BSA A7 Dual carb inlet manifold spacing?

[Sluggo]

Might seem an odd question, but does anyone have access to the measurements for a dual carb manifold or cyl head?  BSA A7 apparently.

Heres the problem.  I WON a ebay auction for what I *THOUGHT* was a dual carb manifold for a Triumph preunit 1950s TR5 or T100 alloy head.  They made a race kit and the origininal manifolds are highly sought after, although, there is 2 guys making replicas for these and the TR6 single carbs to be dual carbs.
the difference is, on a TR6 the studs are 12 oclock and 6 oclock, on the TR5 and T100 alloy heads (Close pitch fins, I can post a pix) the studs are 11 oclock and 4 oclock left side and reversed on right to 1 & 7.  Small ports as well being the T100 is a 500 twin.

Now I am being told the manifold is actually for a BSA A7,, the ones with the seperate manifolds.  I will post a picture and my measurements for the T100 Triumph head, as I have a very rare 1953 T100C. 

But I am wanting to know how different they are BSA-Triumph.

For measurement purposes, lets do this. Center to center the following.  L-R top bolts/studsts, CtoC.  L-R bottom bolts-studs.  Center to center top and bottom bolts/studs on each port. And ID Port dia.

I will do the same on the Triumph.  As well I will check some other manifolds I have,,( 2 into 1, some I know are unit Triumph 500, but theres a couple mystery ones.

Many thanx in advance, and more soon.

For reference.. See: https://www.ebay.com/itm/134024781393

[bikerjohndavies]

Hi,
Just so you get the correct answers, the manifold is from a long stroke A7 Star Twin of 1949/50 vintage that had a pair of 275 pre-monobloc's fitted. The ports on the head are the same for both single and twin carb setups except the Start Twin head has recesses cut in them to match the lips on the manifold where as the standard single carb version didn't.

[Sluggo]

Ohhh dear!  Apparently its unlikely that manifold will fit mine,, being a Triumph and all,, I do have a early rigid A10 on the back burner but I will be running a "HotFlash" setup on it. (Later alloy head, and other bits).

But im paying the Feebay seller and perhaps we can find the manifold I bought a new appropriate home, 

I spent a bit of time in storage and sorting parts,  Heres a picture of the Triumph Tr5-T100 alloy head (Close pitch fins, this one is a 1953 T100C). I looked at manifolds for later unit Triumphs, BSA A65, and early Norton Twins. Still have some mystery manifolds,, One is marked Kawasaki although not sure what model.

The ones shown here on the table, the middle 3 are correct for early Preunit Triumph close pitch ally heads. The bolt/stud hole spacing on them is 2" center to center and 4" CtC, the ID of the holes/ports is 1" inch

I have yet to ID the manifolds on the left,,(Any ideas?)  and the ones on the far right. 

[Sluggo]

Here is a Image of the reproductions on Ebay, this is for the Triumph preunit close pitch fin alloy heads, which typically use a manifold to go 1>2, but the race kits setup allow twin carbies.  So, this wont fool anyone but appears nicely made.  They retail for $199 from Steadfast cycles, and there used to be someone else making them but I dont see them listed anymore.  I can make my own,, and 200 beer slips is a lot of money, But you factor in time and labor,, Im not sure its worth the time to make my own,,

They make them for later Triumphs as well (TR6)  If anyone wants to discuss rare and obscure dual carb Triumphs on early preunits, We can do that elsewhere or off list. I do have some knowledge and adding to it, but have several early preproduction dual carb Triumph heads and 2 Delta Heads for Preunit 500s, the Race shop fitted them as well as a limited number were sent to US Distributors, 250 to East Coast TriCor and 250 to West Coast JoMo, also known as Johnson Motors.

My Delta heads are fitted to a 1958 TR5 Desert Sled and a 1956 T100., Some unique issues about them, but way off topic for a BSA Board,,,

in the interim,, The oddball BSA Dual carby manifold will be shipped to me, I will trade or sell it to a appropriate adopter, no flippers or resellers. But I am in need of a manifold for my 53 T100C.

[Rocket Racer]

just fyi the later alloy heads (both A7ss and a10RR) have common stud spacing with a 2:1 manifold as std. I only have the A10RR manifold as attached, my other alloy twin ports run custom manifolds for twin carbs.

The alloy BSA head has the bottom studs closer together, approx 5cm centres and the top studs approx 10.5cm

[Sluggo]

I did actually receive the part, and it is INDEED intended for a BSA. Not a Triumph.  I have since tried and failed to buy a factory race manifold for the Triumph project and simply, too few out there and when you do find one or the race kit parts they are prohibitively expensive.  However I found a guy making repop- copies and very reasonable prices so going that route.

A new - funny wrinkle is I went into storage looking for my cast iron heads as I knew I had several,. I also knew I had a 500 cast iron top end, and actually had offered it up here with no interest.
  Funnily enough, the cast iron 500 head and cyl is actually a long stroke A7 that uses this twin carb manifold (Color me surprised)
So, I cleaned up the cyl, I have some old shop inventory of pistons and rings and nows a good time to sort and label them all.  Maybe I even have pistons. Dont know.  Ill do a mock up and post some peektures here in next few days,

But been busy with other issues and a family issue.  But something soon.
In the meantime, just an update and thanks especially Rocket Racer. & Biker John Davies for your help!

[Sluggo]

BTW, while on the topic, I am getting one of the T100 motors (I have several All alloy 500 Triumph Preunits)
ready to display at a show with some racing and period custom bling.
IE: Religious accouterments   As in Holy,.  as in Someone got a drill press for Christmas and went crazy.
So, the 53 T100C and the later RR Model T100 are being built as period custom race bikes.,

So the guy I ended up ordering the intake kit from, Deserves a shout out,,, really nice stuff. Wont make the rivet counters or the OCD Bolt polishers happy, But sure is some cool stuff and great prices.
His ebay account is ZanewillCamille, and he makes some really nice bling.
See: https://www.ebay.com/sch/zanewillcameille/m.html?item=234388567371&rt=nc&_trksid=p2047675.m3561.l2562

This isnt BSA, but hopefully the mods forgive me and on the topic of dual carbies, maybe he can help out the BSA Community if theres interest?   These are some sample photos to show off his parts, NOT MINE,, But shows similar to what I am going for.  I have several different carb combos I am mocking up but not sure until they show up. (Chopped Mono blocs with remote float,, or Handed L & R mono blocs with extended bowls.)
But His samples sure are sexy, dont you agree?