Author Topic: RGS vs. SR head  (Read 7314 times)

Offline duTch

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Re: RGS vs. SR head
« Reply #15 on: 21.09. 2012 09:59 »

 Hey Trev,
          I know it's only semantics or a technicality,
Quote
On the under side of the RH port is stamped "RR 177".
but unless I'm more dyslexic than I thought, is the 'RR/RR 177' stamped under the left port.?
  I know, I do it all the time when somethings turned upside down and backwards-  sorry but just like to keep the story straight, ya never know who's listening/watching *smile*

 cheers ,duTch
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

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Re: RGS vs. SR head
« Reply #16 on: 21.09. 2012 23:38 »
Dutch,
           Sorry if I confused you, I was pointing out the markings as viewed.
I have corrected the post to confuse everyone else!

Julian,
            The 1953/5 RR & SS both had the alloy head with the detachable manifold.
The RR used a TT carby and the SS had a 276 in 1954 and a Monobloc in 1955.
Maybe the "special" Daytona heads were only standard heads tricked up for racing.
The heads I have with the date castings are just plain old standard heads of the day, nothing unusual about them. I have seen a few of them, the SS being far more common than the RR here in Australia.
The RR177 head is different as it has no date and enlarged ports.
I bought it at a swap meet some years ago as my 1954 head needs a lot of work.
It is possibly an American import to this country as there has been a lot Aussie entrepreneurs scrounging about the U.S for a lot of years.
The actual part number of the head is 67-1105 for the RR and 67-1101 for the SS.
The SS valves,collars, bottom cup and colletts are the same as the standard engines whereas the RR has the increased diameter collars and cups with colletts to match the groove in the valves.
When you compared the heads for flow, which head did you test - 67-1126, 67-1549 or 67-1571?
Was the 67-1106 head stock standard with small ports and the single carb manifold fitted?
Attached are the RR parts pages from 1955.

Trev.

Offline JulianM

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Re: RGS vs. SR head
« Reply #17 on: 23.09. 2012 09:49 »
Hi Trev,

Yes, I think it was not only possible but quite "probable" that the same casting was used and just "tricked up" as you say.
There are so many conflicting stories about this but if we look at what has just been said it does not take a brain surgeon to realize the 98% probability. They would have been very daft not to do so to be honest!

The head I compared was the Big Valve Rocket Gold Star head with integral manifold. It had been completely reworked and had been opened out to fit a 1 1/2" carb,  (unfortunately I have now sold it so no numbers for you) however it had 38mm inlets and 35mm exhausts.
My 1106 head had absolutely no work done to it at all, "as cast" with 1 " inlet port diameters etc.
The comparison was not to see which flowed best on a single carb but to see if the "myth" was true that you could get no more power from the twin carb head than a good single.  This "myth" looks well busted!

I have since, reworked the twin carb head and matched it to the twin 32mm carbs so it will be interesting to see how that one flows on the flow bench with everything on it.
55 Ariel HS mk1,
58 BSA Super Rocket Scrambler special,
60 BSA Gold Star, Jim hunter desert racer,
64 Norton N15CS,
65 Triumph TR6 SS,
66 Triumph Bonneville,
71 AJS Stormer,
71 BSA Rocket 3,
71 Laverda 750SF,
71 Laverda/Egli 750SF, Race bike,
73 Norton Commando 850,
74 Moto Morini 3-1/2 Sport,
74 Bultaco Sherpa 350,
76 Beta Cross 50,
77 Moto Guzzi Le Mans Mk1,
80 Ducati 900 MHR,

Toby

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Re: RGS vs. SR head
« Reply #18 on: 23.09. 2012 11:28 »
""To be honest it would make more sense if you are correct as making a batch of 200 or so would be a very expensive""

What do you class as, expensive ?
If you are making a large batch of heads then it seems there are two main expenses, the first is to make the pattern, the second is the machining.
A batch of 200 castings could be made in any decent Foundry where they have an automatic sandbox moulder and nowadays with CNC apparatus, once programmed all you have to do is pop in the blank then a bit later remove the machined head.
Unfortunately due to cooling shrinkage you cannot use an existing head as the pattern otherwise the finished casting would be too small.
It's possible to put a coating of resin onto an existing part use it as the pattern and finish off by machining but I am not sure if it would work on heads.

