Home made Header, right hand drive Model A

Hi
I thought I might share some photos of my home made header for my right hand drive Model A.
Brendan

 

Note the collector tacked to the engine stand.
Just a matter of running the 1/12 tubes from the flange to the collector

 

Brendan, nice job. Your headers are looking good. Now you need to show us the rest of your project.

................Jack

 

This is my first attempt at Tig welding, so my welds are not very pretty, it is very much like oxy welding.

 

cool!

 

Well here it is, started life for me as a rusty wreck.

 

Now can I make these SU carbs fit?

 

The SUs won't be a problem after those headers - make a log manifold. I guarentee that the engine will idle nicely with whatever needles are in there.

To get it running right you need to look for a needle used in a standard application that is broadly similar to your engine in terms of cylinder size, rev range and power output. See where that leaves you in terms of driveability and engine performance and then it is a matter of fine tuning by fiddling with needles (to get the right station sizes), dashpot oil and springs. The Des Hamill book is very good and there's a website called mintylamb which is very useful on needle comparisions.

Burlens are your go to guys for needles, spares and rebuild kits.

There are a couple of relevant threads on here with HAMBers fitting SUs to sixes and V8s.

 

Thats a great Model A, and the headers will be a nice addition.
Heres something else you may like.

http://www.macsspeed.com/dress_up_gear.html

 

Nice job, Brendan. My A needs a header. Never thought of
Using wood for mockup tool. Thanks for the post.

 

The tubes are hard to hold for cutting so I drilled 2 inch and 1/2 holes in a piece of pine frame then cut it long ways so it clamps the tube for cutting.
Brendan

 

I'd looked at doing a header for the Fordor as it's RHD. Trouble is it has a B engine with the fuel pump to contend with too.
I run a single SU myself although I've just stolen the whole engine for the Tourer...

Getting the SU's close enough to miss a bonnet side and fit a filter will be a challenge. Not so if you don't run bonnet sides of course!

 

What size is your SU? I had an mg expert look at my two inch and 1/2 carbs he says they will be to small for the 200 ci banger?

 

I run a single 1-1/4" SU downdraft on a B banger. 110CFM. Ported, shaped valves and seats, good cam, Thomas head. I've run a 94 and although it was better at the top end it was far too rich at the bottom end. I will play with carbs again but we've just rolled down to Le Mans and back running the little SU just fine. I've a pair of the downdraft 1-1/4" I want to try and also a single 1-3/4".

Let's say 200ci x max 3000revs/3456 x 0.7 volumetric efficiency - which would be pretty good for a flathead banger. I make that around 121.5 CFM. Higher revving - say 4000 and efficiency at 0.75? Maybe 173 CFM.

A single 1-1/2" SU flows around 133CFM and a 94 is around 150CFM.

You're two 1-1/2" will be plenty.

 

Brendan, nice roadster. Thanks for posting more pix , it's good to see another aero modeler on the board. I've got more than a few hanging in my hanger.
Good luck with your projects.

...............Jack

 

Thanks Monkey biker
I thought the SUs would have to remain Garage art.
Now I will press on with the manifold, The MG expert did tell me my carbs are in resonable condition, I will just need to come up with a linkage and one of the levers on the butterfly appears to be wrong.
Brendan

 

For your next attempt , weld only the tube to the inside of the flange and then use a silicone/bronze tig rod on the outside of the flange as that will give strenth but not cause the tube to become brittle and crack.

 

Your Header is looking good!! About time you did something with the flange

 

looks COOL!

 

Some progress made, intake manifolds and linkages fabricated. I think I should have got a Tig years ago.
Brendan

 

Nice work.

A lot of the twin SU installations on minis etc. have a heat shield between the fuel bowl and the header. If you have problems with fuel getting too hot, you could look at the stock heat shield type setups.

Mart.

 

Very clever!

 

I had beeen wondering about the heat, as the front carb bowl is close to the header tube.
I dont have the insulating spacers between the mainifold and the carbs, are they required?
Brendan

 

Hi Brendan....Your choice of SU's is great ...they would the most under rated carby in the world...very simple how they work...the only thing with them is to make sure that the throttle shaft bushs are in very good condition ...you might have to make heat shields for the fuel bowls.....the pair of 1 1/2" is a good choice......I made up a similar header /manifold set up but used Holden Stromberg's off a 202 which is correctly jetted with no messing around....have a look in my albums there are some photos there in the red T trackster......Doug

 

OK Su experts
I have fitted my su carbs, it seems to run strong, how ever the carbs seem to open differently, the front carb opens more than the back. I suspect lack of vacuum on the rear cylinders, Hopfully the video will show the problem.
Brendan


http://www.youtube.com/watch?v=Bm8SqRLVGTM&feature=youtu.be

 

Sorry can't help with the carb problem, but I had to say that's a fine looking A, good work man.

 

Thanks
I am trying to give tis an Aussie flavour, I know SUs are not common for an A.

 

Few things to try:-

Check the springs are roughly the same rate. Swap 'em over from one carb to the other to see if it makes a difference.

Check there is enough dashpot oil and it's the same viscosity.

Check the dashpots move easily - try swapping them between carbs. HS4 carbs have the sprung needle so you don't have to worry about centring the jet. Check the front dashpot isn't modified for "quick lift" (holes in the underside).

Most twin SU setups have a balance pipe in the manifold which always looks a real hinderance for flow - it's probably to make the carbs behave themselves. Go for a blast and do a plug check I reckon.

 

Super cool !!!

4TTRUK