I ran the SU set up on the race car for some time with no problems as far as heat soak. As you know it is very hot in Las Vegas.....45 degrees for you guys.
The only problem I ever had is with slicks on the car in long sweepers it would starve , I rotated the float 90 so that the float being shut by G forces happened under braking.

Tom

My A12GX has never had the fuel starvation problem.
It sometimes gets very hot here and when sitting in traffic the temp rises quite high.
When I stop for example at the shop to buy milk and stuff and start the car again it will fire up after half a turn and run without problem.

What might cause the problem is aftermarket extractors that are too close to the carbs. I have heard that extractors create more heat than a factory exhaust manifold.
Also, not a proper heat shield for the carbs.
My factory Hitachi SU setup has the heat shield underneath the carbs and I think this helps with preventing heat getting to the carbs.

Go with the SU's.
Nice fuel economy and nice power.
Very easy to tune and also to setup.

thanks for the advice.
I am off to the suspension place to get toe and camber specs for the Stanza strut upgrade tomorrow, so now that that the stoppers are sorted I can think about getting some more go. I'll post all that gear up and hopefully get it into the tech section so it doesnt get lost.... like so much of the info in this place.

soory better explination need

su's dont like lots of fuel presure just good flow and cool fuel so ditch mech pump and fit a small very small electric pump with a return line to the tank so you have good flow when the carbies need it and because the fuel dosnt sit at the carbies it recovers from the heat quicker

or if you have a good mech pump you can work with it too

you just need to play with a orifice return to the tank

quite like bluebird series two carbies has with its electric pump

I recommend them over the weber anyday. Easier to set up, better driveabilty (very smooth, no flatspots etc) same fuel economy and a very noticeable change in top end performance. No struggle for air/fuel at all. I dont have any heat soak issues running a heatshield. The float chamber doesnt dry up.

No matter what anyone tells you they are a great carb with plenty of power potential. Twin 1 1/2" = 38mm. Sidedraught style so straight in and well as no restrictions in the carb its self. No chokes and what not. Open the butterfly and its all straight through.

Thanks BigV-

so pumping the fuel bowl dry each time you stop is a viable option?

Quote:

Or did you just mean ditching the mechanical pump and using an eletric one instead?

for a start we just change the nedals and these are so similar to pommy su's that we just buy them instead

I run su's from time to time and yes they do have problems with heat soak but a few simle things fix it

good heat shields

and pluming a electric pump up with a return to the tank

Oh and most of the time people who are having problems is because there floats which are brass tend to get a tiny crack in them and then sink

this is easy to fix you just soak them in hot water
to get the fuel out and then resolder the crack which bubbles when under water

if you service them regular they work a treat

but dont expect your average mechanic to want to work on them

Did you have any problems finding a decent range of jets for the Hitachi's? That was the other comment was that jets were 'impossible' to find.

With the general disregard people over here have for anything over 10 years old-
"hi, I've got a dat-"
"sorry mate cant help you"-click
I wouldn't be surprised if he gave up looking fairly quickly.

I've had Hitachi SUs on an L16 and L20, and I've had genuine SUs on and A12 and A14.

They are prone to heat soak with the exposed fuel bowls over the exhaust on these non-crossflow engines. But a decent heat shield and insulating wrap over the fuel bowls has always done the trick for me.

The problem is not that it floods the engine, but the heat evapourates the fuel in the bowls.

Don't be put off by him. SU's are a good carb for street engines and this problem is easily overcome.

Nissan have used twin hitachis on must of there early datsun models for propably close to 20+ years. If they were no good Im sure they would dropped them for something else quick smart. I personally ran some on my coupe for about 5 years, with minimal tuning problems. Just reguarly check the oil level in the carb tops. They were excellent on fuel an made decent power. The weber is equally as qualified to do the job, provided its jetted suitably. I think the twins are the more sporty option IMO.

Benny