Iron Vs Alloy head exhaust port angle

[gavinoz]

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.

[duTch]

 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 @ ~40º ('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 )

[bikerbob]

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.

[muskrat]

G'day Gav.
The SS pipes I had made for my 51 A7 plunger fitted when I swapped over to an alloy head.
Cheers

[Kickaha]

I swapped my 55 A10 iron head to an alloy head and used the same pipes without any modification

[bodger]

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.

[Rocket Racer]

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 

[bodger]

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!

[bodger]

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.

[Greybeard]

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.

[Rocket Racer]

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

[bodger]

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...

[Rocket Racer]

the sand only goes in the pipe, not the engine and its dry. I believe its usual  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.

 

[muskrat]

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

[bodger]

sorry Rocket, I was clowning about the about the sand, but you never know on the internet....

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!