-alloy motors
with alloy pushrods like VHAs. Those later singles with an alloy
head and iron barrel with alloy pushrods needed 6 and 8 thou to
allow for the differential expansion of the iron barrel and the
alloy pushrods.
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