my 260z back fires really loud when i turn the motor off does any one know why??????? Thanks

With no further information that this , it sounds like you are running rich and the excess gas is detonating in the muffler. It will eventually destroy the muffler if not corrected. As well as your neighbors patience . , Gary

When I first drove my 240 home from the PO , it hardly ran after being ''tuned'' by him. One SU was set rich and the other one lean . The timing was 10 degrees retarded . I pulled into a gas station on the way home , in a not so nice part of town, and when I shut her off there was a hell of a back fire . Three guys hit the ground ! They didn't think it was vary funny . If you are running flat top carbs , my advise is to replace them with round top SUs . If you are already running SUs . They need adjustment , or maybe you have a nozzle sticking when you turn off the choke. Gary

Thanx !!!! i have a pair of round tops sitting in my other recked 260z off of a240. is the intake manifold the same or do i have to change the whole device.

I think they can be interchangable, with minor differences and adaptations you may have to make. I just put SU carbs on my 73 and used a E46 intake and E46 (or maybe E88 balance tube I can't remember) balance tube. I had the N33's as well but the E46 was cleaner and easier to polish up. I would take a look at them and use the better of the 2 or the easier swap. Others may dissagree. I am new to this and just trying to make it work, and it did. She runs after 2 years of sitting and waiting for me to get to it.

Thanx ill c how it works>

Can I have the extra set of SU's that you have.

suposedly the 260z's intake is the best of the carb'd intakes (n36 I believe) The round tops just bold right up to them. There is a guy on this site that is working on a RWHP test on the differance between the E88 intake and the N36 intake to see if there is really a differance. I don't know how far he's come with his test.

260Zlover , be sure to use the thicker insulators that go between the carb and the intake manifold . Do keep the same intake , you will need the linkage that fits between the SUs because it is of a different spacing than the flat tops. Use the air cleaner box form the 240 also . They have velocity stacks built in to them , so they are already tuned for performance at the factory . After market set ups don't have this unless you buy them separate from what I am told. Gary

thank you very much every one ill try to do the job this weekend !!!!!