Triple SU

[D-MAN]

Just picked these up and really want to use them on the next project

I ran twin SU on my old FB and had them in several “shops” but could never end up getting them to to run right... had so many issues I ended up going back to a single stromberg

So I am concerned that I’ll have the same problem with triple SU

So question is does anyone know of anyone running triple SU’s on their FB or EK or a shop that you can recommend (I’m in Sydney)

[D-MAN]

Here is my old twin SU set up

[Errol62]

Plenty people running them on reds, but greys? I would try the Torana forum. There has been plenty of discussion on there.


FB ute fixer upper, EK van on rotisserie

[Brett027]

I ran tripple SUs on a 179 and then later a 202. Keeping them tuned was a bit of a task but there were a few things that needed to be right. The first is linkages. If your linkages have any play or slippage it becomes seriously hard to keep them in sync. Secondly, if the throttle shafts are leaking air because the bushes or shafts are worn, it will be very hard to keep them in sync. Fuel: SUs are different because they are variable jet and variable venturi. So from idle to full throttle, the position of the jet at idle will impact fuel flow all the way to full throttle. To set duals/ triples, the jets need to all be at the same starting point(idle). Again, differing wear in the jet/throttle mechanism between carbs will make it hard to ensure they all move the same amount. In order to set the mixtures of each carbie I used a see-through spark plug. You could see the colour of the burn for each pair of inlets/each carb. This is a great bit of gear and if you can get one you won't regret it. I've still got mine. The final bit is air. The SU design effectively changes the size of the venturi depending on engine vacuum. The piston that does this is connected to the metering jet needle, so as the piston rises, more air and more fuel is available. The needles also need to be in a similar state. There is an oil damper that needs the same viscosity of oil in each of the carbs, and there are also colour coded piston springs that are designed to suit particular engine capacities. To keep the carbies in sync, the needles, oil, springs and piston fit all need to be similar across carb. To get multiple carbs delivering the same volumes of air, I used a flow meter that fitted over the carb intakes. Clever people are able to use a piece of hose and listen to the noise to do the job, but for me the flow meter was easy and reliable. So, in essence there is a lot to play with and therefore a lot of variables. If you get it right though they are fuel efficient, responsive and make a lovely noise when you put your foot down. Beware of well worn tripple SUs 'cause you will require lots of money and time to get them sorted. Harv has put some great info together on SUs.

[Harv]

Triple SUs work fine on a grey - ask Warren Armour .

SUs are a very, very simple carb. Once set, they rarely go out of tune other than by linkage slippage. Being simple though, any change you make affects the entire throttle range (unlike Strommies, which have almost independent circuits for idle, acceleration, cruise and power).

Two options:
a) learn a lot about Strommies from a reputable source, probably not forums, then set them up yourself. I've got a decent SU book or two that you are welcome to borrow (including Vizard's awesome advice on tuning/modification) if you want to go down that path.
b) take them in to the Carburettor Service Company at Strathfield. They have set up more SUs than I've had hot breakfasts.

You can also get parts from SU Midel out near Canterbury, but I've found their advice is hit and miss... depends on who is on the counter. There are days when the Fabre go-fast parts side of their business is a lot busier.

Cheers,
Harv

[D-MAN]

Thanks Guys

Cheers Harv will take them out to Strathfield as my old set was set up by SU midel and I think that was the initial problem

[funkyscooter]

Clever people are able to use a piece of hose and listen to the noise to do the job, but for me the flow meter was easy and reliable.

Great info Brett. I was one of those clever people with a hose. But also dumb I guess as I had no idea what a flow meter was at the time. Recently I put twin webbers on my Karmann Ghia. Flow meter (snail) is the only way to set those up.

I have had twin SU's on a car and they were great, simple to tune and service. But the triples I had on the 202 in my EK were always just a bit off. Still dont think I had the right main needle, but they work well enough for me to leave them. Would lose dampener oil to the point where I kept a bottle of sewing machine oil in the boot. And they do make a great sound!

Keep us posted D-MAN, I'm on the fence at the moment with the SU's. Was thinking about going triple webbers if I can get them to fit. At the moment there is a box welded into the firewall for the triples. I was going to delete it as a part of the rust repairs but might rethink it.

[EK JAY]

My mate had triple SU's on his Hr sedan 186 red motor It used to fry tyres at will but he was for ever tuning them and ended up taking them off and swapped them for twin stromies which he still had to tune but not as often as the Su's
Also need to modify the fire wall as the triples won't fit
Jay

[D-MAN]

My mate had triple SU's on his Hr sedan 186 red motor It used to fry tyres at will but he was for ever tuning them and ended up taking them off and swapped them for twin stromies which he still had to tune but not as often as the Su's
Also need to modify the fire wall as the triples won't fit
Jay

Really want to run triples as I love the look of them
Firewall is another issue ...

[Errol62]

Depending on the manifold you can get away with minor dint. Trev did so in his chopped fb wagon.


FB ute fixer upper, EK van on rotisserie

[Brett027]

This is the see through spark plug I referred to. Invaluable for mixture adjustments on SUs. Available for different hole sizes. Good for your mower too On Ebay for about $80.

[D-MAN]

This is the see through spark plug I referred to. Invaluable for mixture adjustments on SUs. Available for different hole sizes. Good for your mower too On Ebay for about $80.

Thanks Brett

[funkyscooter]

So too a trip down memory lane and got the carbies out to have a look. Also took a couple pics of the box in the firewall. Looks like overkill but the SU still managed to knock against the firewall after the engine rebuild. Maybe new engine rubbers had it sitting a little higher. 3 fuel filters seems like overkill! Must have had an issue with dirty fuel. That regulator (set at 3.5 psi) is a death trap. Had one of those on the Karmann and it started spewing fuel everywhere.

[Errol62]

That’s pretty crude. I’m sure you will improve it now you have the patience that comes with “maturity”.


FB ute fixer upper, EK van on rotisserie

[funkyscooter]

Yeah its ugly as and a great little spot for fuel to pool up in the event of a failure. Done before my time.