Author Topic: Iron Vs Alloy head exhaust port angle  (Read 954 times)

Offline gavinoz

  • A's Good Friend
  • ***
  • Join Date: Apr 2012
  • Posts: 139
  • Karma: 3
  • Dogs & Sheep hate smokers worse than Hondas.
Iron Vs Alloy head exhaust port angle
« on: 25.03. 2016 01:37 »
Hi all. I am getting some (non standard) pipes made up for my s/a project. I read Q & A between dUTCH and trev , but just wished to confirm: Is there any difference in heights and exhaust port angles, between the alloy head and the iron head? My exhaust maker has an iron head s/a Flash to template from, but I am using an alloy head, so would like to know if this a straight forward template. Cheers, from Gav.
Rigid A7S, 57 A10 in pieces
Australia

Offline duTch

  • Ricketty Rocketty Golden Flashback
  • Wise & Enlightened
  • *
  • Join Date: Oct 2011
  • Posts: 4538
  • Karma: 41
Re: Iron Vs Alloy head exhaust port angle
« Reply #1 on: 25.03. 2016 06:41 »

 Hiya Gav, I have an ally head on my '52 Flash (Plunger), so any measurements I have will likely be diffo fro a S/A jobbie, so probably can't be helpful. Most I can recall from that was the angle I determined @ ~40ยบ ('citation' needed)

 The pipes I have were new, but kinda crap really (bought them from someone sharp I won't name), but I made them work (too long at the port exit, then wrong radius bend/straight/bend *pull hair out*)
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

Offline bikerbob

  • Resident Legend
  • *****
  • Join Date: Feb 2011
  • Posts: 583
  • Karma: 8
Re: Iron Vs Alloy head exhaust port angle
« Reply #2 on: 25.03. 2016 09:07 »
The part numbers are different for the A7 S/A and the A10 S/A but they are  the same for both the alloy and Iron heads. Also the exhausts are different for 1954/57 S/A and 1958 S/A onwards. BSA changed both exhausts and silencers in 1958.
56 A7 s/a
63 A65

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8920
  • Karma: 113
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Iron Vs Alloy head exhaust port angle
« Reply #3 on: 26.03. 2016 04:54 »
G'day Gav.
The SS pipes I had made for my 51 A7 plunger fitted when I swapped over to an alloy head.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online Kickaha

  • A's Good Friend
  • ***
  • Join Date: Apr 2014
  • Posts: 163
  • Karma: 6
Re: Iron Vs Alloy head exhaust port angle
« Reply #4 on: 27.03. 2016 10:07 »
I swapped my 55 A10 iron head to an alloy head and used the same pipes without any modification
1956 BSA Gold Flash
New Zealand

Offline bodger

  • Moving Up
  • **
  • Join Date: Mar 2016
  • Posts: 16
  • Karma: 0
Re: Iron Vs Alloy head exhaust port angle
« Reply #5 on: 27.03. 2016 12:45 »
Hi, good dang question I was asking meself tonite looking at exhausts from several online suppliers.

Some have nice bends the way they should be, some seem done with an electrician's conduit bender.

Thanks for the info, I have both iron and alloy heads for an A7 SS 1952iish

Does anybody know the source for the really sweet flat track pipes that swoop around to the left side with the short reverse cone meggas on them? Mine had been raced but came with stock exhausts only.

These were seen on twins all thru the early 50's into the 60's at flat tracks in the US.


Offline Rocket Racer

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 1546
  • Karma: 16
  • A kiwi with a racing A10 rig and too many projects
    • NZ Classic Sidecar Racing
Re: Iron Vs Alloy head exhaust port angle
« Reply #6 on: 28.03. 2016 01:36 »
You mean this style? (Pics 1 &2), I have seriously thought about it
Luckily I have access to a very clever engineer who makes sand bend pipes with lovely curves .
He made me a nice set of 2:1 as the repro's I got out of the uk didnt quite fit  *evil*
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline bodger

  • Moving Up
  • **
  • Join Date: Mar 2016
  • Posts: 16
  • Karma: 0
Re: Iron Vs Alloy head exhaust port angle
« Reply #7 on: 28.03. 2016 12:49 »
Ah, that's it, and haven't seen them advertised ever, not even in BSA race kit flyer repros...yet they were on all the flat trackers of the time I saw in photos for many years.

