I plan to order an S&S D turbo alcohol carb. From their
catalog, they have problems with the needle and seat as well. I
already use a small scavenging pump to return the fuel so this is not a
big problem. Any advice when it comes to any mods required
to the carb Do I really need to convert to a dual cable
setup If so, is there anyone making a 1/4 turn 2 cable
grip Is there a better seat that will get me above 3PSI fuel
pressure I would also like to know if anyone has used an
adjustable jet, like the thunder jet with methanol.
This will be my first S&S, so any ideas that could save me some time and making a big mistake would be appreciated.
pmfr makes a nice push/pull throttle set up. well worth the investment. but any of the major catalogs have comparable throttles as well. as for 3 psi at the needle and seat, plumb the carb/fuel line with a return and an adjustable bypass regulator. i help on a top gas harley and we have this set up and it works well. you can use whatever pump you want to, regulate the pressure to the carb w/ the bypass. carb will never starve and the excess is routed back tot he tank. one last thought, make sure you get the racing needle and seat. it has cut outs on the side and allows fuel to flow quicker/easier to the needle (effectively deeper in the bowl).
You might want to give Tom Bradford a call about the needle/seat. He makes a needle/seat that will handle up to 5psi. Don't know if it is alky compatible. He's at Hal's PA now: www.halspa.com, (800) 966-4443. He also makes a large capacity float bowl, as does Joker Machine.
For my bike, I use 2 Super Ds (gas) with only a pull cable on each carb. I use the ART dual 1/4 turn throttle setup. So I have 2 cables on the grip, one for each carb. The PMFR setup is good too, and both are expensive.
For fuel delivery, I use an inline fuel pump from Nitrous Express and a NOS brand bypass regulator. I set the regulator around 4 psi and route the bypass back into the tank. I don't have a whole bunch of passes on this new bike, but so far so good.
I have 1 thunderjet on each carb. Don't know if they'll work with alky, I would think so, but Maura at Zipper's Performance would know for sure: 410-579-2828. If you decide to get them, make sure you get the large discharge tubes. The standard one that come with the t-jet only work up to a size 135 t-jet. That isn't big enough. Maura will know what you need.
Thanks. The part I am looking at is 11-0123. I don't see
where they offer different needle and seat options. Was this
something that S&S made Do you have a part number
It seems like this carb may have two inlets, but I don't see a good
picture of it. They refer to it as an auxillary fuel
inlet. Hard to imagine two needles and seats. Any idea of
what they are talking about
I have a Mallory 4307M bypass regulator on the bike already with a
Holley Blue pump and a single line that feeds the carb. I can
flow more than enough fuel (famous last words) than the engine burns
with the 42mm and F compressor.
The pic on page 7 of the race catalog shows a pic of the carb and 2 inlets. The main inlet is vertical at the front of the carb. The aux inlet is horizontal and on the left side of the carb. From reading the catalog, the aux inlet opens only when the throttle is open.
Originally Posted by geek
The catalog on page 8-9 shows the parts list.
That makes sense. On page 9 there is a comment "Auxiliary fuel
Originally Posted by TriRyche
inlet activated by cam on throttle shaft." I was thinking that
this was the fuel overflow fitting, which I can't seem to find.
Are all three lines then just barbed fittings It looks
like the main feed (item 24) may have an NPT fitting. Can the
auxiliary inlet hold the same pressures as the needle, or are they
expecting this to be gravity fed They talk about the valve
being controlled by an adjustable cam. Is the fuel
overflow large enought to carry all of the excess fuel once this
auxiliary valve opens If not how do you balance the flow
rates out I can just see where this valve opens and
I flood the engine.
Sorry, I don't have any experience with the turbo alky version. Have you tried call S&S tech support I have always found them to be very helpful.
The second fuel feed is controlled by a cam that operates what used to be the choke mechanism. It is an offset wheel that lifts a pin and opens a fuel delivery directly into the carby bowl without haveing to go through a needle and seat and thus getting much more fuel in. It is adjustable as to how much throttle before it starts to activate. I have found that the fuel return has trouble getting all this fuel away if the bike is not boosting and useing heaps. I run a Barry Grant 440 pump and return regulator and it delivers all the fuel you could want. I have found that when two stepping on the line if the bike does not boost strong it will flood the carby. What I have done is put a Hobbs adjustable pressure switch in the plentium and fitted a Alky fuel soleniod to that line. The line will then only flow fuel when the boost is above 10 psi (adjustable) and the motor can use the fuel comming at it. Does not run out of fuel and does not flood.
There is a glass ball needle and seat available for these. I have not needed to use one and we run upto 3 1/2 psi in fuel pressure, however they can't be a bad thing.
Thanks again!! This information is very helpful.
Phil, did you pressurize the auxillary fuel inlet
Have you looked into trying to increase the flow rate of the return
line Or, is the return (overflow) line a very small tube
Maybe you could modify the float bowl to add a high flow
return. Do you use a return pump, or just a small catch can
The Mallory regulator I am using has boost control as well.
I have never used it but did try some tests on it. From what I
remember the regulator put out some where around 2PSI with 14 PSI of
vacuum and then would increase to the regulation pressure with 14PSI of
boost. Or something like that. This may be a way to get
around the over fueling problem.
I sure would like to see one of these things before diving into
it. I stopped by a local speed shop to get a price and they
gave me the persons name to contact at S&S. I am not so
sure that they have all the answers. Those of you trying to use
this carb may know more about how to make it work. Looks
like the cost is going to be in the $600 or so range. $450 or so
for the basic carb. A lot of money if I have to spend time
modifying it to get it to work right.
Geek I can picture tape hoding your glasses together
You will most likely want to run the E flow compressor wheel and housing as it is the same size as the super D 2 1/4 and will boost like you will want it to