2 inch SUs

[Wes]

I am trying to get a pair of SUs from a jag to run on my 260 and they really dont want to. When I got them I built a linkage and put them on a 260 manifold and they ran fine except for fuel running out where the jet pump diaphram is. These were replaced but now the things just want to backfire through the carbs all the time and run best at about 30 degress btdc! They wont rev over 4000 rpm either. If nobody can help then I'll bring them to billing and maybe someone can help me then!

Cheers

Wes

(If anyone can help me then my webers can go for cheap to whoever wants them&#33<img src="http://www.zclub.net/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=''>

 

[Mr.F]

Wes - check float levels, needle seating in the piston, weight of oil in dashpot (usually use 20W-50, fill it up completely and put the plunger in - let the engine consume the excess and it will find its own level). What springs are you using with these? Do the pistons rise fully when you try to rev the engine? Do they rise too fast (too much fuel and not enough air) or do they rise too slowly (too much air and not enough fuel)? You can adjust this with different spring rates.

Obvious questions - the carbs are properly balanced aren't they? Also, is the mixture level set approximately right and the same for both carbs?

Don't even think of running huge amounts of ignition advance to overcome the problem. The Z engine will work best with about 34 degrees all in (i.e. full mechanical advance plus static timing). Static advance can be between 10 and 17 degrees depending on engine spec. and fuel used.

 

[Wes]

Everything works fine but Ive got mail back from the guy I bought them from and they were from a 3.8L C type so im guessing I should get some leaner needles! anyway thanks for the reply see you at billing

Wes