This is an A7 flat tracker restored by I am not sure who or where I got the pikkies from, but what a beauty...now all it needs is some dirt!


Offline bodger

  • Moving Up
  • **
  • Join Date: Mar 2016
  • Posts: 16
  • Karma: 0
Re: Iron Vs Alloy head exhaust port angle
« Reply #8 on: 28.03. 2016 13:12 »
Are those the repro pipes?....So Shiny!...So Chrome!

I did just see a set of A7 pipes in the Swiss Bsa part place..wossname?...anyway..did you send the pipes back?

 Sand bending pipes sounds like one of those basic brit bike skills out of one of my ancient mc repair books..I must try it asap.

Online Greybeard

  • Jack of all trades; master of none.
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 7329
  • Karma: 40
Re: Iron Vs Alloy head exhaust port angle
« Reply #9 on: 28.03. 2016 15:11 »
I once got involved with frame tube bending for a mate who was building a kneeler outfit. I suggested filling the tube with well compacted dry sand, (from a fire bucket actually) before heating and bending. It seemed to work well. I imagine that exhaust pipes could be bent the same way.
Greybeard (Neil)
1955 Golden Flash, sprung frame
Supporter of THE DISTINGUISHED GENTLEMAN'S RIDE https://www.gentlemansride.com

Warwickshire UK


A Distinguished Gentleman Riding his 1955 Plunger Golden Flash

Offline Rocket Racer

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 1546
  • Karma: 16
  • A kiwi with a racing A10 rig and too many projects
    • NZ Classic Sidecar Racing
Re: Iron Vs Alloy head exhaust port angle
« Reply #10 on: 28.03. 2016 21:16 »
Graybeard, you're onto it! dry sand... I can't take any credit for such a talent, I've just seen the results. Nice smooth bends with constant radius.
Buying this stuff off the shelf from a supplier in another hemisphere is just a recipe for disappointment. Not so bad if you live just up the road. So excepting mufflers it pays to have em made to fit...then chromed

I do love those pipes and that semiunit motor looks so hot in that flat track trim.

I might just have to upgrade my zorsts on the sidecar

A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline bodger

  • Moving Up
  • **
  • Join Date: Mar 2016
  • Posts: 16
  • Karma: 0
Re: Iron Vs Alloy head exhaust port angle
« Reply #11 on: 28.03. 2016 22:16 »
Dry sand bending is referenced in the pre fifties books and pamphlets I have seen, it will be interesting to try it!
 
 So, yes THOSE are the pipes I am looking for, I am trying to figure out where I saw that and ask the photographer/owner etc...so if anybody sees such....

I may need advice about getting the sand back out of the engine tho... *eek*

Offline Rocket Racer

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 1546
  • Karma: 16
  • A kiwi with a racing A10 rig and too many projects
    • NZ Classic Sidecar Racing
Re: Iron Vs Alloy head exhaust port angle
« Reply #12 on: 28.03. 2016 22:44 »
the sand only goes in the pipe, not the engine and its dry. I believe its usual  *dunno* to weld end plates to keep the sand captive, then remove them once you're done. So no sand should end up in the motor.

 
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8920
  • Karma: 113
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Iron Vs Alloy head exhaust port angle
« Reply #13 on: 29.03. 2016 00:37 »
I was shown how to do it as a 15yo. Done it a few times making pipes for my chook chasers (trail bikes). Heating the outside of the bend more than the inside. I've also used pieces of mandrel bent pipe welded together to get many bends in a short distance.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline bodger

  • Moving Up
  • **
  • Join Date: Mar 2016
  • Posts: 16
  • Karma: 0
Re: Iron Vs Alloy head exhaust port angle
« Reply #14 on: 29.03. 2016 09:54 »
sorry Rocket, I was clowning about the about the sand, but you never know on the internet.... *eek*

That A7 was sold at Mecums Auctions a few years ago and was made/restored by Dick Mann...so I was told.

It doesn't get more authentic that that!