The possibilities are there but you need to have connections with a Foundry plus a well equipped Machine shop.
I shall bear this in mind when visiting the folk I deal with in my work.

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Re: RGS vs. SR head
« Reply #19 on: 23.09. 2012 21:53 »
I have now measured the inlets on the 1106 head and find them to be nominally 15/16" as are the ports in the manifold.
The flange on the manifold has a 1-1/16" bore.

Trev.

Offline JulianM

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Re: RGS vs. SR head
« Reply #20 on: 24.09. 2012 11:22 »
Toby,

I was refering to 1954 when there were no CNCs or even electric calculators let alone computers  ;o)


Regards,
Julian
55 Ariel HS mk1,
58 BSA Super Rocket Scrambler special,
60 BSA Gold Star, Jim hunter desert racer,
64 Norton N15CS,
65 Triumph TR6 SS,
66 Triumph Bonneville,
71 AJS Stormer,
71 BSA Rocket 3,
71 Laverda 750SF,
71 Laverda/Egli 750SF, Race bike,
73 Norton Commando 850,
74 Moto Morini 3-1/2 Sport,
74 Bultaco Sherpa 350,
76 Beta Cross 50,
77 Moto Guzzi Le Mans Mk1,
80 Ducati 900 MHR,

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Re: RGS vs. SR head
« Reply #21 on: 25.09. 2012 03:10 »
Isn't this beautiful?  *smile*

Trev.

Online bsa-bill

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Re: RGS vs. SR head
« Reply #22 on: 25.09. 2012 09:50 »
always learning on this forum - I now understand the term "Overhead valve" *yeah*
All the best - Bill
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1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline gavinoz

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Re: RGS vs. SR head
« Reply #23 on: 25.09. 2012 10:20 »
Actually its the legendary "Reverse Head": it sucks smoke and stuff in, and produces clean air and refined hydrocarbons out the carburettor.
Rigid A7S, 57 A10 in pieces
Australia

Online Brian

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Re: RGS vs. SR head
« Reply #24 on: 25.09. 2012 10:57 »
You need one of them on your tractor Gav, then you wouldnt have to give it a cigarette and then shoot it to get it to start. ???

Online bsa-bill

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Re: RGS vs. SR head
« Reply #25 on: 25.09. 2012 11:25 »
Quote
You need one of them on your tractor Gav, then you wouldnt have to give it a cigarette and then shoot it to get it to start.

Hi Brian - now I've heard about the cartridge starting technique from the old guys I worked with, so either you have some very old gear out there or your lying about your age *roll*
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online Brian

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Re: RGS vs. SR head
« Reply #26 on: 25.09. 2012 11:36 »
I grew up on a farm and we had one. I'm pretty sure the tractor in Gav's pic is a Field Marshall.

Better not say much more about this or we will get accused of comparing A10's to tractors *eek*

Offline JulianM

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Re: RGS vs. SR head
« Reply #27 on: 26.09. 2012 08:13 »
I like the light weight cylinder block underneath it but am not impressed with how much that gasket is sticking out!  ;) ;)


Trev, I have another 1 3/16  TT carb on the shelf,  wouldn't you like to fit a pair?   ;)

Regards,
Julian
55 Ariel HS mk1,
58 BSA Super Rocket Scrambler special,
60 BSA Gold Star, Jim hunter desert racer,
64 Norton N15CS,
65 Triumph TR6 SS,
66 Triumph Bonneville,
71 AJS Stormer,
71 BSA Rocket 3,
71 Laverda 750SF,
71 Laverda/Egli 750SF, Race bike,
73 Norton Commando 850,
74 Moto Morini 3-1/2 Sport,
74 Bultaco Sherpa 350,
76 Beta Cross 50,
77 Moto Guzzi Le Mans Mk1,
80 Ducati 900 MHR,

Offline a10gf

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Re: RGS vs. SR head
« Reply #28 on: 26.09. 2012 18:41 »
Isn't this beautiful?  *smile*

Yes!

A10 GF '53 My A10 website
"Success only gets you a ticket to a much more difficult task"

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Re: RGS vs. SR head
« Reply #29 on: 26.09. 2012 22:15 »
Julian,
             Mine is only 1-1/16" so they wouldn't match.
It would upset the rivet counters too!

I thought for a while that I had accidentally posted on the comedy forum!  *smile*
Speaking of tractors, hasn't Harley Davidson already won that title?

Trev.